Chapter XII: Hominoxious Arthropods (1)

The following synoptic tables are presented in the hope that they may be of service in giving the reader a perspective of the relationships of the Arthropoda in general and enabling him to identify the more important species which have been found noxious to man. Though applicable chiefly to the arthropods found in the United States, exotic genera and species which are concerned in the transmission of disease are also included. For this reason the keys to the genera of the Muscids of the world are given. As will be seen, the tables embrace a number of groups of species which are not injurious. This was found necessary in order that the student might not be lead to an erroneous determination which would result were he to attempt to identify a species which heretofore had not been considered noxious, by means of a key containing only the noxious forms. The names printed in BOLD FACED TYPE indicate the hominoxious arthropods which have been most commonly mentioned in literature.

CRUSTACEA

Arthropods having two pairs of antennae which are sometimes modified for grasping, and usually with more than five pairs of legs. With but few exceptions they are aquatic creatures. Representatives are: Crabs, lobsters, shrimps, crayfish, water-fleas, and woodlice. To this class belongs the CYCLOPS (fig. 122) a genus of minute aquatic crustaceans of which at least one species harbors _Dracunculus medinensis_, the Guinea worm (fig. 121).

MYRIAPODA

Elongate, usually vermiform, wingless, terrestrial creatures having one pair of antennae, legs attached to each of the many intermediate body segments. This group is divided into two sections, now usually given class rank: the DIPLOPODA or millipedes (fig. 13), commonly known as thousand legs, characterized by having two pairs of legs attached to each intermediate body segment, and the CHILOPODA or centipedes (fig. 14) having only one pair of legs to each body segment.

ARACHNIDA

In this class the antennae are apparently wanting, wings are never present, and the adults are usually provided with four pairs of legs. Scorpions, harvest-men, spiders, mites, etc.

HEXAPODA (Insects)

True insects have a single pair of antennae, which is rarely vestigial, and usually one or two pairs of wings in the adult stage. Familiar examples are cockroaches, crickets, grasshoppers, bugs, dragon-flies, butterflies, moths, mosquitoes, flies, beetles, ants, bees and wasps.

ORDERS OF THE ARACHNIDA

a. Abdomen distinctly segmented. A group of orders including scorpions,
(fig. 11), whip-scorpions (fig. 10), pseudo-scorpions, solpugids
(fig. 12) harvest-men (daddy-long-legs or harvestmen), etc.
ARTHROGASTRA

aa. Abdomen unsegmented, though sometimes with numerous annulations
SPHAEROGASTRA

b. A constriction between cephalothorax and abdomen (fig. 7). True
Spiders ARANEIDA

bb. No deep constriction between these parts.

c. Legs usually well developed, body more or less depressed (fig.
49). Mites ACARINA

cc. Legs stumpy or absent, body more or less elongate or vermiform,
or if shorter, the species is aquatic or semi-aquatic in habit.

d. Four pairs of short legs; species inhabiting moss or water.
Water-bears. TARDIGRADA

dd. Two pairs of clasping organs near the mouth, instead of legs,
in the adult; worm-like creatures parasitic within the nasal
passages, lungs, etc. of mammals and reptiles (fig. 148).
Tongue worms. LINGUATULINA

ACARINA[E]

a. Abdomen annulate, elongate; very minute forms, often with but four
legs (fig. 62). DEMODICOIDEA

b. With but four legs of five segments each. Living on plants, often
forming galls. ERIOPHYIDAE

bb. With eight legs, of three segments each. Living in the skin of
mammals. DEMODICIDAE

To this family belongs the genus DEMODEX found in the sebaceous
glands and hair follicles of various mammals, including man. _D.
phylloides_ Csokor has been found in Canada on swine, causing
white tubercles on the skin. _D. bovis_ Stiles has been reported
from the United States on cattle, upon the skin of which they
form swellings. D. FOLLICULORUM Simon is the species found on
man. See page 78.

aa. Abdomen not annulate nor prolonged behind; eight legs in the adult
stage.

b. With a distinct spiracle upon a stigmal plate on each side of the
body (usually ventral) above the third or fourth coxae or a little
behind (fig. 50); palpi free; skin often coriaceous or leathery;
tarsi often with a sucker.

c. Hypostome large (fig. 50), furnished below with many recurved
teeth; venter with furrows, skin leathery; large forms, usually
parasitic. IXODOIDEA

d. Without scutum but covered by a more or less uniform leathery
integument; festoons absent; coxae unarmed, tarsi without
ventral spurs; pulvilli absent or vestigial in the adults;
palpi cylindrical; sexual dimorphism slight. ARGASIDAE

e. Body flattened, oval or rounded, with a distinct flattened
margin differing in structure from the general integument;
this margin gives the body a sharp edge which is not
entirely obliterated even when the tick is full fed.
Capitulum (in adults and nymphs) entirely invisible
dorsally, distant in the adult by about its own length from
the anterior border. Eyes absent. ARGUS Latr.

f. Body oblong; margin with quadrangular cells; anterior tibiae
and metatarsi each about three times as long as broad. On
poultry, southwest United States. A. PERSICUS MINIATUS

_A. brevipes_ Banks, a species with proportionately shorter
legs has been recorded from Arizona.

ff. With another combination of characters. About six other
species of _Argas_ from various parts of the world,
parasitic on birds and mammals.

ee. Body flattened when unfed, but usually becoming very convex
on distention; anterior end more or less pointed and
hoodlike; margin thick and not clearly defined, similar in
structure to the rest of the integument and generally
disappearing on distention; capitulum subterminal, its
anterior portions often visible dorsally in the adult; eyes
present in some species.

f. Integument pitted, without rounded tubercles; body provided
with many short stiff bristles; eyes absent. On horses,
cattle and man (fig. 48). OTIOBIUS Banks.

O. MEGNINI, a widely distributed species, is the type of
this genus.

ff. Integument with rounded tubercles or granules; body
without stiff bristles. ORNITHODOROS Koch.

g. Two pairs of eyes; tarsi IV with a prominent subterminal
spur above; leg I strongly roughened. On cattle and man.
O. CORIACEUS

gg. No eyes; no such spur on the hind tarsi.

h. Tarsi I without humps above. _O. talaje._

hh. Tarsi I with humps above.

i. Tarsi IV without distinct humps above. On hogs,
cattle and man. O. TURICATA

ii. Tarsi IV with humps nearly equidistant (fig. 142).
Africa. O. MOUBATA

dd. With scutum or shield (fig. 50); festoons usually present;
coxae usually armed with spurs, tarsi generally with one or two
ventral spurs; pulvilli present in the adults; sexual
dimorphism pronounced. IXODIDAE

e. With anal grooves surrounding anus in front; inornate;
without eyes; no posterior marginal festoons; venter of the
male with non-salient plates. Numerous species, 14 from the
United States, among them I. RICINUS (fig. 49 and 50),
SCAPULARIS, COOKEI, _hexagonus_, _bicornis_. IXODES Latr.
(including Ceratixodes).

ee. With anal groove contouring anus behind, or groove faint or
obsolete.

f. With short palpi (fig. 149).

g. Without eyes, inornate, with posterior marginal festoons;
male without ventral plates. Numerous species. _H.
chordeilis_ and _leporis-palustris_ from the United
States. _Haemaphysalis_ Koch.

gg. With eyes.

h. Anal groove distinct; posterior marginal festoons
present.

i. Base of the capitulum (fig. 150c) rectangular
dorsally; usually ornate. DERMACENTOR Koch.

j. Adults with four longitudinal rows of large
denticles on each half of hypostome; stigmal plate
nearly circular, without dorso-lateral
prolongation, goblets very large, attaining 43u to
115u in diameter; not over 40 per plate, each
plate surrounded by an elevated row of regularly
arranged supporting cells; white rust wanting;
base of capitulum distinctly broader than long,
its postero-lateral angles prolonged slightly, if
at all; coxae T with short spurs; trochanter I with
small dorso-terminal blade. Texas, Arizona, etc.
_D. nitens_

jj. Adults with three longitudinal rows of large
denticles on each half of hypostome; goblet cells
always more than 40 per plate; whitish rust
usually present.

k. Dorso-lateral prolongation of stigmal plate small
or absent; plates of the adults distinctly
longer than broad; goblet cells large, usually
30u to 85u in diameter, appearing as very coarse
punctations on untreated specimens, but on
specimens treated with caustic potash they
appear very distinct in outline; base of
capitulum distinctly (usually about twice)
broader than long, the postero-lateral angles
distinctly produced caudad; spurs of coxae I
long, lateral spur slightly longer than median;
trochanter I with dorso-terminal spur. _D.
albipictus_, (= _variegatus_), _salmoni_,
_nigrolineatus_.

kk. Dorso-lateral prolongation of stigmal plate
distinct.

l. Body of plate distinctly longer than broad;
goblet cells of medium size, usually 17.5u to
35u or 40u in diameter, appearing as medium
sized punctuations on untreated specimens, but
on the specimens treated with caustic potash
they appear very distinct in outline, which is
not circular; base of capitulum usually less
than twice as broad as long, the
postero-lateral angles always distinctly
prolonged caudad.

m. Trochanter I with distinct dorso-subterminal
retrograde sharp, digitate spur;
postero-lateral angles of capitulum
pronouncedly prolonged caudal, 112u to 160u
long; goblet cells attain 13u to 40u in
diameter; type locality California. D.
OCCIDENTALIS

mm. Trochanter I with dorso-terminal blade;
postero-lateral angles of capitulum with
rather short prolongations.

n. Stigmal plate small, goblet cells not
exceeding 45 in the male or 100 in the
female; scutum with little rust, coxa I
with short spurs, the inner distinctly
shorter than the outer. _D.
parumapertus-marginatus_

nn. Stigmal plate larger; goblet cells over 70
in the male and over 100 in the female;
coxa I with longer spurs, inner slightly
shorter than the outer; scutum with
considerable rust. D. VENUSTUS[F]

ll. Goblet cells small, rarely exceeding 17.6u,
occasionally reaching 19u in diameter; on
untreated specimens they appear as very fine
granulations, and on specimens treated with
caustic potash they may be difficult to see,
but their large number can be determined from
the prominent stems of the goblets; surface of
outline of the goblets distinctly circular;
base of the capitulum usually less than twice
as broad as long, the postero-lateral angle
distinctly prolonged caudad; spurs of coxae I
long. _D. reticulatus_ and _electus_ (=
_variabilis_?)

ii. Base of the capitulum (fig. 151) usually hexagonal
(except in the male of _puchellus_); and usually
inornate.

j. No ventral plate or shield in either sex (fig.
153). R. BICORNIS from the United States.
RHIPICENTOR Nuttall

jj. Males with a pair of adanal shields, and usually a
pair of accessory adanal shields. Numerous
species, among them _R. sanguineus_ (fig. 154) and
_texanus_, the latter from the United States.
_Rhipicephalus_ Koch

hh. Anal grooves faint or obsolete; no marginal festoons.

i. Short palpi; highly chitinized; unfed adults of large
size; coxae conical; male with a median plate
prolonged in two long spines projecting caudad;
segments of leg pair IV greatly swollen (fig. 155,
156). _M. winthemi_ _Margaropus_ Karsch

ii. Very short palpi, ridged dorsally and laterally;
slightly chitinized; unfed adults of smaller size;
coxae I bifid; male with adanal and accessory adanal
shields (fig. 139). B. ANNULATUS. BOOPHILUS Curtis

ff. Palpi longer than broad (fig. 157).

g. Male with pair of adanal shields, and two posterior
abdominal protrusions capped by chitinized points;
festoons present or absent. Several species, among them
H. AEGYPTICUM (fig. 140) from the old world. HYALOMMA
Koch

gg. Male without adanal shields but small ventral plaques
are occasionally present close to the festoons. Many
species, a few from the United States (fig. 157).
AMBLYOMMA Koch

h. Coxa I with but one spine; metatarsi (except I) with
two thickened spurs at tips. _A. maculatum_

hh. Coxa I with two spines; metatarsi without stout spurs
at tips, only slender hairs.

i. Projections of coxa I blunt and short. Large species
on the gopher tortoise in Florida. _A. tuberculatum_

ii. Projections of coxa I longer, and at least one of
them sharp pointed; second segment of palpus twice
as long as the third; coxa IV of the male with a
long spine.

j. Porose areas nearly circular; shield of both sexes
pale yellowish, with some silvery streaks and
marks, and some reddish spots; shield of female as
broad as long. A. CAJENNENSE (= MIXTUM).

jj. Porose areas elongate, shield brown, in the female
with an apical silvery mark, in the male with two
small and two or four other silvery spots; shield
of the female longer than broad (fig 158 e). A.
AMERICANUM.

cc. Hypostome small, without teeth, venter without furrows; body
often with coriaceous shields, posterior margin of the body
never crenulate (i.e. without festoons); no eyes. GAMASOIDEA.

d. Parasitic on vertebrates; mandibles fitted for piercing; body
sometimes constricted. DERMANYSSIDAE.

e. Anal plate present. DERMANYSSINAE.

f. Body short; legs stout, hind pair reaching much beyond the
tip of the body. On bats. _Pteroptus_ Dufour.

ff. Body long; hind legs not reaching beyond the tip of the
body.

g. Peritreme on the dorsum, very short; body distinctly
constricted. _Ptilonyssus_ Berl.

gg. Peritreme on the venter, longer; body not distinctly
constricted.

h. Mandibles in both sexes chelate. Parasitic on bats,
mice and birds (fig. 150, h). LIPONYSSUS Kol.

The species L. (= LEIOGNATHUS) SYLVIARUM frequents the
nests of warblers. An instance is on record of
these mites attacking man, causing a pruritis.

hh. Mandibles in the male chelate (fig. 158 j), in the
female long, styliform. Parasitic on birds.
DERMANYSSUS Dug. Two species of importance may be
noted, _D. hirundinus_ and D. GALLINAE. The latter
(fig. 51) is a serious pest of poultry, sometimes
attacking man, causing itching and soreness.

ee. Anal plate absent. In lungs and air passages of some
mammals. HALARACHNINAE.

dd. Free or attached to insects, rarely on vertebrates.

e. First pair of legs inserted within the same body opening as
the oral tube; genital apertures surrounded by the sternum.
On insects. UROPODIDAE.

ee. First pair of legs inserted at one side of the mouth
opening; male genital aperture usually on the anterior
margin of the sternal plate. GAMASIDAE.

This family contains a number of genera, some of which are
found upon mammals, though the majority affect only other
arthropods. One species, LAELAPS STABULARIS, frequents the
bedding in stables, and in one instance at least, has
occasioned irritation and itching, in man.

bb. No distinct spiracle in the stigmal plate on each side of the
body.

c. Body usually coriaceous, with few hairs, with a specialized seta
arising from a pore near each posterior corner of the
cephalothorax; no eyes; mouth parts and palpi very small;
ventral openings of the abdomen large; tarsi without sucker. Not
parasitic. ORIBATOIDEA.

cc. Body softer; without such specialized seta.

d. Aquatic species. HYDRACHNOIDEA.

dd. Not aquatic.

e. Palpi small, three segmented, adhering for some distance to
the lip; ventral suckers at genital opening or near anal
opening usually present; no eyes; tarsi often end in
suckers; beneath the skin on the venter are seen rod-like
epimera that support the legs; body often entire. Adults
frequently parasitic. SARCOPTOIDEA.

f. With tracheae; no ventral suckers; legs ending in claws;
body divided into cephalothorax and abdomen; the female
with a clavate hair between legs I and II. Usually not
parasitic on birds and mammals. TARSONEMIDAE

g. Hind legs of female ending in claw and sucker as in the
other pairs. PEDICULOIDINAE

To this sub-family belongs the genus PEDICULOIDES

P. ventricosus is described on page 69.

gg. Hind legs of the female end in long hairs. TARSONEMINAE

TARSONEMUS INTECTUS Karpelles, normally found upon grain,
is said to attack man in Hungary and Russia. Other
species of the genus affect various plants (c.f. fig.
150, g).

ff. Without tracheae; no such clavate hair.

g. Genital suckers usually present; integument usually
without fine parallel lines.

h. Legs short, without clavate hair on tarsi I and II. On
insects. CANESTRINIDAE.

hh. Legs longer, with a clavate hair on tarsi I and II.
Not normally parasitic except on bees. TYROGLYPHIDAE

i. Dorsal integument more or less granulate; claws very
weak, almost invisible; some hairs of the body
plainly feathered; ventral apertures large.
GLYCIPHAGUS Her.

This genus occurs in the United States. In Europe the
mites have been found feeding on all sorts of
substances. They are known as sugar mites and
cause the disease known as grocer's itch. G.
DOMESTICUS and G. PRUNORUM are old world species
(fig. 150, d).

ii. Dorsal integument not granulate; claws distinct; no
prominent feathered hairs; ventral aperture small.

j. Mandibles not chelate; elongate, and toothed below;
body without long hairs; palpi enlarged at tip and
provided with two divergent bristles. Species feed
on decaying substances. _Histiostoma_ Kram.

jj. Mandibles chelate; palpi not enlarged at the tip,
nor with two bristles.

k. No clavate hair on the base of tarsi I and II; no
suture between cephalothorax and abdomen. Live
on bees or in their nests. _Trichotarsus_ Can.

kk. A clavate or thickened hair at the base of tarsi
I and II.

l. The bristle on the penultimate segment of the
legs arises from near the middle; no suture
between the cephalothorax and abdomen. The
species, some of which occur in the United
States, feed on dried fruit, etc.
_Carpoglyphus_ Robin.

ll. The bristle on the penultimate segment of the
legs arise from near the tip; a suture between
cephalothorax and abdomen.

m. Cephalothorax with four distinct and long
bristles in a transverse row; tarsi I and II
about twice as long as the preceding segment
(fig. 150 f). TYROGLYPHUS Latr.

n. Some bristles on tarsi I and II near
middle, distinctly spine-like; the sense
hair about its length from the base of the
segment. Several species in the United
States belong to this group.

nn. No spine-like bristles near the middle of
the tarsi; sense hair not its length from
the base of the segment.

o. Of the terminal abdominal bristles, only
two are about as long as the abdomen;
leg I of the male greatly thickened and
with a spine at apex of the femur below.
T. FARINAE.

oo. Of the terminal abdominal bristles at
least six or more are very long, nearly
as long as the body.

p. Bristles of the body distinctly plumose
or pectinate; tarsi very long. T.
LONGIOR.

pp. Bristles of the body not pectinate.

q. In mills, stored foods, grains, etc.
Third and fourth joints of hind legs
scarcely twice as long as broad;
abdominal bristles not unusually
long; legs I and II of the male not
unusually stout. T. AMERICANUS.

qq. With other characters and habits.
_T. lintneri_ (fig. 150 f) the
mushroom mite, and several other
species.

mm. Cephalothorax with but two long distinct
bristles (besides the frontal pair), but
sometimes a very minute intermediate pair;
tarsi I and II unusually short and not twice
as long as the preceding segment.

n. Tarsi with some stout spines. RHIZOGLYPHUS
Clap.

The species of this genus are vegetable
feeders. Several occur in the United
States. R. PARASITICUS and R.
SPINITARSUS have been recorded from the
old world, attacking human beings who
handle affected plants.

nn. Tarsi with only fine hairs. MONIEZIELLA
Berl.

The species of this genus, as far as known,
are predaceous or feed on recently
killed animal matter. Several species
occur in the United States. M. (=
HISTIOGASTER) ENTOMOPHAGA (fig. 152)
from the old world has been recorded as
injurious to man.

gg. Genital suckers absent; integument with fine parallel
lines. Parasitic on birds and mammals.

h. Possessing a specially developed apparatus for clinging
to hairs of mammals. LISTROPHORIDAE.

hh. Without such apparatus.

i. Living on the plumage of birds. ANALGESIDAE.

ii. In the living tissues of birds and mammals.

j. Vulva longitudinal. In the skin and cellular
tissues of birds. CYTOLEICHIDAE.

This family contains two species, both occurring in
the United States on the common fowl.
_Laminosioptes cysticola_ occurs on the skin and
also bores into the subcutaneous tissue where it
gives rise to a calcareous cyst. _Cytoleichus
nudus_ is most commonly found in the air
passages and air cells.

jj. Vulva transverse. In the skin of mammals and
birds. SARCOPTIDAE

k. Anal opening on the dorsum.

l. Third pair of legs in the male without apical
suckers. On cats and rabbits. NOTOEDRES
Rail.

The itch mite of the cat, N. CATI (fig. 61) has
been recorded on man.

ll. Third leg in the male with suckers. On bats
_Prosopodectes_ Can.

kk. Anal opening below.

l. Pedicel of the suckers jointed; mandibles
styliform and serrate near the tip. PSOROPTES
Gerv. P. COMMUNIS OVIS is the cause of sheep
scab.

ll. Pedicel of the suckers not jointed; mandibles
chelate.

m. No suckers on the legs of the females;
parasitic on birds, including chickens. _C.
mutans_ is itch mite of chickens.
_Cnemidocoptes_ Furst.

mm. Suckers at least on legs I and II; parasitic
on mammals.

n. Legs very short; in the male the hind pairs
equal in size; body usually short.
SARCOPTES Latr.

S. SCABIEI is the itch mite of man (fig.
56).

nn. Legs more slender; in the male the third
pair is much larger than the fourth; body
more elongate.

o. Female with suckers on the fourth pair of
legs. Species do not burrow in the skin,
but produce a scab similar to sheep
scab. They occur in the ox, horse, sheep
and goat. CHORIOPTES Gerv. C. SYMBIOTES
BOVIS of the ox has been recorded a few
times on man.

oo. Female without suckers to the fourth
legs.

p. Hind part of the male abdomen with two
lobes. On a few wild animals.
_Caparinia_ Can.

pp. Hind part of the male abdomen without
lobes. Live in ears of dogs and cats.
_Otodectes_ Canestr.

_O. cynotis_ Hering (fig. 150 e) has
been taken in the United States.

ee. Palpi usually of four or five segments, free; rarely with
ventral suckers near genital or anal openings; eyes often
present; tarsi never end in suckers; body usually divided
into cephalothorax and abdomen; rod-like epimera rarely
visible; adults rarely parasitic.

f. Last segment of the palpi never forms a thumb to the
preceding segment; palpi simple, or rarely formed to hold
prey; body with but few hairs. EUPODOIDEA.

g. Palpi often geniculate, or else fitted for grasping prey;
mandibles large and snout like; cephalothorax with four
long bristles above, two in front, two behind; last
segment of leg I longer than the preceding segment,
often twice as long. BDELLIDAE.

gg. Palpi never geniculate (fig. 158a), nor fitted for
grasping prey: beak small; cephalothorax with bristles
in different arrangement; last segment of leg I shorter
or but little longer than the preceding joint; eyes when
present near posterior border. EUPODIDAE

Moniez has described a species from Belgium (TYDEUS
MOLESTUS) which attacks man. It is rose colored;
eyeless; its legs are scarcely as long as its body,
the hind femur is not thickened; the mandibles are
small and the anal opening is on the venter. The
female attains a length of about 0.3 mm.

ff. Last segment of the palpus forms a thumb to the preceding,
which ends in a claw (with few exceptions); body often
with many hairs (fig. 158 k). TROMBIDOIDEA.

g. Legs I and II with processes bearing spines; skin with
several shields; coxae contiguous. CAECULIDAE.

gg. Legs I and II without such processes; few if any
shields.

h. Palpi much thickened on the base, moving laterally,
last joint often with two pectinate bristles; no eyes;
legs I ending in several long hairs; adult sometimes
parasitic. CHEYLETIDAE

CHEYLETUS ERUDITUS, which frequents old books, has once
been found in pus discharged from the ear of man.

hh. Palpi less thickened, moving vertically; eyes usually
present; leg I not ending in long hairs.

i. Coxae contiguous, radiate; legs slender, bristly; body
with few hairs; no dorsal groove; tarsi not swollen.
ERYTHRAEIDAE.

ii. Coxae more or less in two groups; legs less bristly.

j. Body with fewer, longer hairs; often spinning
threads; no dorsal groove; tarsi never swollen;
mandibles styliform (for piercing). TETRANYCHIDAE

The genus TETRANYCHUS may be distinguished from the
other genera occurring in the United States by
the following characters: No scale-like
projections on the front of the cephalothorax;
legs I as long or longer than the body; palp
ends in a distinct thumb; the body is about 1.5
times as long as broad. T. MOLESTISSIMUS Weyenb.
from South America, and T. TELARIUS from Europe
and America ordinarily infesting plants, are
said also to molest man.

jj. Body with many fine hairs or short spines; not
spinning threads; often with dorsal groove; tarsi
often swollen.

k. Mandibles styliform for piercing. RHYCHOLOPHIDAE.

kk. Mandibles chelate, for biting. TROMBIDIDAE

The genus TROMBIDIUM has recently been subdivided
by Berlese into a number of smaller ones, of
which some five or six occur in the United
States. The mature mite is not parasitic but
the larvae which are very numerous in certain
localities will cause intense itching,
soreness, and even more serious complications.
They burrow beneath the skin and produce
inflamed spots. They have received the popular
name of "RED BUG." The names LEPTUS AMERICANUS
and L. IRRITANS have been applied to them,
although they are now known to be immature
stages. (Fig. 44.)

HEXAPODA (Insecta)

The Thysanura (springtails and bristletails), the Neuropteroids (may-flies, stone-flies, dragon-flies, caddis-flies, etc.), Mallophaga (bird lice), Physopoda (thrips), Orthoptera (grasshoppers, crickets, roaches), are of no special interest from our viewpoint. The remaining orders are briefly characterized below.

SIPHUNCULATA (page 275)

Mouth parts suctorial; beak fleshy, not jointed; insect wingless; parasitic upon mammals. Metamorphosis incomplete. Lice.

HEMIPTERA (page 275)

Mouth parts suctorial; beak or the sheath of the beak jointed; in the mature state usually with four wings. In external appearance the immature insect resembles the adult except that the immature form (i.e. nymph) never has wings, the successive instars during the process of growth, therefore, are quite similar; and the metamorphosis is thus incomplete. To this order belong the true bugs, the plant lice, leaf hoppers, frog hoppers, cicadas, etc.

LEPIDOPTERA

The adult insect has the body covered with scales and (with the rare exception of the females of a few species) with four wings also covered with scales. Proboscis, when present, coiled, not segmented, adapted for sucking. Metamorphosis complete, i.e. the young which hatches from the egg is quite unlike the adult, and after undergoing several molts transforms into a quiescent pupa which is frequently enclosed in a cocoon from which the adult later emerges. The larvae are known as caterpillars. Butterflies and moths.

DIPTERA (page 285)

The adult insect is provided with two, usually transparent, wings, the second pair of wings of other insects being replaced by a pair of halteres or balancers. In a few rare species the wings, or halteres, or both, are wanting. The mouth parts, which are not segmented, are adapted for sucking. The tarsi are five-segmented. Metamorphosis complete. The larvae, which are never provided with jointed legs, are variously known as maggots, or grubs, or wrigglers. Flies, midges, mosquitoes.

SIPHONAPTERA (page 316)

Mouth parts adapted for sucking; body naked or with bristles and spines; prothorax well developed; body compressed; tarsi with five segments; wings absent. Metamorphosis complete. The larva is a wormlike creature. Fleas.

COLEOPTERA

Adult with four wings (rarely wanting), the first pair horny or leathery, veinless, forming wing covers which meet in a line along the middle of the back. Mouth parts of both immature stages and adults adapted for biting and chewing. Metamorphosis complete. The larvae of many species are known as grubs. Beetles.

HYMENOPTERA

Adult insect with four, usually transparent, wings, wanting in some species. Mouth parts adapted for biting and sucking; palpi small; tarsi four or five-segmented. Metamorphosis complete. Parasitic four-winged flies, ants, bees, and wasps.

SIPHUNCULATA AND HEMIPTERA

a. Legs with claws fitted for clinging to hairs; wings wanting;
spiracles of the abdomen on the dorsal surface. (= ANOPLURA =
PARASITICA) SIPHUNCULATA.

b. Legs not modified into clinging hooks; tibia and tarsus very long
and slender; tibia without thumb-like process; antennae
five-segmented. HAEMATOMYZIDAE Endr.

_Haematomyzus elephantis_ on the elephant.

bb. Legs modified into clinging hooks; tibia and tarsus usually short
and stout; tibia with a thumb-like process; head not anteriorly
prolonged, tube-like.

c. Body depressed; a pair of stigmata on the mesothorax, and
abdominal segments three to eight; antennae three to
five-segmented.

d. Eyes large, projecting, distinctly pigmented; pharynx short and
broad; fulturae (inner skeleton of head) very strong and broad,
with broad arms; proboscis short, scarcely attaining the
thorax. PEDICULIDAE

e. Antennae three-segmented. A few species occurring upon old
world monkeys. _Pedicinis_ Gerv.

ee. Antennae five-segmented.

f. All legs stout; thumb-like process of the tibia very long
and slender, beset with strong spines, fore legs stouter
than the others; abdomen elongate, segments without
lateral processes; the divided telson with a conical
process posteriorly upon the ventral side. PEDICULUS L.

g. Upon man.

h. Each abdominal segment dorsally with from one to three
more or less regular transverse rows of small setae;
antenna about as long as the width of the head. Head
louse (fig. 65). P. HUMANUS.

hh. "No transverse rows of abdominal setae; antenna longer
than the width of the head; species larger." Piaget.
Body louse of man. P. CORPORIS.

gg. Upon apes and other mammals. _P. pusitatus_ (?).

ff. Fore legs delicate, with very long and slender claws;
other legs very stout with short and stout claws;
thumb-like process of the tibia short and stout; abdomen
very short and broad; segment one to five closely crowded,
thus the stigmata of segments three to five apparently
lying in one segment; segments five to eight with lateral
processes; telson without lateral conical appendages (fig.
69). Crab louse of man. PHTHIRUS PUBIS.

dd. Eyes indistinct or wanting; pharynx long and slender, fulturae
very slender and closely applied to the pharynx; proboscis
very long. Several genera found upon various mammals.
HAEMATOPINIDAE.

cc. Body swollen; meso- and metathorax, and abdominal segments two
to eight each with a pair of stigmata; eyes wanting; antennae
four or five-segmented; body covered with stout spines. Three
genera found upon marine mammals. ECHINOPHTHIRIIDAE

aa. Legs fitted for walking or jumping; spiracles of abdomen usually
ventral; beak segmented.

b. Apex of head usually directed anteriorly; beak arising from its
apex; sides of the face remote from the front coxae; first pair of
wings when present thickened at base, with thinner margins.
HETEROPTERA

c. Front tarsi of one segment, spade-form (palaeformes); beak short,
at most two-segmented; intermediate legs long, slender;
posterior pair adapted for swimming. CORIXIDAE

cc. Front tarsi rarely one-segmented, never spade-form; beak free,
at least three-segmented.

d. Pulvilli wanting.

e. Hemelytra usually with a distinct clavus (fig. 159), clavus
always ends behind the apex of the scutellum, forming the
commissure. (Species having the wings much reduced or
wanting should be sought for in both sections.)

f. Antennae very short; meso- and metasternum composite; eyes
always present.

g. Ocelli present; beak four-segmented. OCHTERIDAE and
NERTHRIDAE.

gg. Ocelli wanting; antennae more or less hidden in a groove.

h. Anterior coxae inserted at or near anterior margin of
the prosternum; front legs raptorial; beak
three-segmented BELOSTOMIDAE (with swimming legs),
NEPIDAE, NAUCORIDAE.

i. Metasternum without a median longitudinal keel;
antennae always four-segmented.

j. Beak short, robust, conical; the hairy fleck on the
corium elongate, large, lying in the middle
between the inner angle of the membrane and the
outer vein parallel to the membrane margin;
membrane margin S-shaped.

k. The thick fore femur with a relatively deep
longitudinal furrow to receive the tibia.
Several American species (fig. 19f.). BELOSTOMA
(= Lethocerus Mayer)

kk. The less thickened fore femur without such a
furrow. B. GRISEUS. BENACUS Stal.

jj. Beak slender, cylindrical; the hairy spot on the
corium rounded lying next to the inner angle of
the membrane.

k. Membrane large, furrow of the embolium broadened.
_Z. aurantiacum_, _fluminea_, etc. _Zaitha_

kk. Membrane very short; furrow of embolium not
broadened. Western genus. _Pedinocoris_

ii. Metasternum with a long median longitudinal keel.
Southwestern forms. _Abedus ovatus_ and _Deniostoma
dilatato_

hh. Anterior coxae inserted at the posterior margin of the
prosternum; legs natatorial. Back swimmers (fig. 19 b.).
NOTONECTIDAE

i. Apices of the hemelytra entire; the three pairs of legs
similar in shape; beak three-segmented; abdomen not
keeled or hairy. _Plea_ Leach

ii. Apices of hemelytra notched; legs dissimilar; beak
four-segmented; abdomen keeled and hairy.

j. Hemelytra usually much longer than the abdomen;
fourth segment of the antenna longer than the third
segment; hind tarsi with claws. _Bueno_ Kirk.

jj. Hemelytra but little longer than the abdomen; fourth
segment of the antenna shorter than the third
segment; hind tarsi without claws (fig. 19b).
NOTONECTA L.

ff. Antennae longer than the head; or if shorter, then the eyes
and ocelli absent.

g. Eyes, ocelli, and scutellum wanting; beak
three-segmented; head short; hemelytra always short;
membrane wanting. Insects parasitic on bats. POLYCTENIDAE

gg. Eyes present.

h. First two antennal segments very short, last two long,
pilose, third thickened at the base; ocelli present,
veins of the hemelytra forming cells. DIPSOCORIDAE (=
CERATOCOMBIDAE) including SCHIZOPTERIDAE.

hh. Third segment of the antenna not thickened at the
base, second as long or longer than the third, rarely
shorter.

i. Posterior coxae hinged (cardinate), if rarely
rotating, the cuneus is severed, the membrane is one
or two-celled, and the meso- and metasternum are
composite.

j. Ocelli absent, clypeus dilated toward the apex;
hemelytra always short, membrane wanting. Species
parasitic. Bed bugs, etc. CIMICIDAE

k. Beak short, reaching to about the anterior coxae;
scutellum acuminate at the apex; lateral margin
of the elytra but little reflexed, apical margin
more or less rounded; intermediate and posterior
coxae very remote.

l. Body covered with short hairs, only the sides
of the pronotum and the hemelytra fringed with
longer hairs; antennae with the third and
fourth segments very much more slender than
the first and second; pronotum with the
anterior margin very _deeply sinuate_. CIMEX
L.

m. Sides of the pronotum widely dilated, broader
than the breadth of one eye, and densely
fringed with backward curved hairs; apical
margin of the hemelytra nearly straight,
rounded toward the interior or exterior
angles.

n. Body covered with very short hairs; second
segment of the antenna shorter than the
third; sides of the pronotum feebly
reflexed, fringed with shorter hairs than
the breadth of one eye; hemelytra with the
commissural (inner) margin rounded and
shorter than the scutellum, apical margin
rounded towards the interior angle. The
common bed bug (fig. 19h). C. LECTULARIUS
Linn

nn. Body covered with longer hairs; second and
third segments of the antenna of equal
length; side of the pronotum narrowly, but
distinctly, reflexed, fringed with longer
hairs than the breadth of one eye;
hemelytra with the commissural margin
straight and longer than the scutellum,
apical margin rounded towards the exterior
angle. Species found on bats in various
parts of the United States. _C.
pillosellus_ Hov.

mm. Sides of the pronotum neither dilated, nor
reflexed, fringed with less dense and nearly
straight hairs; hemelytra with the apical
margin distinctly rounded. Parasitic on man,
birds and bats. Occurs in the old world,
Brazil and the West Indies. C. HEMIPTERUS
Fabr. (= rotundatus)

ll. Body clothed with rather longer silky hairs;
third and fourth segments of the antenna
somewhat more slender than the first and
second; anterior margin of the pronotum _very
slightly sinuate_ or nearly straight in the
middle, produced at the lateral angles. This
is the species which in American collections
is known as _C. hirundinis_, the latter being
an old world form. It is found in swallows
nests. O. VICARIUS. OECIACUS Stal

kk. Beak long, reaching to the posterior coxae;
scutellum rounded at the apex; lateral margins
of the elytra strongly reflexed, apical margin
slightly sinuate toward the middle; intermediate
and posterior coxae sub-contiguous. This species
infests poultry in southwest United States and
in Mexico. H. INODORUS. HAEMATOSIPHON Champ.

jj. Ocelli present, if rarely absent in the female,
then the tarsus has two segments; or if with three
tarsal segments, the wing membrane with one or two
cells.

k. Beak four-segmented, or with two-segmented tarsi.
ISOMETOPIDAE, MICROPHYSIDAE, and some
CAPSIDAE.

kk. Beak three-segmented.

l. Hemelytra with embolium; head horizontal, more
or less conical; membrane with one to four
veins, rarely wanting. ANTHOCORIDAE

Several species of this family affecting man
have been noted, ANTHOCORIS KINGI and
CONGOLENSE, from Africa and LYCTOCORIS
CAMPESTRIS from various parts of the world.
LYCTOCORIS FITCHII Reuter (fig. 19 j), later
considered by Reuter as a variety of L.
CAMPESTRIS, occurs in the United States.

ll. Hemelytra without embolium. Superfamily
ACANTHIOIDEA (= SALDAE Fieber and LEPTOPODAE
Fieber)

ii. Posterior coxae rotating.

j. Claws preapical; aquatic forms. GERRIDAE and
VELIADAE

jj. Claws apical.

k. Prosternum without stridulatory sulcus (notch for
beak).

l. Tarsus with three segments; membrane with two
or three longitudinal cells from which veins
radiate; rarely with free longitudinal veins
(Arachnocoris) or veins nearly obsolete
(Arbela); clavus and corium coriaceous; ocelli
rarely absent. NABIDAE

REDUVIOLUS (= CORISCUS) SUBCOLEOPTRATUS (fig. 19
g), a species belonging to this family,
occurring in the United States, has been
accused of biting man. This insect is flat,
of a jet black color, bordered with yellow
on the sides of the abdomen, and with
yellowish legs. It is predaceous, feeding on
other insects.

ll. With other combinations of characters.
HYDROMETRIDAE, HENICOCEPHALIDAE,
NAEOGEIDAE, MESOVELIADAE, JOPPEICIDAE

kk. Prosternum with stridulatory sulcus (notch for
beak); with three segments, short, strong.

l. Antennae filiform or sometimes more slender
apically, geniculate; wing membrane with two
or three large basal cells; scutellum small or
moderate/ REDUVIIDAE

For a key to the genera and species see next
page.

ll. Last antennal segment clavate or fusiform; win
membrane with the veins often forked and
anastomosing; scutellum large; tarsi each with
two segments; fore legs strong. (= PHYMATIDAE)
MACROCEPHALIDAE

ee. Clavus noticeably narrowed towards the apex, never extending
beyond the scutellum, the two not meeting to form a
commissure; head horizontal, much prolonged between the
antennae, on each side with an antennal tubercle, sometimes
acute; ocelli absent; meso- and metasternum simple; tarsi
each with two segments; body flattened (fig. 19c). ARADIDAE,
including DYSODIIDAE.

dd. Pulvilli present (absent in one Australian family
THAUMATOCORIDAE in which case there is a membranous
appendage at the tip of the tibia). CAPSIDAE (=
MIRIDAE),[G] _Eotrechus_ (in family GERRIDAE),
NAEOGAIDAE, TINGITIDAE, PIESMIDAE, MYODOCHIDAE,
CORIZIDAE, COREIDAE, ALYDIDAE, PENTATOMIDAE,
SCUTELLERIDAE, etc.

bb. Apex of head directed ventrally, beak arising from the hinder part
of the lower side of the head; sides of face contiguous to the
front coxae; first pair of wings, when present, of uniform
thickness. Cicadas, scale insects, plant lice (Aphids),
spittle-insects, leaf hoppers, etc. HOMOPTERA

REDUVIIDAE OF THE UNITED STATES

(Adapted from a key given by Fracker).

a. Ocelli none; wings and hemelytra always present in the adults; no
discoidal areole in the corium near the apex of the clavus.
_Orthometrops decorata_, _Oncerotrachelus acuminatus_, etc.,
Pennsylvania and south. _Sarcinae_

aa. Ocelli present in the winged individuals; anterior coxae not as long
as the femora.

b. Hemelytra without a quadrangular or discoidal areole in the corium
near the apex of the clavus.

c. Ocelli not farther cephalad than the caudal margins of the eyes;
segment two of the antenna single.

d. Thorax usually constricted caudad of the middle; anterior coxae
externally flat or concave. PIRATINAE

e. Middle tibiae without spongy fossa, head long, no lateral
tubercle on neck. _S. stria_, Carolina, Ill., Cal.
_Sirthenia_ Spinola

ee. Middle tibiae with spongy fossa; fore tibiae convex above;
neck with a small tubercle on each side.

f. Apical portion of anterior tibiae angularly dilated beneath,
the spongy fossa being preceded by a small prominence.
MELANOLESTES Stal

g. Black, with piceous legs and antennae. N. E. States (fig.
19a) M. PICIPES

gg. Sides, and sometimes the whole dorsal surface of the
abdomen red. Ill., and southward. M. ABDOMINALIS

ff. Tibiae not dilated as in "f"; spongy fossa elongate;
metapleural sulci close to the margin. R. BIGUTTATUS (fig.
22). South RASAHUS A. and S.

dd. Thorax constricted in the middle or cephalad of the middle;
anterior tarsi each three-segmented.

e. Apex of the scutellum narrow, without spines or with a single
spine REDUVIINAE

f. Antennae inserted in the lateral or dorso-lateral margins of
the head; antenniferous tubercles slightly projecting from
the sides of the head; head produced strongly cephalad;
ocelli at least as far apart as the eyes.

g. Antennae inserted very near the apex of the head; segments
one and three of the beak short, segment two nearly four
times as long as segment one. R. PROLIXUS. W. I.
RHODNIUS Stal

gg. Antennae inserted remote from the vertex of the head.

h. Body slightly hairy; pronotum distinctly constricted;
angles distinct; anterior lobe four-tuberculate, with
the middle tubercles large and conical. _M.
phyllosoma_, large species from the southwest.
_Meccus_ Stal

hh. Body smooth, margin of the pronotum sinuous, scarcely
constricted; anterior lobe lined with little
tubercles. CONORHINUS Lap.

i. Surface of the pronotum and prosternum more or less
granular.

j. Eyes small, head black; body very narrow, a fifth
as wide as long; beak reaches the middle of the
prosternum. California. C. PROTRACTUS

jj. Eyes large, head fuscous; body at least a fourth
as wide as long. Southern species. _C.
rubrofasciatus_

ii. Pronotum and prosternum destitute of granules.

j. Border of abdomen entirely black except for a
narrow yellowish spot at the apex of one segment.
Texas. _C. gerstaeckeri_

jj. Border of abdomen otherwise marked.

k. Beak slender, joints one and two slightly pilose,
two more than twice as long as one; tubercles at
the apical angles of the pronotum slightly
acute, conical. Md. to Ill. and south. The
masked bed bug hunter (fig. 71). C. SANGUISUGUS

kk. Beak entirely pilose, joint two a third longer
than joint one; joint one much longer than
three; tubercles at the apical angles of
pronotum slightly elevated, obtuse. Ga., Ill.,
Tex., Cal. _C. variegatus_

ff. Antenna inserted on top of the head between margins, close
to the eyes; antenniferous tubercles not projecting from
the side of the head.

g. Anterior lobe of the pronotum with a bispinous or
bituberculate disc; femora unarmed. _S. arizonica_, _S.
bicolor_. Southwestern species. _Spiniger_ Burm.

gg. Disc of pronotum unarmed; apex of scutellum produced
into a spine; ocelli close to the eyes; eyes large and
close together. REDUVIUS Lamarck

h. Color piceous. Widely distributed in the United States.
(Fig. 20). R. PERSONATUS

hh. More or less testaceous in color. Southwestern states.
R. SENILIS

ee. Apex of scutellum broad, with two or three spines.
ECTRICHODIINAE

f. First segment of the antenna about as long as the head. _E.
cruciata_ Pa. and south; _E. cinctiventris_, Tex. and Mex.
_Ectrichodia_ L. et S.

ff. First segment of the antennae short. _P. aeneo-nitens_.
South. _Pothea_ A. et S.

cc. Ocelli cephalad of the hind margins of the eyes; first segment
of the antennae stout, second segment divided into many smaller
segments. South and west. _Homalocoris maculicollis_, and
_Hammatocerus purcis_. HAMMATOCERINAE

bb. Hemelytra with a quadrangular or discoidal areole in the corium
near the apex of the clavus (fig. 159e).

c. Anal areole of the membrane not extending as far proximad as the
costal areole; basal segment of the antenna thickened, porrect;
the other segments slender, folding back beneath the head and
the first segment STENOPODINAE

d. Head armed with a ramous or furcate spine below each side,
caudad of the eyes.

e. First segment of the antenna thickened, apex produced in a
spine beyond the insertion of the second segment. Species
from Va., Ill. and south. _Pnirontis_ Stal.

ee. First segment of the antenna not produced beyond the
insertion of the second segment. _Pygolampis_, N. E. states
and south; _Gnathobleda_, S. W. and Mex.

dd. Head unarmed below or armed with a simple spine; rarely with a
subfurcate spine at the side of the base. Carolina, Missouri
and south. _Stenopoda_, _Schumannia_, _Diaditus_, _Narvesus_,
_Oncocephalus_

cc. Anal areole of membrane extending farther proximad than the
costal areole.

d. Ocelli farther apart than the eyes. _A. crassipes_, widely
distributed in the United States; other species occur in the
southwest. _Apiomerus_ Hahn.

dd. Ocelli not so far apart as the eyes. ZELINAE

e. Sides of mesosternum without a tubercle or fold in front.

f. Fore femur as long as or longer than the hind femur; first
segment of the beak much shorter than the second. _Z.
audax_, in the north eastern states; other species south
and west. _Zelus_ Fabr.

ff. Fore femur shorter than the hind femur, rarely of equal
length, in this case the first segment of the beak as long
or longer than the second.

g. First segment of the beak shorter than the second; fore
femur a little shorter than the hind femur; the first
segment of the beak distinctly longer than the head
before the eyes. _P. cinctus_ a widely distributed
species (fig. 160). _P. punctipes_, _P. spinicollis_,
Cal., Mex. (= _Milyas_) _Pselliopus_ Berg.

gg. First segment of the beak as long or longer than the
second.

h. Pronotum armed with spines on the disc.

i. Juga distinctly prominent at the apex and often acute
or subacute; fore femur distinctly thickened;
hemelytra usually not reaching the apex of the
abdomen. _Fitchia aptera_, N. Y., south and west;
_F. spinosula_, South; _Rocconata annulicornis_,
Texas, etc.

ii. Juga when prominent, obtuse at apex; eyes full width
of the head; fore femur not thickened; pronotum with
four spines on posterior lobe. _R. taurus_, Pa.,
south and west. _Repipta_ Stal.

hh. Pronotum unarmed on the disc.

i. Spines on each apical angle of the penultimate
abdominal segment. _A. cinereus_, Pa., and south.
_Atrachelus_ A. et S.

ii. Apical angle of the penultimate abdominal segment
unarmed. _Fitchia_ (in part); _Castolus ferox_,
Arizona.

ee. Sides of the mesosternum with a tubercle or fold in front at
the hind angles of the prosternum; first segment of the beak
longer than the part of the head cephalad of the eyes.

f. Fore femur thickened, densely granulated; hind femur
unarmed.

g. Fore tibiae each with three long spines on the ventral
side. _S. diadema_ (fig. 159e), a widely distributed
species; and several southwestern species. _Sinea_ A. et
S.

gg. Fore tibiae unarmed. _A. multispinosa_, widely
distributed; _A. tabida_, Cal. _Acholla_ Stal.

ff. Fore femur unarmed, rarely a little thickened, a little
granulated.

g. Pronotum produced caudad over the scutellum, with a high
mesal tuberculate ridge (fig. 19e). A. CRISTATUS. N. Y.
to Cal. and south. ARILUS Hahn.

gg. Caudal lobe of the pronotum six sided, neither elevated
nor produced caudad. _H. americanus_, Southwest; also
several W. I. and Mexican genera. HARPACTOR Lap.

DIPTERA (Mosquitoes, Midges, Flies)

a. Integument leathery, abdominal segments indistinct; wings often
wanting; parasitic forms. PUPIPARA

b. Head folding back on the dorsum of the thorax; wingless flies
parasitic on bats. Genus _Nycteribia_. NYCTERIBIIDAE

bb. Head not folding back upon the dorsum of the thorax; flies either
winged or wingless; parasitic on birds and on bats and other
mammals.

c. Antennae reduced, wings when present, with distinct parallel veins
and outer crossveins; claws simple; palpi leaf-like, projecting
in front of the head. Flies chiefly found on bats. Several
genera occur in North America. STREBLIDAE

cc. Antennae more elongate, segments more or less distinctly
separated; head sunk into an emargination of the thorax; wings
when present with the veins crowded toward the anterior margin;
palpi not leaf-like. HIPPOBOSCIDAE

d. Wings absent or reduced and not adapted for flight.

e. Wings and halteres (balancers) absent. _M. ovinus_, the sheep
tick. _Melophagus_ Latr.

ee. Wing reduced (or cast off), halteres present.

f. Claw bidentate; ocelli present. On deer after the wings are
cast off. _L. depressa_. _Lipoptena_ Nitsch

ff. Claw tridentate (fig. 161 f). On _Macropis_. _B.
femorata._ _Brachypteromyia_ Will.

dd. Wings present and adapted for flight.

e. Claws bidentate.

f. Ocelli present; head flat; wings frequently cast off. On
birds before casting of the wing. _Lipoptena_ Nitsch.

ff. Ocelli absent; head round; wings present. The horse tick
H. EQUINA may attack man (fig. 162). HIPPOBOSCA L.

ee. Claws tridentate (fig. 161 f.).

f. Anal cell closed at apical margin by the anal crossvein.

g. Ocelli absent. _Stilbometopa_ Coq.

gg. Ocelli present.

h. R_{4+5} does not form an angle at the crossvein. On
birds. There is a record of one species of this genus
attacking man. ORNITHOMYIA Latr.

hh. R_{4+5} makes an angle at the crossvein. _O.
confluens_. _Ornithoica_ Rdi.

ff. Anal cell not closed by an anal crossvein. _Lynchia_,
_Pseudolfersia_, and _Olfersia_ are chiefly bird
parasites. The first mentioned genus is said to be the
intermediate host of _Haemoproteus columbae_.

aa. Abdominal segments chitinous; not parasitic in the adult stage.

b. Antennae with six or more segments and empodium not developed
pulvilliform; palpi often with four segments.

c. Ocelli present. BLEPHAROCERIDAE, RHYPHIDAE, BIBIONIDAE,
MYCETOPHILIDAE, besides some isolated genera of other families.

cc. Ocelli absent.

d. Dorsum of the thorax with a V-shaped suture; wings usually with
numerous veins; legs often very long and slender. Crane flies.
TIPULIDAE

dd. Dorsum of the thorax without a V-shaped suture.

e. Not more than four longitudinal veins ending in the wing
margin; wing usually hairy: antennae slender; coxae not
long; tibiae: without spurs, legs long and slender. Small,
delicate flies often called Gall gnats. CECIDOMYIIDAE.

ee. More than four longitudinal veins ending in the wing margin.

f. The costal vein is not produced beyond the tip of the wing;
radius with not more than three branches.

g. Antennae short, composed of ten or eleven closely united
segments; legs stout; body stout; abdomen oval; anterior
veins stout, posterior ones weak (fig. 163 b); eyes of
the male contiguous over the antennae. Black flies,
buffalo flies, turkey gnats. Many North American
species, several of them notorious for their blood
sucking propensities. SIMULIIDAE

h. Second joint of the hind tarsus with basal scale-like
process and dorsal excision (fig. 161 h); radial
sector not forked; no small cell at the base of the
wing. _S. forbesi_, _jenningsi_, _johannseni_,
_meridionale_, _piscicidium_, VENUSTUM, VITTATUM, etc.
Widely distributed species (= EUSIMULIUM) SIMULIUM
Latr.

hh. No basal scale-like process on the second joint of the
hind tarsus; radial sector usually forked (fig. 163
b).

i. Face broad, small basal cell of the wing present. _P.
fulvum_, HIRTIPES, _mutatum_, PECUARUM, _pleurale_.
PROSIMULIUM Roub.

ii. Face linear; small basal cell of the wing absent.
One species, _P. furcatum_, from California.
_Parasimulium_ Malloch

gg. Flies of a different structure.

h. Antennae composed of apparently two segments and a
terminal arista formed of a number of closely united
segments. Rare flies with aquatic larvae.
ORPHNEPHILIDAE

hh. Antennae of six to fifteen segments, those of the male
usually plumose; legs frequently slender and wings
narrow. CHIRONOMIDAE

i. Media forked (except in the European genus
_Brachypogon_); thorax without longitudinal fissure
and not produced over the head (except in four
exotic genera); antennae usually fourteen-jointed in
both sexes; fore tibia with a simple comb of setulae,
hind tibia with two unequal combs, middle tibia
without comb. CERATOPOGONINAE

j. Thorax produced cap-like over the head, wing narrow
and very long. _Jenkinsia_, _Macroptilum_ and
_Calyptopogon_, eastern hemisphere;
_Paryphoconus_, Brazil.

jj. Thorax not produced over the head.

k. Eyes pubescent, empodium well developed, or if
short then R_{2+3} distinct and crossvein-like
or the branches of R coalescent; r-m crossvein
present; fore femora not thickened; wing either
with appressed hairs or with microscopic erect
setulae. _Dasyhelea_ Kieff.

kk. Eyes bare, or otherwise differing from the
foregoing.

l. Empodium well developed, nearly as long as the
claws and with long hairs at the base; femora
and fifth tarsal segments unarmed, i.e.
without spines or stout setae; fourth tarsal
segment cylindrical.

m. Wing with erect and microscopic setulae.
Widely distributed. (= Atrichopogon)
_Ceratopogon_ Meig.

mm. Wing with long and depressed hairs. Widely
distributed. _Forcipomyia_

n. Hind metatarsus shorter or not longer than
the following (i.e. the second tarsal)
segment. Subgenus _Prohelea_ Kieff

nn. Hind metatarsus longer than the following
segment. Subgenus _Forcipomyia_ Meig.

ll. Empodium short, scarcely reaching the middle
of the claws, or vestigial.

m. R-m crossvein wanting.

n. Palpi four segmented; inferior fork of the
media obliterated at the base. Australia.
_Leptoconops_ Skuse

nn. Palpi three-segmented.

o. Legs spinulose, tarsal claws of the
female with a basal tooth or strong
bristle, those of the male unequal, the
anterior with a long sinuous tooth, the
posterior with a short arcuate tooth.
Italy. MYCTEROTYPUS Noe

oo. Legs unarmed; no crossvein between the
branches of the radius (fig. 163e). New
Mexico. TERSESTHES Townsend

mm. R-m crossvein present.

n. Fore femora very much swollen, armed with
spines below, fore tibia arcuate and
applied closely to the inferior margin of
the femur.

o. R_{2+3} present, therefore cell R_1 and
R_2 both present; wing usually fasciate.
United States _Heteromyia_ Say.

oo. R_{2+3} not distinct from R_{4+5}, hence
cell R_3 obliterated. South America
_Pachyleptus_ Arrib. (Walker)

nn. Fore femur not distinctly swollen.

o. R_{2+3} present therefore cells R_1 and
R_3 both present, or if not, then the
branches of the radius more or less
coalescent, obliterating the cells.

p. At least the tip of the wing with erect
setulae; tip of R_{4+5} scarcely
attaining the middle of the wing,
empodium rather indistinct, not
reaching the middle of the claws, the
claws not toothed, equal, with long
basal bristle; legs without stout
setae. Widely distributed. CULICOIDES
Latr.

HAEMATOMYIDIUM and OECACTA are probable
synonyms of this.

pp. Wings bare, if rarely with hair, then
the radius reaches beyond two-thirds
the length of the wing, or the femur
or fifth tarsal segment with stout
black spines.

q. Media unbranched. Europe.
_Brachypogon_ Kieff

qq. Media branched.

r. Hind femur much swollen and spined.
America and Europe. _Serromyia_
Meg.

rr. Hind femur not distinctly swollen.

s. Cell R_1 not longer than high;
fork of the media distad of the
crossvein; wing with microscopic
setulae. _Stilobezzia_ Kieff

ss. Cell R_1 elongate.

t. Femora unarmed. Widely
distributed. (= Sphaeromias
Kieff. 1913 not Curtis?).
JOHANNSENIELLA Will.

tt. Femora, at least in part, with
strong black spines. Widely
distributed. _Palpomyia_
Megerle

oo. R_{2+3} coalescent with R_{4+5} hence
cell R_3 is obliterated.

p. In the female the lower branch of the
media with an elbow near its base
projecting proximad, the petiole of
the media coalescent with the basal
section of the radius, wing long and
narrow, radial sector ending near the
tip of the wing; venation of the male
as in _Bezzia_; front concave. United
States. _Stenoxenus_ Coq.

pp. Venation otherwise, front not concave.