Chapter I: Part 1

Transcriber's Notes:

The original spelling and minor inconsistencies in the spelling and formatting have been maintained.

Corrections applied to the original text have been listed at the end of the text.

The ligature oe and OE has been marked as [oe] and [OE].

Formatting:

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SMITHSONIAN INSTITUTION.
UNITED STATES NATIONAL MUSEUM.

DIRECTIONS FOR COLLECTING AND PRESERVING INSECTS.

BY

C. V. RILEY, M. A., PH. D.,
_Honorary Curator of the Department of Insects, U. S. National Museum._

Part F of Bulletin of the United States National Museum, No. 39
(with one plate).

WASHINGTON:

GOVERNMENT PRINTING OFFICE.

1892.

=CONTENTS.=

Page.
INTRODUCTORY 3
MANUAL OF INSTRUCTIONS FOR COLLECTING AND PRESERVING INSECTS 5
CHARACTERISTICS OF INSECTS 5
SCOPE AND IMPORTANCE OF ENTOMOLOGY 6
CLASSIFICATION OF HEXAPODS 8
Order Hymenoptera 12
Order Coleoptera 14
Order Lepidoptera 16
Order Hemiptera 17
Suborder Thysanoptera 18
Order Diptera 19
Suborder Aphaniptera 20
Order Orthoptera 21
Suborder Dermaptera 22
Order Neuroptera 22
Suborder Trichoptera 23
Suborder Mecoptera 23
Suborder Neuroptera 23
Suborder Platyptera 24
Suborder Plecoptera 25
Suborder Odonata 25
Suborder Ephemeroptera 25
Suborder Thysanura 26
COLLECTING 26
General considerations 26
Collecting apparatus 29
The sweeping net 29
The water net 31
Water dip-net 32
The umbrella 32
The beating cloth 33
The umbrella net 34
The sieve 35
The chisel 36
The trowel 36
The collecting tweezers 36
The brush 37
The fumigator 38
The haversack 38
The lens and microscope 39
Collecting Hymenoptera 39
Collecting Coleoptera 42
General directions 42
Winter collecting 43
Spring collecting 44
Myrmecophilous and Termetophilous species 44
Spring flights of Coleoptera 44
Beach collecting 45
Attracting by lights 45
Traps 45
Freshet 45
Summer collecting 46
Collecting under stones 46
Collecting in rotten stumps and logs 46
Collecting in dying or dead trees 47
Beating living trees, shrubs, and vines 47
Sweeping 47
Collecting on mud and gravel banks 48
Collecting aquatic beetles 49
Collecting at the seashore and on sandy places 49
Collecting dung beetles 49
Night collecting 50
Fall collecting 50
Collecting Lepidoptera 50
Collecting the adults 50
Collecting the early states 53
Collecting Hemiptera 54
Collecting Diptera 55
Collecting Orthoptera 57
Collecting Neuroptera 58
Pseudoneuroptera 58
Neuroptera 59
KILLING AND PRESERVING INSECTS 60
First preservation of living specimens 60
Killing specimens 61
Alcohol 61
Chloroform and ether 62
Cyanide of potassium 63
Other agents 65
Special directions for different orders 66
ENTOMOTAXY 67
Care of pinned and mounted specimens 67
Insect pins 67
Preparation of specimens 68
Pinning 69
Mounting on points 70
Mounting duplicates 73
Temporary storage of specimens 74
Envelopes for Lepidoptera, etc. 74
Directions for spreading insects 75
A new apparatus for spreading Microlepidoptera 76
Spreading Microlepidoptera 77
Relaxing 79
Inflation of the larvae of Lepidoptera 80
Stuffing insects 82
Dry preservation of Aphides and other soft-bodied insects 82
Mounting specimens for the microscope 84
Preparing and mounting the wings of Lepidoptera 86
Preservation of alcoholic specimens 88
Apparatus and methods 88
Vials, stoppers, and holders 89
Preserving micro-larvae in alcohol 92
Preservative fluids 93
Alcohol 93
Alcohol and white arsenic 93
Alcohol and corrosive sublimate 94
Two fluids to preserve form and color 94
Glycerin 94
The Wickersheim preserving fluid 94
Labeling specimens 95
General directions 95
Labels for pinned specimens 95
Labeling alcoholic specimens 97
Cabinet for apparatus 98
INSECT BOXES AND CABINETS 98
General directions 98
The folding box 98
The cabinet 100
The Lintner display box 101
The Martindale box for Lepidoptera 104
Horizontal _versus_ vertical arrangement of boxes 104
Lining for insect boxes 104
ARRANGEMENT OF INSECTS IN THE CABINET 106
Systematic and biologic collections 106
Economic displays 106
Labeling collections 107
MUSEUM PESTS, MOLD, ETC 108
Museum pests 108
Remedies 109
Naphthaline 109
Bisulphide of carbon 110
Mercury pellets 110
Carbolic acid 110
A means of preserving insects in dry, hot countries 110
Mold 111
Verdigrising and greasing 111
THE REARING OF INSECTS 112
General directions 112
The breeding cage, or vivarium 112
Detailed instructions for rearing 115
The root cage 118
Other apparatus 119
The insectary 120
DIRECTIONS FOR PACKING AND TRANSMITTING INSECTS 121
NOTES AND MEMORANDA 123
INSTRUCTIONS FOR COLLECTING AND PRESERVING ARACHNIDS AND MYRIAPODS 124
Directions for collecting spiders 124
Apparatus 124
Time and locality for collecting 125
Collecting other Arachnids, mites, ticks, scorpions, etc 126
Collecting Myriapoda 130
TEXT BOOKS AND ENTOMOLOGICAL WORKS 131
Comprehensive works most useful for the student of North
American insects 132
General works on classification 132
Hymenoptera 132
Coleoptera 132
Lepidoptera 133
Hemiptera 134
Diptera 134
Orthoptera 135
Neuroptera 135
Myriapoda 135
Arachnida 136
American periodicals 136
Foreign periodicals 138
The more useful works on economic entomology 140
Entomological works published by the United States Entomological
Commission and by the United States Department of Agriculture 141
Works by the United States Entomological Commission 141
Bulletins of the Division of Entomology, U. S. Department of
Agriculture 142
Special reports and bulletins 144
HOW TO OBTAIN ENTOMOLOGICAL BOOKS AND PAMPHLETS 145

INTRODUCTORY.

There is a constant demand, especially from correspondents of the Museum and also of the Department of Agriculture, for information as to how to collect, preserve, and mount insects. There is also great need of some simple directions on a great many other points connected with the proper packing of insects for transmission through the mails or otherwise; labeling; methods of rearing; boxes and cabinets; text-books, etc. Interest in the subject of entomology has, in fact, made rapid growth in the last few years, and now that nearly every State has an official entomologist connected with its State Agricultural Experiment Station, the number of persons interested in the subject may be expected to increase largely in the near future. I have hitherto made use of the Smithsonian Miscellaneous Collections, No. 261, which is a pamphlet on collecting and preserving insects prepared by Dr. A. S. Packard. This is out of print, and I have been requested by Prof. Goode to prepare for Bulletin 39, U. S. N. M., something that would cover the whole ground and give the more essential information needed for collectors and students of insect life. I have deemed it unnecessary to go too much into detail, but have studied not to omit anything essential. Customs and methods vary in different countries and with different individuals, but the recommendations contained in the following pages are based upon my own experience and that of my assistants and many acquaintances, and embrace the methods which the large majority of American entomologists have found most satisfactory.

Much of the matter is repeated bodily from the directions for collecting and preserving insects published in my Fifth Report on the Insects of Missouri (1872) and quotations not otherwise credited are from that Report. The illustrations, also, when not otherwise credited or not originally made for this paper, are from my previous writings. Some are taken from Dr. Packard's pamphlet, already mentioned; others, with the permission of Assistant Secretary Willits, from the publications of the Department of Agriculture, while a number have been especially made for the occasion, either from photographs, or from drawings by Miss L. Sullivan or Dr. Geo. Marx or Mr. C. L. Marlatt. When enlarged, the natural size is indicated in hair-line. In the preparation of the pamphlet I have had the assistance of Mr. E. A. Schwarz, and more particularly of Mr. C. L. Marlatt, to both of whom I desire here to express my obligations.

C. V. R.

MANUAL OF INSTRUCTIONS FOR COLLECTING AND PRESERVING INSECTS.

* * * * *

By C. V. RILEY,
_Honorary Curator of the Department of Insects, U. S. National Museum._

* * * * *

CHARACTERISTICS OF INSECTS.

The term "insect" comes from the Latin _insectum_, and signifies "cut into." It expresses one of the prime characteristics of this class of animals, namely, that of segmentation. This feature of having the body divided into rings or segments by transverse incisions is possessed by other large groups of animals, and was considered of sufficient importance by Cuvier to lead him, in his system of classification, to group with Insects, under the general term Articulata, Worms, Crustacea, Spiders, and Myriapods. Worms differ from the other four groups in having no articulated appendages, and in having a soft body-wall or integument instead of a dense chitinous covering, and are separated as a special class _Vermes_. The other four groups of segmented animals possess in common the feature of jointed appendages and a covering of chitinous plates, and are brought together under the term _Arthropoda_. The division of the body into a series of segments by transverse incisions, characteristic of these animals and these only, justifies the use of Cuvier's old name, Articulates, as this segmented feature represents a definite relationship and a natural division--as much so as the vertebral column in Vertebrates. The Cuvierian name should be retained as a coordinate of Vertebrates, Molluscs, etc., and the terms Vermes and Arthropods may be conveniently used to designate the two natural divisions of the Articulates.

The term "insect" has been employed by authors in two different senses--one to apply to the tracheated animals or those that breathe through a system of air tubes (tracheae), comprising Spiders, Myriapods, and insects proper or Hexapods,[1] and the other in its restricted sense as applied to the Hexapods only. To avoid confusion, the latter signification only should be used, and it will be thus used in this article.

[1] From the Greek [Greek: exapous], having 6 feet.

We see, then, that insects share, in common with many other animals, the jointed or articulated structure. Wherein, then, do they differ? _Briefly, in having the body divided into thirteen joints and a subjoint_, including the head as a joint, and in the adult having six true, jointed legs, and usually, though not always, wings. The five classes of Articulates differ from each other in the number of legs they possess in the adult form, as follows: Hexapoda, 6 legs; Arachnida, 8 legs; Crustacea, 10-14 legs; Myriapoda, more than 14 legs; Vermes, none. This system holds for the adult form only, because some mites (Arachnida) when young have only 6 legs, and many true insects in the larva state either have no legs at all, or have additional abdominal legs which are not jointed, but membranous, and are lost in the perfect or adult state. These are called false or prolegs.

It will serve to make these instructions clear if I at once explain that the life of an insect is marked by four distinct states, viz., the egg, the larva, the pupa, and the imago, and that the last three words will constantly recur. We have no English equivalent for the words larva and pupa, for while some authors have written them with the terminal _e_, so as to get the English plural, yet "larves" and "pupes" so shock the ear that the terms have not been (and deserve not to be) generally adopted.

We have seen that an insect in the final state has six true legs. Yet even here many species depart from the rule, as there are many in which the perfect insect, especially in the female sex, is apodous or without legs, just as there are also other cases where they are without wings. Sometimes the legs seem to be reduced in number by the partial or total atrophy of one or the other pair, but in all these exceptional cases there is no difficulty in realizing that we have to deal with a true insect, because of the other characters pertaining to the class, some of which it will be well to allude to.

Insects are further characterized by having usually three distinct divisions of the body, viz.: head, thorax, and abdomen, and by undergoing certain metamorphoses or transformations. Now, while a number of other animals outside of the insect world go through similar transformations, those in the Crustacea being equally remarkable, yet, from the ease with which they are observed and the completeness of the transformations in most insects, the metamorphoses of this class have, from time immemorial, excited the greatest curiosity.

SCOPE AND IMPORTANCE OF ENTOMOLOGY.

But few words are necessary to indicate the importance of entomology, especially to the farming community; for while insects play a most important part in the economy of nature and furnish us some valuable products and otherwise do us a great deal of indirect good, yet they are chiefly known by the annoyances they cause and by the great injury they do to our crops and domestic animals. Hence some knowledge of insects and how to study them becomes important, almost necessary, to every farmer.

The scope of the science may best be indicated by a statement of the number of species existing, as compared with other animals. The omnipresence of insects is known and felt by all; yet few have any accurate idea of the actual numbers existing, so that some figures will not prove uninteresting in this connection. Taking the lists of described species, and the estimates of specialists in the different orders, it is safe to say that about thirty thousand species have already been described from North America, while the number of species already described or to be described in the Biologia Centrali-Americana, i. e., for Central America, foot up just about the same number, Lord Walsingham having estimated them at 30,114 in his address as president of the London Entomological Society two years ago, neither the Orthoptera nor the Neuroptera being included in this estimate. By way of contrast the number of mammals, birds, and reptiles to be described from the same region, is interesting. It foots up 1,937, as follows:

Mammals, 180; birds, 1,600; reptiles, 157.

If we endeavor to get some estimate of the number of insects that occur in the whole world, the most satisfactory estimates will be found in the address just alluded to, and in that of Dr. David Sharp before the same society. Linnaeus knew nearly 3,000 species, of which more than 2,000 were European and over 800 exotic. The estimate of Dr. John Day, in 1853, of the number of species on the globe, was 250,000. Dr. Sharp's estimate thirty years later was between 500,000 and 1,000,000. Sharp's and Walsingham's estimates in 1889 reached nearly 2,000,000, and the average number of insects annually described since the publication of the Zoological Record, deducting 8 per cent for synonyms, is 6,500 species. I think the estimate of 2,000,000 species in the world is extremely low, and if we take into consideration the fact that species have been best worked up in the more temperate portions of the globe, and that in the more tropical portions a vast number of species still remain to be characterized and named, and if we take further into consideration the fact that many portions of the globe are yet unexplored, entomologically, that even in the best worked up regions by far the larger portion of the Micro-Hymenoptera and Micro-Diptera remain absolutely undescribed in our collections, and have been but very partially collected, it will be safe to estimate that not one-fifth of the species extant have yet been characterized or enumerated. In this view of the case the species in our collections, whether described or undescribed, do not represent perhaps more than one-fifth of the whole. In other words, to say that there are 10,000,000 species of insects in the world, would be, in my judgment, a moderate estimate.

CLASSIFICATION OF HEXAPODS.

Seven orders of insects were originally recognized by Linnaeus, namely, Neuroptera, Diptera, Hemiptera, Lepidoptera, Coleoptera, Hymenoptera, and Aptera. This classification was based on the organs of flight only, and while in the main resulting in natural divisions which still furnish the basis of more modern classifications, was faulty in several particulars. For instance, the Aptera, which included all wingless insects, was soon found to be a very unnatural assemblage and its components were distributed among the other orders. The establishment of the order Orthoptera by Olivier to include a large and well-defined group of insects associated with the Hemiptera by Linnaeus, restored the original seven orders, and this classification has, in the main, been followed by entomologists up to the present time.

All insects are, in a broad way, referable to one or the other of these seven primary orders by the structure of the wings and the character of the mouth-parts in the imago, and by the nature of their transformations.

Some of these orders are connected by aberrant and osculant families or groups, which have by other authors been variously ranked as independent orders, but which, following Westwood substantially, I have considered, for convenience, as suborders. (_See_ Fifth Report, Insects of Missouri, etc., 1872.)

In the article just cited, I made use of the accompanying diagram in the form of a pyramid (Fig. 1), which gives a graphic representation of the distinguishing characters and the relative rank as usually accepted, of the orders and suborders.

Full discussion of the different classifications is unnecessary in this connection. Authors have differed in the past and will differ in the future as to what constitutes a natural system, and it would require many pages to give even a brief survey of the various schemes that have been proposed. As I have elsewhere said, "We must remember that classifications are but a means to an end--appliances to facilitate our thought and study--and that, to use Spencer's words, 'we cannot, by any logical dichotomies, actually express relations which in nature graduate into each other insensibly.'"

The most philosophical, perhaps, of the more modern systems of classification is that of Friedrich Brauer, who has carefully studied the subject, and has given us an arrangement consisting of sixteen orders. This has many merits and has been adopted, with slight modifications, by Packard in his "Entomology for Beginners," and by Hyatt and Arms in their recent and valuable text-book "Insecta." Comstock, in his "Introduction to Entomology" strongly recommends Brauer's classification, but for reasons of simplicity and convenience adheres to a modification of the old classification of Westwood.

For purposes of comparison the classification by Hyatt and Arms, which is substantially that of Brauer, may be introduced.

In linear arrangement it is as follows:

I. Thysanura (_Spring-tails_, etc.).
II. Ephemeroptera (_Ephemeridae_; May-flies). (=_Plectoptera_ Pack.)
III. Odonata (_Libellulidae_; Dragon-flies).
IV. Plecoptera (_Perlidae_; Stone-flies).
V. Platyptera (_Termites_, _Mallophaga_, etc.).
VI. Dermaptera (_Forficulidae_; Earwigs).
VII. Orthoptera (Locusts, Grasshoppers, etc.).
VIII. Thysanoptera (_Thripidae_; Fringe-wings).
IX. Hemiptera (Bugs).
X. Coleoptera (Beetles).
XI. Neuroptera (_Sialidae_, _Hemerobiidae_; Lace-wings, etc.).
XII. Mecoptera (_Panorpidae_; Scorpion-flies).
XIII. Trichoptera (_Phryganeidae_; Caddis-flies).
XIV. Lepidoptera (Butterflies and Moths).
XV. Hymenoptera (Bees, Wasps, etc.).
XVI. Diptera (Two-winged flies).

The relationship of these orders cannot be indicated in a linear arrangement, and is admirably shown by Hyatt and Arms by means of diagrams which I reproduce (Figs. 2, 3.)

The relation of these sixteen orders to the older, septenary scheme is shown by the following arrangement:

1. Hymenoptera Hymenoptera XV.

2. Coleoptera Coleoptera X.

3. Lepidoptera Lepidoptera XIV.

{Homoptera.
4. Hemiptera {Hemiptera IX. {Heteroptera.
{Thysanoptera VIII.

5. Diptera {Diptera XVI. {Including Aphaniptera or Siphonaptera
{of some authors.

6. Orthoptera {Orthoptera VII.
{Dermaptera VI.

{Trichoptera XIII }
{Mecoptera XII }Neuroptera.
{Neuroptera XI }
7. Neuroptera {Platyptera V }
{Plecoptera IV }
{Odonata III }Pseudo-neuroptera.
{Ephemeroptera II }
{Thysanura I }

It will be seen that the changes are not so great as would at first appear. The three more important orders, namely, the Hymenoptera, Coleoptera, and Lepidoptera, remain substantially the same in all classifications, and so with the three orders next in importance--the Hemiptera, Diptera, and Orthoptera. All that has been done with these three has been to rank as separate orders what by former authors were preferably considered as either families or suborders. The principal change is in the Neuroptera, of which no less than eight orders have been made. This is not to be wondered at, because the order, as formerly construed, was conceded to be that which represents the lowest forms and more synthetic types of insects, and as such necessarily contained forms which it is difficult to classify definitely.

In the discussion of the characteristics, habits, number of species, and importance of the several groups, I follow, with such changes as the advances in the science of entomology have made necessary, the arrangement shown in Fig. 1.

"Order HYMENOPTERA ([Greek: ymen], a membrane; [Greek: pteron], wing). Clear or Membrane-winged Flies: Bees, Wasps, Ants, Saw-flies, etc. Characterized by having four membranous wings with comparatively few veins, the hind part smallest. The transformations are complete: _i. e._, the larva bears no resemblance to the perfect insect.

"Some of the insects of this order are highly specialized, and their mouth-parts are fitted both for biting and sucking, and in this respect they connect the mandibulate and haustellate insects. The common Honey-bee has this complex structure of the mouth, and if the editors of our agricultural papers would bear the fact in mind, we should have less of the never-ending discussion as to whether bees are capable of injuring fruit at first hand. The lower lip (_labium_) is modified into a long tongue, sheathed by the lower jaws (_maxillae_), and they can sip, or, more properly speaking, lap up nectar; while the upper jaws (_mandibulae_), though not generally used for purposes of manducation, are fitted for biting and cutting. The Hymenoptera are terrestrial, there existing only a very few degraded, swimming forms.

"This order is very naturally divided into two sections--the ACULEATA and TEREBRANTIA. The aculeate Hymenoptera, or Stingers, comprise all the families in which the abdomen in the female is armed with a sting connected with a poison reservoir, and may be considered the typical form of the order, including all the social and fossorial species. The insects of this section must be considered essentially beneficial to man, notwithstanding the occasional sting of a bee or wasp, the boring of a carpenter bee, or the importunities of the omnipresent ant. Not only do they furnish us with honey and wax, but they play so important a part in the destruction of insects injurious to vegetation that they may be looked upon as God-appointed guards over the vegetal kingdom--carrying the pollen from plant to plant, and insuring the fertilization of di[oe]cious species, and the cross-fertilization of others; and being ever ready to clear them of herbivorous worms which gnaw and destroy. The whole section is well characterized by the uniformly maggot-like nature of the larva. The transformations are complete, but the chitinous larval covering is often so very thin and delicate that the budding of the members, or gradual growth of the pupa underneath, is quite plainly visible, and the skin often peels off in delicate flakes, so that the transition from larva to pupa is not so marked and sudden as in those insects which have thicker skins.

"The terebrantine Hymenoptera, or Piercers, are again divisible into two subsections: first, the ENTOMOPHAGA, which are, likewise, with the exception of a few gall-makers, beneficial to man, and include the parasitic families, and the gall-flies; second, the PHYTOPHAGA, comprising the Horn-tails (_Uroceridae_), and the Saw-flies (_Tenthredinidae_), all of which are vegetable feeders in the larval state, those of the first family boring into trees, and those of the second either feeding externally on leaves or inclosed in galls. They are at once distinguished from the other Hymenoptera by the larvae having true legs, which, however, in the case of the Horntails, are very small and exarticulate. The larvae of many Saw-flies have, besides, prolegs, which are, however, always distinguishable from those of Lepidopterous larvae by being more numerous and by having no hooks.

"Order COLEOPTERA ([Greek: koleos], a sheath; [Greek: pteron], wing). Beetles or Shield-winged Insects. Characterized by having four wings, the front pair (called _elytra_) horny or leathery, and usually united down the back with a straight suture when at rest, the hind ones membranous and folded up under the elytra when at rest. Transformations complete.

"This is an order of great importance, and in the vast number and diversity of the species comprised in it outranks any of the others. The ease with which the insects of this order are obtained and preserved make it one of the most attractive to the amateur, and beetles are, perhaps, of all insects, the best known and understood in the popular mind. For the same reason they have, in the perfect state, received most attention from the entomologists, but their transformations and preparatory forms yet offer a wide and inviting field for the student. The simplest and best-known classification of the beetles is the tarsal system, founded on the number of joints to the tarsi, by which we get four great sections: (1) PENTAMERA, in which all the tarsi are 5-jointed; (2) HETEROMERA, with the four anterior 5-jointed and the two posterior 4-jointed; (3) PSEUDO-TETRAMERA, with apparently only four joints to all the tarsi, though, in reality, there is a fifth penultimate joint, diminutive and concealed; (4) PSEUDO-TRIMERA, with apparently only three joints to all the tarsi. This system, like most others, is not perfect, as there are numerous species not possessing five joints to the tarsi belonging to the first section; and for practical purposes beetles may be very well arranged according to habit. We thus get, first, the ADEPHAGA, or carnivorous species, including all those which prey on other living insects, and to which, following Mr. Walsh, I have, for obvious reasons, applied the suggestive term 'Cannibal'; second, the NECROPHAGA, comprising those which feed on carrion, dung, fungi, and decaying vegetation; third, the PHYTOPHAGA, embracing all those feeding on living vegetation. This arrangement is by no means perfect, for there are beetles which are carnivorous in the larva and herbivorous in the imago state; while some of the NECROPHAGA are actually parasitic. Yet, it is not more artificial than others which have been proposed. The carnivorous species, broadly speaking, are _Pentamerous_, the only striking exception being the Coccinellidae (Lady-birds), which are _Pseudo-trimerous_. The carrion-feeders are also _Pentamerous_; but vegetable-feeders are found in all the tarsal divisions, though the _Pseudo-tetramera_ are the more essentially herbivorous, and consequently the most injurious."

"Order LEPIDOPTERA ([Greek: lepis], a scale; [Greek: pteron], wing). Butterflies and Moths, or scaly-winged insects. Characterized by having four branching-veined membranous wings, each more or less densely covered on both sides with minute imbricated scales which are attached by a stalk, but which easily rub off, and appear to the unaided eye like minute particles of glistening dust or powder. Transformations complete.

"Next to the Lepidoptera, the Coleoptera are, perhaps, most familiar to the popular mind. Every one admires the beauty of these frail creatures, dressed in every conceivable pattern, and adorned with every conceivable color, so as to rival the delicate hues of the rainbow, and eclipse the most fantastic and elaborate designs of man. When magnified, the scales, to which this beauty of pattern and color is entirely due, present all manner of shapes, according to the particular species or the particular part of the individual from which they are taken. According to Lewenhoeck, there are 400,000 of these scales on the wing of the common silkworm.

"The transformations of these insects are complete, and the changes are usually so sudden and striking as to have excited the wonder and admiration of observers from earliest times.

"The more common form of the larva is exampled in the ordinary caterpillar--a cylindrical worm with a head, twelve joints and a sub-joint; six thoracic or true legs, four abdominal and two anal prolegs. But there is a great variety of these larvae, some having no legs whatever, some having only the jointed legs, and others having either four, six, eight, or ten, but never more than ten prolegs. With few exceptions they are all vegetable-feeders, and with still fewer exceptions, terrestrial. The perfect insects make free use of their ample wings, but walk little; and their legs are weak, and not modified in the various ways so noticeable in other orders, while the front pair in some butterflies are impotent.

"As an order this must be considered the most injurious of the seven.

"A convenient system of classification for the Lepidoptera is based on the structure of the antennae. By it we get two great sections: 1st, Butterflies (RHOPALOCERA); 2d, Moths (HETEROCERA), which latter may again be divided into Crepuscular and Nocturnal Moths. Butterflies are at once distinguished from moths by their antennae being straight, stiff and _knobbed_, and by being day-fliers or diurnal; while moths have the antennae tapering to a point, and are, for the most part, night-flyers or nocturnal. The crepuscular moths, composed mostly of the Sphinges or Hawk-moths, hover over flowers at eve, and connect the two sections not only in habit, but in the character of the antennae which first thicken toward the end, and then suddenly terminate in a point or hook.

"Order HEMIPTERA ([Greek: hemi], half; [Greek: pteron], wing), Bugs. The insects of this order are naturally separated into two great sections; 1st, Half-winged Bugs, or HETEROPTERA ([Greek: heteros], different; [Greek: pteron], wing) having the basal half of the front wings (called _hemelytra_) coriaceous or leathery, while the apical part is membranous. The wings cross flatly over the back when at rest; 2d, Whole-winged Bugs, or HOMOPTERA ([Greek: homos], equal; [Greek: pteron], wing), having all four wings of a uniform membranous nature and folding straight down the back when at rest. The latter, if separated, may be looked upon as a Suborder.

"Transformations incomplete; _i. e._, the larvae and pupae have more or less the image of the perfect insect, and differ little from it except in lacking wings.

"The genuine or half-winged Bugs (Figs. 18 and 19) are usually flattened in form, when mature; though more rounded in the adolescent stages. They may be divided into Land Bugs (_Aurocorisa_) and Water Bugs (_Hydrocorisa_). The species of the first division very generally possess the power of emitting, when disturbed or alarmed, a nauseous, bed-buggy odor, which comes from a fluid secreted from two pores, situated on the under side of the metathorax. Such well-known insects as the Bed-bug and Chinch-bug belong here. The habits of the species are varied, and while some are beneficial, others are quite injurious to man.

"The Whole-winged Bugs (Figs. 20 and 21), on the contrary, are all plant-feeders, and with the exception of a few, such as the Cochineal and Lac insects, are injurious. The secretion of a white, or bluish, waxy, or farinose substance from the surface of the body is as characteristic of this section as the nauseous odor is of the first. It forms three natural divisions, arranged according to the number of joints to the tarsi--namely TRIMERA, with three joints; DIMERA, with two joints; and MONOMERA, with one joint to the tarsi."

Suborder THYSANOPTERA ([Greek: thysanos], a fringe; [Greek: pteron], wing): This suborder contains the single family _Thripidae_, which comprises minute insects commonly known as Thrips, and of which a common species, _Thrips striatus_, is shown in the accompanying figure. (See Fig. 22.) They bear strong relations to both the Pseudoneuroptera and the Hemiptera and by later writers are generally associated with the latter order. They feed on plants, puncturing and killing the leaves, or on other plant-feeding species of their own class, and are characterized by having narrow wings crossed on the back when at rest, and beautifully fringed, from which latter feature the name of the suborder is derived.

The mouth parts are peculiar in that they are intermediate in form between the sucking beak of Hemiptera and the biting mouth parts of other insects.

Their eggs resemble those of Hemiptera; the larvae and pupae are active, and in form resemble the adult, except in the absence of wings. Some species, also, are wingless in the adult stage.

The pupae are somewhat sluggish and the limbs and wings are enclosed in a thin membrane which is expanded about the feet into bulbous enlargements, giving rise to the name "bladder-footed" (Physopoda) applied to these insects by Burmeister.

"Order DIPTERA ([Greek: dis], twice; [Greek: pteron], wing) or Two-winged Flies. The only order having but two wings, the hind pair replaced by a pair of small, slender filaments clubbed at tip, and called halteres, poisers, or balancers.

"No order surpasses this in the number of species or in the immense swarms of individuals belonging to the same species which are frequently met with. The wings, which are variously veined, though appearing naked to the unaided eye, are often thickly covered with very minute hairs or hooks. As an order the Diptera are decidedly injurious to man, whether we consider the annoyances to ourselves or our animals of the Mosquito, Buffalo-gnat, Gad-fly, Breeze-fly, Zimb or Stomoxys, or the injury to our crops of the Hessian-fly, Wheat-midge, Cabbage-maggot, Onion-maggot, etc. There are, in fact, but two families, Syrphidae and Tachinidae, which can be looked upon as beneficial to the cultivator, though many act the part of scavengers. No insects, not even the Lepidoptera, furnish such a variety of curious larval characters, and none, perhaps, offer a wider or more interesting field of investigation to the biologist. It is difficult to give any very satisfactory arrangement of these Two-winged flies, though they easily fall into two rather artificial sections. These are: 1st, NEMOCERA, or those with long antennae, having more than six joints, and palpi having four or five joints. The pupa is naked, as in the Lepidoptera, with the limbs exposed. This kind of pupa is called _obtected_. 2d, BRACHOCERA, or those with short antennae, not having more than three distinct joints, and palpi with one or two joints. The pupa is mostly _coarctate_, _i. e._, is formed within, and more or less completely connected with, the hardened and shrunken skin of the larva.

strus ovis_). 1, 2, flies; 3, puparium; 4, 5, and 6, larvae or bots.]

"The most anomalous of the Diptera are the Forest-flies and Sheep-ticks (_Hippoboscidae_). They have a horny and flattened body, and resemble lice in their parasitic habits, living beneath the hair of bats and birds. Their mode of development has always attracted the attention of entomologists. The larvae are hatched in the abdomen of the female, which is capable of distention. There it remains and, after assuming the pupa state, is deposited in the form of a short, white, egg-like object, without trace of articulation, and nearly as large as the abdomen of the female fly. Closely allied to these are the Bat-ticks (_Nycteribidae_), which possess neither wings nor balancers, and remind one strongly of spiders.

"In this order we may also place certain wingless lice (such as _Braula c[oe]ca_, Nitzch), which infests the Honey-bee in Europe, northern Africa, and western Asia, but which has not yet been detected in this country.

"Suborder APHANIPTERA ([Greek: aphanes], inconspicuous; [Greek: pteron], wing) or Fleas, comprising the single family Pulicidae, now placed with the Diptera. Everybody is supposed to be familiar with the appearance of the Flea--its bloodthirsty propensities and amazing muscular power; and while everyone may not have the leisure and means to experience the exhilarating influence of the chase after larger animals, there is no one--be he never so humble--who may not indulge in the hunt after this smaller game! In place of wings the flea has four small, scaly plates. The minute eggs--about a dozen to each female--are laid in obscure places, such as the cracks of a floor, the hair of rugs, etc., and the larva is worm-like and feeds upon whatever animal matter--as grease and blood--or decaying vegetable matter it can find.

"Order ORTHOPTERA ([Greek: orthos], straight; [Greek: pteron], wing), or Straight-winged Insects. Characterized by having the front wings (called _tegmina_) straight and usually narrow, pergameneous or parchment-like, thickly veined, and overlapping at tips when closed; the hind wings large and folding longitudinally like a fan. Transformations incomplete.

"The insects of this order have a lengthened body and very robust jaws, with a correspondingly large head. The legs are strong, and fashioned either for grasping, running, climbing, jumping, or burrowing. As in the other orders, where the transformations are incomplete, the young differ little from the parent, except in the want of wings; and in many instances even this difference does not exist, as there are numerous species which never acquire wings. There are no aquatic Orthoptera. Some are omnivorous, others carnivorous, but most of them herbivorous. They form four distinct sections: 1st, CURSORIA, Cockroaches; 2d, RAPTATORIA, Mantes; 3d, AMBULATORIA, Walking-sticks; 4th, SALTATORIA, Crickets, Grasshoppers, and Locusts.

"Suborder DERMAPTERA[2] ([Greek: derma], skin; [Greek: pteron], wing), or Earwigs, consisting of the single family Forficulidae, which may be placed with the Orthoptera. They are rare insects with us, but very common in Europe, where there prevails a superstition that they get into the ear and cause all sorts of trouble. The front wings are small and leathery; the hind ones have the form of a quadrant, and look like a fan when opened; and the characteristic feature is a pair of forceps-like appendages at the end of the body, best developed in the males. They are nocturnal in habit, hiding during the day in any available recess. The female lays her eggs in the ground, and singularly enough, broods over them and over her young, the latter crowding under her like chicks under a hen."

[2] Euplexoptera of some authors from [Greek: eu], well;
[Greek: plecho], folded, referring to the folded wings.

"Order NEUROPTERA ([Greek: neuron], nerve; [Greek: pteron], wing), or Nerve-winged insects. Characterized by having the wings reticulate with numerous veins so as to look like net-work. The order forms two natural divisions, the first including all those which undergo a complete, and the second, called Pseudo-neuroptera (Dictyotoptera, Burmeister), those which undergo an incomplete metamorphosis. * * * The insects of this order are, as a whole, more lowly organized, and more generally aquatic, than either of the others. A natural arrangement of them is difficult on account of their degradational character. They present forms which are synthetic and closely approach the other orders, and the evolutionist naturally looks upon them as furnishing an idea of what the archetypal forms of our present insects may have been. They are, as a rule, large and sluggish, with the body parts soft and little specialized, and the muscles weak. Their remains are found in the Devonian and Carboniferous deposits.

"They are mostly carnivorous, and with the exception of the White-ants and certain Book-lice they none of them affect man injuriously, while some are quite beneficial."

The first division of this order, or the Neuroptera proper, characterized by having incomplete metamorphoses, may be considered under the three following suborders:

"Suborder TRICHOPTERA ([Greek: thrix], hair; [Greek: pteron], wing), or Caddis-flies, containing the single family Phryganeidae, and placed with the Neuroptera, though bearing great affinities with the Lepidoptera. Every good disciple of Walton and lover of the "gentle art" knows the value of the Caddis-fly, or Water-moth, as bait. These flies very much resemble certain small moths, the scales on the wings of the latter being replaced in the former with simple hairs. The larvae live in the water and inhabit silken cases, which are usually cylindrical and covered with various substances, according to the species, or the material most conveniently obtained by the individual."

Suborder MECOPTERA ([Greek: mekos], length; [Greek: pteron], wing). This suborder includes a peculiar group of insects, the most striking characteristics of which are the mouth-parts, which are prolonged into a rostrum or beak. The wings are long and narrow, and of nearly equal size. The abdomen of the male is constricted near its posterior end and terminates in long clasping organs from which these insects obtain the common name of Scorpion-flies.

The larvae of one genus (_Panorpa_) are remarkable for their great resemblance to the larvae of Lepidoptera. They have, however, eight pairs of abdominal legs. The habits of these insects are not well known, but they are supposed to be generally.

Suborder NEUROPTERA. This group as restricted by modern authors is a small one, including the largest species, as in the Hellgrammite, the Lace-wing Flies, the Ant-lions, and the Mantispas representing the families, Sialidae and Hemerobiidae, with their subfamilies. The first includes the so-called Hellgrammite Fly (_Corydalus cornutus_), one of our largest and most striking insects, the larvae of which is known as Dobsons by anglers, and is aquatic and carnivorous in habit. The Hemerobiidae is a large family, comprising, as a rule, delicate insects with rather ample gauzy wings. The larvae are predaceous. The common Lace-wing flies are among our most beneficial insects, destroying plant-lice and other soft-bodied species. To the same family belongs the Ant-lion (_Myrmeleon_), the larvae of which have the curious habit of constructing a funnel-shaped burrow in the sand, in the bottom of which they conceal themselves and wait for any soft-bodied insects which may fall into the trap. This family also includes the peculiar Mantis-like insects belonging to the genus _Mantispa_. As in the true Mantis, the prothorax of these insects is greatly elongated and the first pair of legs are fitted for grasping. The larvae are parasitic in the egg-sacs of certain large spiders (genera _Licosa_, _Dolomedes_, etc.), and undergo a remarkable change in form after the first molt. In the first stage the larvae are very agile, with slender bodies and long legs. After molting the body becomes much swollen and the legs are much shortened, as are also the antennae, the head becoming small and the general appearance reminding one of the larva of a bee.

The second section of the Neuroptera, characterized by complete metamorphosis, comprises the following suborders:

Suborder PLATYPTERA ([Greek: platys], flat; [Greek: pteron], wing). Under this head are grouped the White-ants (_Termitidae_), the Bird-lice (_Mallophaga_), and the Book-mites (_Psocidae_). The suborder receives its name from the fact that in the case of the winged forms the wings, when at rest, are usually laid flat upon the back of the insect. The Mallophaga, or Bird-lice, are degraded wingless insects, and are parasitic chiefly on birds, but also on mammals. In shape of body and character of the mouth-parts they are most nearly allied to the Psocidae. The latter family includes both winged and wingless forms, the Book-mites belonging to the latter category. The winged forms may be illustrated by the common species, _Psocus venosus_ (see Fig. 40). The legs and antennae are long and slender and the wings are folded roof-like over the body when the insect is at rest. They feed on lichens and dry vegetation.

The Termitidae are represented in this country by the White-ant (_Termes flavipes_), which is frequently so destructive to woodwork, books, etc. The term White-ant applied to these insects is unfortunate, as in structure they are widely separated from ants and resemble them only in general appearance and also in their social habits. Like the ants they live in colonies and have a number of distinct forms, as winged and wingless, males and females, and workers and soldiers.

Suborder PLECOPTERA ([Greek: plektos], plaited; [Greek: pteron], wing). Closely allied to the latter suborder is the suborder Plecoptera, which includes the single family Perlidae or Stone-flies. The larvae and pupae of these insects are aquatic, being often found under stones in water, whence the name. The adults are long, flattened insects, with long antennae. The wings are ample and are somewhat folded or plaited, from which character the suborder takes its name.

Suborder ODONATA ([Greek: othous], tooth). This includes the Dragon-flies or Libellulidae, the most common and the best known of the Neuroptera. The larva and the active pupa or nymph are aquatic and are predaceous, as is also the adult. A common species is represented at Fig. 33.

The Suborder EPHEMEROPTERA ([Greek: ephemeron], a day-fly; [Greek: pteron], wing) comprises the May-flies, or Ephemeridae (see Fig. 42). These insects are very fragile and are often attracted in enormous numbers to electric lights. They have large front wings, while the hind wings are small, rudimentary, or wanting. They are furnished with two or three very long, jointed, threadlike caudal appendages. The larval and nymphal stages are passed in the water and aquatic vegetation furnishes the food, although some species may be predaceous. The adults have very rudimentary mouths and eat nothing; their term of life is also very limited, not exceeding 2-4 days.

Suborder THYSANURA ([Greek: thysanos], tassel; [Greek: oura], tail). This suborder comprises minute, degraded insects commonly known as Spring-tails, Bristle-tails, Fish-moths, Snow-fleas, etc. They occur in damp situations and also infest books, wall-paper, etc., eating the starch paste in the book-bindings, or beneath the wall paper. They comprise very primitive forms and are interesting because they are supposed to represent the original stock from which the higher orders of insects have sprung. They are wingless, usually with simple eyes, and clothed with scales, and undergo no metamorphosis. Some of them, as the Fish-moth (_Lepisma sp._), run very rapidly and are furnished at the end of the body with a number of long bristles. In other forms these anal bristles or stylets are united at the base and bent under the body and become a powerful jumping organ, giving them the very appropriate name of Spring-tails.

COLLECTING.

GENERAL CONSIDERATIONS.--"Few departments of natural history offer greater inducements or facilities to the student than Entomology. He need not pass his threshold for material, for it may be found on every hand and at all seasons. The directions for collecting, preserving, and studying insects might be extended indefinitely in detail, as volumes have already been written on the subject; but the more general and important instructions are soon given.

"Beginners are very apt to supply themselves with all sorts of appliances advertised by natural history furnishing stores. Many of these appliances, when it comes to real, practical field-work, are soon abandoned as useless incumbrances; and the greater the experience, the simpler will be the paraphernalia. My own equipment, on a collecting trip, consists chiefly of a cotton umbrella, a strong and narrow steel trowel or digger, a haversack slung across the shoulders, a cigar box lined with sheet cork, and a small knapsack attached to a waistbelt which girts a coat, not of many colors, but of many pockets, so made that in stooping nothing falls out of them. The umbrella is one of the indispensables. It shields, when necessary, from old Sol's scorching rays and from the pelting, drenching storm; brings within reach, by its hooked handle, many a larva-freighted bough which would otherwise remain undisturbed; and forms an excellent receptacle for all insects that may be dislodged from bush or branch. Opened and held inverted under a bough with the left hand, while the right manipulates a beating-stick, cut for the occasion, it will be the recipient of many a choice specimen that would never have been espied amid its protective surroundings. Some collectors use an umbrella painted or lined on the inside with white, to facilitate the detection of any object that drops into it; but as there are fully as many, if not more, pale and white insects as there are dark or black ones, the common dark umbrella is good enough for all ordinary purposes; and if any improvement on the ordinary cotton umbrella is desired, it should be in the way of a joint or knuckle about the middle of the handle, which will facilitate its packing and using. The trowel is valuable for prying off the loosened bark from old trees, whether felled or standing, and for digging into the ground or into decaying stumps and logs. The haversack is for the carriage of different kinds of boxes (those made of tin being best) intended for larval and other forms which it is necessary to bring home alive for breeding purposes; and if made with a partition so that the filled and empty boxes may be separated, all the better; it may also be used for nets and other apparatus to be mentioned, and for such provender as is necessary on the trip. The knapsack may be made on the plan of a cartridge box, of stout canvas or leather, and should be of moderate size and slung onto the belt so as to be slipped to any part of the waist and not hinder free bodily motion. It may be used to carry bottles, phials, and other small appliances, and should be accordingly partitioned and furnished with loops or pockets on the inside. The cigar-box is for the reception of pinned specimens, and may be slipped onto the belt, or buttoned to the trousers by means of leather.

"The greatest requisites in collecting are a pair of sharp eyes and ready hands, with coolness and self-possession; but a few traps will materially aid. One of the most important is the hand-net, which may be made so as to subserve the two purposes of a sweeping and an air-net."

"The frame of the net which I use is illustrated herewith (Fig. 44), and will be found strong and serviceable and conveniently portable. It is constructed as follows: Take two pieces of stout brass wire, each about 20 inches long; bend them half-circularly and at one end by a folding hinge having a check on one side, _b_. The other ends are bent and beaten into two square sockets, _f_, which fit to a nut sunk and soldered into one end of a brass tube, _d_. When so fitted, they are secured by a large-headed screw, _e_, threaded to fit into the nut-socket, and with a groove wide enough to receive the back of a common pocket-knife blade. The wire hoop is easily detached and folded, as at _c_, for convenient carriage; and the handle may be made of any desired length by cutting a stick and fitting it into the hollow tube _a_, which should be about 6 inches long. It is well to have two separate hoops, one of lighter wire, furnished with silk gauze or some other light material, for catching flying insects, and one which is stouter and furnished with a net of stronger material for sweeping non-flying specimens.

"Another still more simple, but less convenient frame, is thus described by my friend F. G. Sanborn, of Boston, Mass.:

'Make a loop of strong iron or brass wire, of about 3-16ths of an inch in thickness, so that the diameter of the loop or circle will not exceed 12 inches, leaving an inch to an inch and a half of wire at each end bent at nearly right angles. Bind the two extremities of the wire together with smaller wire (Fig. 45, _a_), and tin them by applying a drop of muriate of zinc, then holding it in the fire or over a gas flame until nearly red hot, when a few grains of block tin or soft solder placed upon them will flow evenly over the whole surface and join them firmly together. Take a Maynard rifle cartridge tube, or other brass tube of similar dimensions; if the former, file off the closed end or perforate it for the admission of the wire, and having tinned it in the same manner on the inside, push a tight-fitting cork half way through (Fig. 45, _c_) and pour into it melted tin or soft solder, and insert the wires; if carefully done, you will have a firmly constructed and very durable foundation for a collecting net. The cork being extracted will leave a convenient socket for inserting a stick or walking cane to serve as a handle.'

"My friend, J. A. Lintner, of Albany, N. Y., makes very good use, in his ordinary promenades, of a telescopic fish-rod, with a head (Fig. 46) screwed on to one end, in which to fasten an elastic brass coil on which the net is drawn, but which when not in use sits snugly inside his silk hat.