Chapter VIII: Hemiptera, or Bugs—anoplura 532 (17)

The early stages of these Insects are of great interest. The eggs, so far as known, are peculiar flat oval scales, of irregular outline and transparent; we have figured an example in Vol. V. Fig. 83. The eggs of the same moth are said to vary much in size, though the larvae that emerge from them differ little from one another in this respect. The latter are peculiar, inasmuch as they have no abdominal feet, and the thoracic legs are but small; hence the caterpillars move in an imperceptible gliding manner that has suggested for some of them the name of slug-worms. The metamorphoses of a few are known. They may be arranged in two groups; one in which the larva is spinose or armed with a series of projections and appendages persisting throughout life; while in the members of the second group the spines have only a temporary existence. At the moment the young larva of _Apoda testudo_ emerges from the egg it has no conspicuous spines or processes, and is an extremely soft, colourless creature,[290] but it almost immediately displays a remarkable system of complex spines. These really exist in the larva when it is hatched, and are thrust out from pits, as explained by Dr. Chapman. In the succeeding stages, the spines become modified in form, and the colour of the body and the nature of {403}the integument are much changed, so that in the adult larva (Fig. 199) the spines have subsided into the condition of mere prominences, different in colour from the rest of the surface. These larvae appear to be destitute of a head, but there really exists a large one which is retracted, except during feeding, into the body; the five pairs of abdominal feet of the larvae of allied families are replaced by sucker-like structures on the first eight abdominal segments. The spinneret of the mouth is not a pointed tubular organ, but is fish-tailed in shape, and hence disposes the silky matter, that aids the larva in moving on the leaves, in the form of a ribbon instead of that of a thread. It has been stated that these peculiar larvae "imitate" the coloured galls frequently found on the leaves of trees. The North American forms of this family have very varied and most extraordinary larvae.[291] In the pretty and conspicuous larva of _Empretia stimulea_, the tubercles or processes of the body are, in the later stages, armed with hairs, that contain a poisonous or irritating fluid, said to be secreted by glands at the bases of the processes. These hairs are readily detached and enter the skin of persons handling the caterpillars. The larva of the North American Hag-moth, _Phobetron pithecium_, is a curious object, bearing long, fleshy appendages covered with down. Hubbard makes the following statement as to the instincts of this larva:[292]—"The hag-moth larvae do not seek to hide away their cocoons, but attach them to leaves and twigs fully exposed to view, with, however, such artful management as to surroundings and harmonising colours that they are of all the group the most difficult to discover. A device to which this Insect frequently resorts exhibits the extreme of instinctive sagacity. If the caterpillar cannot find at hand a suitable place in which to weave its cocoon, it frequently makes for itself more satisfactory surroundings by killing the leaves, upon which, after they have become dry and brown in colour, it places its cocoon. Several of these caterpillars unite together, and selecting a long and vigorous immature shoot or leader of the orange tree, they kill it by cutting into its base until it wilts and bends over. The leaves of a young shoot in drying turn a light tan-color, which {404}harmonises most perfectly with the hairy locks of the caterpillar covering the cocoon. The latter is, consequently, not easily detected, even when placed upon the exposed and upturned surface of the leaf."

The cocoons of Limacodidae are unusually elaborate, the larva forming a perfect lid in order to permit itself to escape when a moth. Chapman states that the larva lies unchanged in the cocoon all winter, moulting to a pupa in the spring, and that the pupa escapes from the cocoon previous to the emergence of the moth.[293] Both Chapman and Packard look on the family as really nearer to Microlepidoptera than to Bombyces; Meyrick (calling it Heterogeneidae) places it at the end of his series Psychina next Zygaenidae.

We may allude here to the little moths, described by Westwood under the name of _Epipyrops_,[294] that have the extraordinary habit of living on the bodies of live Homopterous Insects of the family Fulgoridae in India. What their nutriment may be is not known. The larva exudes a white flocculent matter, which becomes a considerable mass, in the midst of which the caterpillar changes to a pupa. Westwood placed the Insect in Arctiidae; Sir George Hampson suggests it may be a Limacodid, and this appears probable.

FAM. 27. MEGALOPYGIDAE (or LAGOIDAE).—The American genera, _Megalopyge_ and _Lagoa_, are treated by Berg and by Packard[295] as a distinct family intermediate between Saturniidae and Limacodidae. The larva is said by the latter authority to have seven pairs of abdominal feet instead of five pairs—the usual number in Lepidoptera. When young the caterpillars of _Lagoa opercularis_ are white and resemble a flock of cotton wool. When full grown the larva presents the singular appearance of a lock of hair, moving in a gliding, slug-like manner. Under the long silky hair there are short, stiff, poison-hairs. The larva forms a cocoon, fitted with a hinged trap-door for the escape of the future moth. This curious larva is destroyed by both Dipterous and Hymenopterous parasites.

FAM. 28. THYRIDIDAE.—A small family of Pyraloid moths, exhibiting considerable variety of form and colour, frequently with hyaline patches on the wings. They are mostly small {405}Insects, and contain no very striking forms. Some of them look like Geometrids of various groups. The family is widely distributed in the tropical zone, and includes 25 genera, of which _Rhodoneura_, with upwards of 100 species, is the chief one. The larvae are said to be similar to those of Pyralidae. This family is considered by Hampson and Meyrick to be ancestral to butterflies.[296]

FAM. 29. LASIOCAMPIDAE (_Eggers_, _Lappet-moths_). Usually large Insects densely covered with scales, without frenulum, but with the costal area of the hind wing largely developed, and the male antennae beautifully pectinate, Lasiocampids are easily recognised. They are well known in Britain, though we have but few species. The flight of some of the species is powerful, but ill-directed, and the males especially, dash about as if their flight were quite undirected; as indeed it probably is. The difference in the flight of the two sexes is great in some species. In the genus _Suana_ and its allies we meet with moths in which the difference in size of the two sexes is extreme; the males may be but 1½ inches across the wings, while the very heavy females may have three times as great an expanse. Kirby separates these Insects to form the family Pinaridae; it includes the Madagascar silkworm, _Borocera madagascariensis_. The African genus _Hilbrides_ is remarkable for the wings being destitute of scales, and consequently transparent, and for being of very slender form like a butterfly. The eggs of Lasiocampidae are smooth, in certain cases spotted in an irregular manner like birds' eggs. Sometimes the parent covers them with hair. The larvae are clothed with a soft, woolly hair, as well as with a shorter and stiffer kind, neither beautifully arranged nor highly coloured, and thus differing from the caterpillars of Lymantriidae; this hair in some cases has very irritating properties. Cocoons of a close and compact nature are formed, and hairs from the body are frequently mixed with the cocoon. In {406}some species the walls of the cocoons have a firm appearance, looking very like egg-shell—a fact which is supposed to have given rise to the name of Eggers. Professors Poulton and Meldola have informed us that this appearance is produced by spreading calcium oxalate on a slight framework of silk, the substance in question being a product of the Malpighian tubes.[297] In various families of Lepidoptera it happens that occasionally the pupa exists longer than usual before the appearance of the perfect Insect, and in certain members of this family—notoriously in _Poecilocampa populi_, the December moth—this interval may be prolonged for several years. There is not at present any explanation of this fact. It may be of interest to mention the following case:—From a batch of about 100 eggs deposited by one moth, in the year 1891 (the Puss-Moth of the family Notodontidae), some sixty or seventy cocoons were obtained, the feeding up of all the larvae having been effected within fourteen days of one another; fourteen of the Insects emerged as moths in 1892; about the same number in 1893; in 1894, twenty-five; and in 1895, eleven emerged. Lasiocampidae is a large family, consisting of some 100 genera and 500 or more species, and is widely distributed. It is unfortunately styled Bombycidae by some naturalists.

FAM. 30. ENDROMIDAE.—The "Kentish glory," _Endromis versicolor_, forms this family; it is a large and strong moth, and flies wildly in the daytime in birch-woods. The larva has but few hairs, and is said when young to assume a peculiar position, similar to that of saw-fly larvae, by bending the head and thorax backwards over the rest of the body.

FAM. 31. PTEROTHYSANIDAE.—Consists of the curious East Indian genus _Pterothysanus_, in which the inner margins of the hind wings are fringed with long hairs. They are moths of slender build, with large wing-expanse, black and white in colour, like Geometrids. There is no frenulum. Metamorphoses unknown.

FAM. 32. LYMANTRIIDAE.—(Better known as LIPARIDAE). These are mostly small or moderate-sized moths, without brilliant colours; white, black, grey and brown being predominant; with highly-developed, pectinated antennae in the male. The larva is very hairy, and usually bears tufts or brushes of shorter hairs, {407}together with others much longer and softer, these being sometimes also amalgamated to form pencils; the coloration of these larvae is in many cases very conspicuous, the tufts and pencils being of vivid and strongly contrasted colours. Some of these hairy larvae are poisonous. A cocoon, in which much hair is mixed, is formed. The pupae are remarkable, inasmuch as they too are frequently hairy, a very unusual condition in Lepidoptera. The Lymantriidae is one of the largest families of the old group Bombyces; it includes some 180 genera and 800 species, and is largely represented in Australia. _Dasychira rossii_ is found in the Arctic regions. In Britain we have eight genera represented by eleven species; the Gold-tails, Brown-tails and Vapourer-moths being our commonest Bombyces, and the latter being specially fond of the London squares and gardens, where its beautiful larva may be observed on the leaves of roses. Most of the Lymantriidae are nocturnal, but the male Vapourer-moth flies in the daytime. In this family there are various species whose females have the wings small and unfit for flight, the Insects being very sluggish, and their bodies very heavy. This is the state of the female of the Vapourer-moth. The males in these cases are generally remarkably active, and very rapid on the wing.

Some of these moths increase in numbers to an enormous extent, and commit great ravages. _Psilura monacha_—the Nun, "die Nonne" of the Germans,[298]—is one of the principal troubles of the conservators of forests in Germany, and great sums of money are expended in combating it; all sorts of means for repressing it, including its infection by fungi, have been tried in vain. The caterpillars are, however, very subject to a fungoid disease, communicated by natural means. It is believed, too, that its continuance in any locality is checked after a time by a change in the ratio of the two sexes. It is not a prolific moth, for it lays only about 100 eggs, but it has been shown that after making allowance for the numerous individuals destroyed by various enemies, the produce of one moth amounts in five generations to between four and five million individuals. The larva feeds on Coniferae, and on many leafy trees and shrubs. The young {408}larva is provided with two sets of setae, one set consisting of very long hairs, the other of setae radiating from warts; each one of this second set of spines has a small bladder in the middle, and it has been suggested that these assist in the dissemination of the young caterpillars by atmospheric means.[299] These aerostatic setae exist only in the young larva. The markings of the moth are very variable; melanism is very common both in the larva and imago; it has been shown conclusively that these variations are not connected, as black larvae do not give a larger proportion of black moths than light-coloured caterpillars do. In England this moth is never injurious. A closely allied form, _Ocneria dispar_, was introduced by an accident into North America from Europe about thirty years ago; for twenty years after its introduction it did no harm, and attracted but little attention; it has, however, now increased so much in certain districts that large sums of money have been expended in attempting its extirpation.

_Dasychira pudibunda_ has occasionally increased locally to an enormous extent, but in the limited forests of Alsace the evil was cured by the fact that the caterpillars, having eaten up all the foliage, then died of starvation.[300] _Teara melanosticta_ is said to produce columns of processionary caterpillars in Australia.

FAM. 33. HYPSIDAE (or AGANAIDAE).—A family of comparatively small extent, confined to the tropical and sub-tropical regions of the Eastern hemisphere. The colours are frequently buff and grey, with white streaks on the outer parts of the wings. We have nothing very like them in the European fauna, our species of _Spilosoma_ are perhaps the nearest approach. In _Euplocia_ the male has a pouch that can be unfolded in front of the costa at the base of the anterior wing; it is filled with very long, peculiar, hair-like scales growing from the costal margin; both sexes have on each side of the second abdominal segment a small, projecting structure that may be a sense-organ. The female is more gaily coloured than the male.

FAM. 34. ARCTIIDAE.—With the addition recently made to it of the formerly separate family Lithosiidae, Arctiidae has become the most extensive family of the old Bombycid series of moths, comprising something like 500 genera and 3000 species. Hampson recognises four sub-families—Arctiinae, Lithosiinae, {409}Nolinae, Nycteolinae,—to which may be added others from America—Pericopinae, Dioptinae, Ctenuchinae; these sub-families being treated as families by various authors. The sub-family Arctiinae includes our Tiger- and Ermine-moths, and a great many exotic forms of very diverse colours and patterns; the species of this division are, on the whole, probably more variable in colour and markings than in any other group of Lepidoptera. There are many cases of great difference of the sexes; in the South American genus _Ambryllis_ the male is remarkable for its hyaline wings with a few spots; while the female is densely scaled, and very variegate in colour. There are some cases (the South European genus _Ocnogyna_) where the female is wingless and moves but little, while the male flies with great rapidity. _Epicausis smithi_, from Madagascar, one of the most remarkable of moths, is placed in this division of Arctiidae; it is of a tawny colour, variegate with black; the abdomen of this latter colour is terminated by a large tuft of long scarlet hairs; the Insect has somewhat the appearance of a Hummingbird-hawkmoth. _Ecpantheria_ is an extensive genus of tropical American moths (having one or two species in North America), of black and white or grey colours, with very complex markings; the male in some species has a part of the hind wing produced as a tail, or lobe, of a different colour.

The sub-family Pericopinae are almost peculiar to South America (two species of _Gnophaela_ exist in North America); some of this sub-family bear a great resemblance to Heliconiid butterflies.

The Dioptinae are likewise American moths of diurnal habits, and many of them bear a striking resemblance to the Ithomiid butterflies they associate with when alive.

The sub-family Lithosiinae is of great extent; our native "Footmen" give a very good idea of it; the moths are generally of light structure, with long, narrow front wings; a simple system of yellow and black colour is of frequent occurrence. Many of this group feed in the larval state on lichens. Hampson includes in this group the Nyctemeridae—light-bodied diurnal moths, almost exclusively of black and white colours, of Geometrid form, frequently treated as a distinct family.

The sub-family Nolinae is a small group of rather insignificant Insects, in appearance like Pyralids or Geometrids; four or five {410}species are native in Britain. Packard maintains the family Nolidae as distinct.[301]

The sub-family Nycteolinae consists of a few small moths the position of which has always been uncertain; _Nycteola_ (better known as _Sarrothripus_), _Halias_, and _Earias_ are all British genera that have been placed amongst Tortrices, to which they bear a considerable resemblance. _Sarrothripus_ is at present placed by Hampson in Noctuidae, by others in Lithosiidae, by Meyrick in Arctiidae. The sub-family forms the family Cymbidae of Kirby;[302] it includes at present only about 70 species, all belonging to the Eastern hemisphere. Two types of larvae are known in it: one bare, living exposed on leaves; the other, _Earias_, hairy, living among rolled-up leaves. _Halias prasinana_ is known from the testimony of numerous auditors to produce a sound when on the wing, but the _modus operandi_ has not been satisfactorily ascertained. Sound-production seems to be of more frequent occurrence in Arctiidae than it is in any other family of Lepidoptera; _Dionychopus niveus_ produces a sound by, it is believed, friction of the wings. In the case of the genera _Setina_ and _Chelonia_ the process is said to be peculiar to the male sex: Laboulbène believes it to proceed from drum-like vesicles situate one on each side of the base of the metathorax.[303]

FAM. 35. AGARISTIDAE.—An interesting assemblage of moths, many of them diurnal and of vivid colours, others crepuscular. There is considerable variety of appearance in the family, although it is but a small one, and many of its members remind one of other and widely separated families of Lepidoptera. The style and colour of the Japanese _Eusemia villicoides_ are remarkably like our _Arctia villica_. In some forms the antennae are somewhat thickened towards the tip and hooked, like those of the Skipper butterflies. The family consists at present of about 250 species, but we doubt its being a sufficiently natural one. It is very widely distributed, with the exception that it is quite absent from Europe and the neighbourhood of the Mediterranean Sea. In North America it is well represented. The larvae, so far as known, are not very remarkable; they have some lateral tufts of hair, as well as longer hairs scattered over the body.

{411}The male of the Indian _Aegocera tripartita_ has been noticed to produce a clicking sound when flying, and Sir G. Hampson has shown[304] that there is a peculiar structure on the anterior wing; he considers that this is rubbed against some spines on the front feet, and that the sound is produced by the friction. Though this structure is wanting in the acknowledged congeners of _A. tripartita_, yet it occurs in a very similar form in the genus _Hecatesia_, already noticed under Castniidae.

FAM. 36. GEOMETRIDAE (_Carpets_, _Pugs_, _etc._)—This very extensive family consists of fragile moths, only a small number being moderately stout forms; they have a large wing-area; the antennae are frequently highly developed in the males, but on this point there is much diversity. Either the frenulum or the proboscis is absent in a few cases. The caterpillars are elongate and slender, with only one pair of abdominal feet—placed on the ninth segment—in addition to the anal pair, or claspers. They progress by moving these two pairs of feet up to the thoracic legs, so that the body is thrown into a large loop, and they are hence called Loopers or Geometers. The family is universally distributed, and occurs even in remote islands and high latitudes; in Britain we have about 270 species. The family was formerly considered to be closely connected with Noctuidae, but at present the opinion that it has more intimate relations with the families we have previously considered is prevalent. Packard considers it near to Lithosiidae, while Meyrick merely places the six families, of which he treats it as composed, in his series Notodontina. Hampson adopts Meyrick's six families as subfamilies, but gives them different names, being in this respect more conservative than Meyrick, whose recent revision of the European forms resulted in drastic changes in nomenclature.[305] This classification is based almost exclusively on wing-nervuration. The number of larval legs and the consequent mode of walking is one of the most constant characters of the group; the few exceptions that have been detected are therefore of interest. _Anisopteryx aescularia_ has a pair of undeveloped feet on the eighth segment, and, according to Meyrick, its allies "sometimes show rudiments of the other two pairs." The larva of _Himera {412}pennaria_ is said to have in early life a pair of imperfect feet on the eighth segment, which disappear as the larva approaches maturity.

The position of the abdominal feet and claspers throws the holding power of the larva to the posterior part of the body, instead of to the middle, as in other caterpillars. This, combined with the elongate form, causes these larvae when reposing to assume attitudes more or less different from those of other larvae; holding on by the claspers, some of these Insects allow all the anterior parts of the body to project in a twig-like manner. The front parts are not, however, really free in such cases, but are supported by a thread of silk extending from the mouth to some point near-by. Another plan adopted is to prop the front part of the body against a twig placed at right angles to the supporting leaf, so that the caterpillar is in a diagonal line between the two (Fig. 202). Other Geometers assume peculiar coiled or spiral attitudes during a whole or a portion of their lives; some doing this on a supporting object—leaf or twig—while others hang down (_Ephyra pendularia_). Certain of the larvae of Geometridae vary in colour, from shades of brown to green; there is much diversity in this variation. In some species it is simple variation; in others it is dimorphism, _i.e._ the larvae are either brown or green. In other cases the larvae are at first variable, subsequently dimorphic. In _Amphidasis betularia_ it would appear that when the larva is hatched the dimorphism is potential, and that the future colour, whether {413}green or brown, is settled by some determining condition during the first period of larval life and cannot be subsequently modified.[306] According to Poulton, the dark tint is due in _A. betularia_ to colouring matter in the skin or immediately below it, and the green tint to a layer of fat between the hypodermis and the superficial muscles; this layer being always green, but more brightly green in the larvae that are of this colour externally. Much discussion has occurred about these larval attitudes and colours, and it seems probable that Professor Poulton has overrated the value of protection from birds, mammals and entomologists; the chief destroying agents being other than these, and not liable to be thus deceived, even if the vertebrates are. In some cases such resemblance as undoubtedly exists is not made the best use of. The larva shown in figure 202 bore a wonderful resemblance, when examined, to the rose-twigs it lived on, but the effect of this as a concealing agent was entirely destroyed by the attitude; for this, being on different lines to those of the plant, attracted the eye at once. This larva, and we may add numerous other larvae, could have been perfectly concealed by adopting a different attitude, but never did so; the position represented being constantly maintained except while feeding.

In some species of this family the adult females are without wings, or have them so small that they can be of no use for flight. This curious condition occurs in various and widely-separated groups of the Geometridae; and it would be naturally supposed to have a great effect on the economy of the species exhibiting it, but this is not the case. Some of the flightless females affect the highest trees and, it is believed, ascend to their very summits to oviposit. It has been suggested that they are carried up by the winged males, but this is probably only an exceptional occurrence; while, as they are known to be capable of ascending with rapidity by means of crawling and running, it may be taken for granted that this is the usual method with them. Some of these wingless females have been found in numbers on gas-lamps, and are believed to have been attracted by the light, as is the case with very many of the winged forms.[307] {414}Neither is the geographical distribution limited by this inferior condition of the most important of the organs of locomotion, for _Cheimatobia brumata_ (the Winter-moth) one of the species with flightless female, is a common and widely distributed Insect in Europe and North America.

Although the classification of this family is based almost entirely on wing-nervuration, yet there are some divisions of the Geometridae in which this character is remarkably variable, certain individuals frequently exhibiting considerable abnormality.[308] _Amphidasis betularia_ is believed to have changed its variation considerably in the course of the last fifty years. Previous to that time a black variety of the species was unknown, but it has now become common; and it is believed that other species of Geometridae are in process of exhibiting a similar phenomenon.[309]

FAM. 37. NOCTUIDAE (_Owlet-Moths_, _Eulen_ of the Germans).—This very extensive assemblage consists of moths rarely seen in the day-time, of generally sombre colours, with antennae destitute of remarkable developments in the male (except in a small number of forms); proboscis and frenulum both present; a complex sense-organ on each side of the body at the junction of the metathorax and abdomen. The number of species already known can scarcely be less than 8000; owing to their large numbers and the great general resemblance of the forms, their classification is a matter of considerable difficulty. Although the peculiar structure at the base of the thorax was long since pointed out, it has never received any thorough investigation. Few other remarkable structures have yet been discovered: the most interesting is perhaps the peculiarity in the hind wings of the males of certain Ommatophorinae recently pointed out by Sir G. F. Hampson[310]: in the genera _Patula_ and _Argiva_ the form of the hind wings is normal in the females, but in the male the anterior one-half of each of these wings is aborted, and the position of the nervures changed; this condition is connected with the development of a glandular patch or fold on the wing, and is remarkable as profoundly affecting a structure which is {415}otherwise so constant that the classification of the family is largely based on it.

The larvae are as a rule destitute of the remarkable adornments of hairs and armatures of spines that are so common in many of the families we have previously considered; they are fond of concealing themselves during the day and coming out at night to feed; many of them pass most of their time at, or beneath, the surface of the ground, finding nourishment in roots or the lower parts of the stems of plants; this is notably the case in the genus _Agrotis_, which is perhaps the most widely distributed of all the genera of moths. Such caterpillars are known as Cut-worms in North America.[311] The great resemblance, _inter se_, of certain of these Cut-worms, much astonished the American naturalist Harris, who found that larvae almost perfectly similar produced very different moths. The majority of Noctuid larvae have the usual number of legs, viz., three pairs of thoracic legs, four pairs of abdominal feet and the terminal claspers. In some divisions of the family there is a departure from this arrangement, and the abdominal feet are reduced to three, or even to two, pairs. One or two larvae are known—e.g. _Euclidia mi_—in which the claspers have not the usual function, but are free terminal appendages. When the abdominal legs are reduced in number (_Plusia_, e.g.) the larvae are said to be Half-loopers, or Semi-loopers, as they assume to some extent the peculiar mode of progression of the Geometrid larvae, which are known as Loopers. In the case of certain larvae, e.g. _Triphaena_, that have the normal number of feet, it has been observed that when first hatched, the one or two anterior pairs of the abdominal set are ill developed, and the larvae do not use them for walking. This is the case with the young larva of our British _Brephos notha_ (Fig. 203). Subsequently, however, this larva undergoes a considerable change, and appears in the form shown in Fig. 204. This interesting larva joins together two or three {416}leaves of aspen and lives between them, an unusual habit for Noctuid larvae. When about to pupate it bores into bark or soft wood to change to a pupa, Fig. 205; the specimen represented closed the hole of entry by placing two separate doors of silk across the burrow, as shown at _d_. The anal armature of this pupa is terminated by a curious transverse process. The systematic position of this interesting Insect is very uncertain: Meyrick and others associate it with the Geometridae.

The larva of _Leucania unipunctata_ is the notorious Army-worm that commits great ravages on grass and corn in North America. This species sometimes increases in numbers to a considerable extent without being observed, owing to the retiring habits of the larvae; when, however, the increase of numbers has been so great that food becomes scarce, or for some other cause—for the scarcity of food is supposed not to be the only reason—the larvae become gregarious, and migrate in enormous swarms: whence its popular name. The Cotton-worm, _Aletia xylinae_ is even more notorious on account of its ravages. Riley states[312] that in bad years the mischief it commits on the cotton crop causes a loss of £6,000,000, and that for a period of fourteen successive years the annual loss averaged about £3,000,000. This caterpillar strips the cotton plants of all but their branches. It is assisted in its work by another highly destructive Noctuid caterpillar, the Boll-worm, or larva of _Heliothis armigera_, which bores into the buds and pods. This {417}latter Insect attacks a great variety of plants, and has a very wide distribution, being found even in England, where happily it is always a rare Insect.

In Britain, as well as in parts of Northern Europe, a Noctuid moth, _Charaeas graminis_, occasionally increases to an enormous extent: its larva is called the Hill-grub and lives on the grass of pastures, frequently doing great damage in hill-lands. The increase of this moth seems to take place after the manner of an epidemic; a considerable number of years may pass during which it is scarcely seen, and it will then appear in unusual numbers in widely separated localities. This moth lays a large number of eggs, and is not completely nocturnal in habits; sometimes it may be seen on the wing in great numbers in the hottest sunshine, and it has been noticed that there is then a great disproportion of the sexes, the females being ten or twenty times as numerous as the males. In Australia, the Bugong moth, _Agrotis spina_, occurs in millions in certain localities in Victoria: this moth hibernates as an imago, and it formerly formed, in this instar, an important article of food with the aborigines. The powers of increase of another Noctuid moth—_Erastria scitula_—are of great value. Its habits have been described by Rouzaud.[313] On the shores of the Mediterranean the larva of this little moth lives on a Scale-Insect—_Lecanium oleae_—that infests the peach; and as the moth may have as many as five generations in a year, it commits laudable havoc with the pest. The larva is of remarkable form, very short and convex, with small head, and only two pairs of abdominal feet. The scale of the _Lecanium_ is of larger size than is usual in that group of Insects, and the young larva of the _Erastria_ buries itself, as soon as hatched, in one of the scales; it destroys successively numerous scales, and after having undergone several moults, it finds itself provided, for the first time, with a spinneret, when, with the aid of its silk, it adds to and adapts a Coccid scale, and thus forms a portable habitation; this it holds on to by means of the pair of anal claspers, which are of unusual form. The case is afterwards subjected to further alteration, so that it may serve as a protection to the creature when it has changed to a pupa. This moth is said to be free from the attacks of parasites, and if this be the case it is probable that its increase is regulated by the fact that {418}when the creature becomes numerous it thus reduces the food supply, so that its own numbers are afterwards in consequence diminished.

One of the most remarkable genera of British Noctuidae is _Acronycta_,[314] the larvae of which exhibit so much diversity that it has been suggested that the genus should be dismembered and its fragments treated as allied to several different divisions of moths. There are many points of interest in connection with the natural history of these _Acronycta_. _A. psi_ and _A. ridens_ are practically indistinguishable as moths, though the larvae are easily separated: the former species is said to be destroyed to an amazing extent by parasites, yet it remains a common Insect. The genus _Apatela_ is very closely allied to _Acronycta_, and Harris says that "_Apatela_ signifies deceptive, and this name was probably given to the genus because the caterpillars appear in the dress of Arctians and Liparians, but produce true owlet-moths or Noctuas."[315] The species of another British genus, _Bryophila_, possess the exceptional habit of feeding on lichens. Some of the American group Erebides are amongst the largest Insects, measuring seven or eight inches across the expanded wings.

The Deltoid moths are frequently treated as a distinct family, Deltoidae, perhaps chiefly because of their resemblance to Pyralidae. At present, however, they are considered to be separated from Noctuidae by no valid characters.

FAM. 38. EPICOPEIIDAE.—The genus _Epicopeia_ consists of only a few moths, but they are amongst the most extraordinary known: at first sight they would be declared without hesitation to be large swallow-tail butterflies, and Hampson states that they "mimic" the Papilios of the _Polyxenus_ group. Very little is known about these extremely rare Insects, but the larva is stated, on the authority of Mr. Dudgeon, to surpass the moths themselves in extravagance; to be covered with long processes of snow-white efflorescence, like wax, exuded from the skin, and to "mimic" a colony of the larva of a Homopterous Insect. Some ten species of this genus are known from Java, India, China, and Japan. In this family there is said to be a rudimentary frenulum, but it is doubtful whether the hairs that have given rise to this definition really justify it.

{419}FAM. 39. URANIIDAE.—A family of small extent, including light-bodied moths with ample wings and thread-like antennae; most of them resemble Geometridae, but a few genera, _Urania_ and _Nyctalemon_, are like Swallow-tail butterflies and have similar habits. The Madagascar moth, _Chrysiridia madagascariensis_ (better known as _Urania rhipheus_), is a most elegant and beautiful Insect, whose only close allies (except an East African congener) are the tropical American species of _Urania_, which were till recently treated as undoubtedly congeneric with the Madagascar moth. The family consists of but six genera and some sixty species. The question of its affinities has given rise to much discussion, but on the whole it would appear that these Insects are least ill-placed near Noctuidae.[316] The larva of the South American genus _Coronidia_ is in general form like a Noctuid larva, and has the normal number of legs; it possesses a few peculiar fleshy processes on the back. A description of the larva of _Chrysiridia madagascariensis_ has been widely spread; but according to Camboué,[317] the account of the metamorphoses, first given by Boisduval, is erroneous. The larva, it appears, resembles in general form that of _Coronidia_, and has sixteen feet; it is, however, armed with long, spatulate black hairs; it changes to a pupa in a cocoon of open network.

In all the species of this family we have examined, we have noticed the existence of a highly peculiar structure that seems hitherto to have escaped observation. On each side of the second abdominal segment there is an ear-like opening (usually {420}much concealed by overlapping scales), giving entrance to a chamber in the body; this chamber extends to the middle line, being separated from its fellow by only a thin partition. At its anterior and lateral part there is a second vesicle-like chamber, formed by a delicate membrane that extends as far forwards as the base of the abdomen. There can be little doubt that this is part of some kind of organ of sense, though it is much larger than is usual with Insect sense-organs.

FAM. 40. EPIPLEMIDAE.—Under this name Hampson has assembled certain Geometroid moths, some of them placed previously in Chalcosiidae, some in Geometridae. They form a varied group, apparently closely allied to Uraniidae, and having a similar peculiar sense-organ; but are distinguished by the presence of a frenulum. The larva seems to be like that of Uraniidae.

FAM. 41. PYRALIDAE.—This division is to be considered rather as a group of families than as a family; it includes a very large number of small or moderate-sized moths of fragile structure, frequently having long legs; antennae simple, only in a few cases pectinate; distinguished from Noctuidae and all the other extensive divisions of moths by the peculiar course of the costal nervure of the hind wing, which either keeps, in the middle of its course, near to the sub-costal or actually unites with it, subsequently again separating. Members of the Pyralidae are found in all lands; in Britain we have about 150 species. The larvae are usually nearly bare, with only short, scattered setae, and little coloration; they have most varied habits, are fond of concealment, and are very lively and abrupt in movement, wriggling backwards as well as forwards, when disturbed; a cocoon is formed for the metamorphosis.

The family as a whole consists of Insects of unattractive appearance, although it contains some very elegant and interesting moths and numerous forms of structural interest. In the genus _Thiridopteryx_ little transparent spaces on the wings occur as a character peculiar to the males; the spaces are correlative with a greater or less derangement of the wing-nervures. In some other forms there is a remarkable retinaculum, consisting of large scales, and this, too, is connected with a distortion of the wing-nervures. The Pyralidae—Pyralites of Ragonot,[318] Pyralidina of {421}Meyrick—have recently been revised by two naturalists of distinction almost simultaneously; unfortunately their results are discrepant, Meyrick including Pterophoridae and Orneodidae, and yet admitting in all only eight families; while Ragonot does not include the two groups named, but defines seventeen tribes of the two families—Pyralidae and Crambidae—that he admits.

The Pyraustidae of Meyrick is an enormous division including the Hydrocampidae and Scopariidae of many authors, as well as the Pyraustinae proper and a small group of Ragonot's, the Homophysinae. The division Scopariinae is believed to be amongst the "most ancient" of Lepidoptera; the food of the larvae consists of moss and lichens. This group is widely distributed, being richly represented in Australia, New Zealand, and the Hawaiian Islands, as well as in Europe; and probably really occurs wherever their food-plants exist accompanied by a tolerable climate. The statistics of the distribution of this group, so far as at present known, have been furnished by Mr. Meyrick, as follows:—European region, about 25 species; Madeira, 3; St. Helena, 6; South Africa, 2 or 3; India, 9; Malayan region, 3 or 4; Australia, 24; New Zealand, 64; Hawaiian Islands, 50; North America, 17 (one of them European); South America, 10. The Hydrocampinae—the China-marks—are of great interest, as being amongst the few forms of Lepidoptera adapted for aquatic life. It is believed that all their larvae are aquatic, though of only a few is there much known. The diversity amongst these forms is of considerable interest. The habits of _Hydrocampa nymphaeata_ were long since described by Réaumur, and have more recently been dealt with by Buckler,[319] W. Müller[320] and Prof. Miall.[321] Although there are some discrepancies in their accounts, due we believe to the observations being made at different periods of the life and under somewhat different circumstances, yet the account given by Müller is we feel no doubt substantially correct. The larvae when hatched mine in the leaves of a water-plant for a short time—thirty hours to three days according to Buckler—and are completely surrounded by water, which penetrates freely into their burrows; at this period the caterpillar breathes by its skin, the spiracles being very small, and the tubes leading from {422}them closed and functionless. After this brief period of mining life, the larva moults and then constructs a habitation by cutting a piece out of a leaf, and fastening it to the under side of another leaf; it is thus provided with a habitation, but it is one into which the water freely enters, and the respiratory apparatus remains in the state we have described. The Insect passes through several moults, and then hibernates in the water. On its revival in the spring a change occurs, and the larva constructs a portable, or we should rather say free, habitation out of two large pieces of leaf of lens-shape, fastened together at the edges; but the larva has some method of managing matters so that the water can be kept out of this house; thus the creature lives in air though immersed in the water. A correlative change occurs in the structure of the skin and tracheal system. The former becomes studded with prominent points that help to maintain a coat of air round the Insect, like dry velvet immersed in water; the spiracles are larger than they were, and they and the tracheal tubes are open. One or two moults take place and the creature then pupates. There is a good deal of discrepancy in the accounts of this period, and it seems probable that the pupa is sometimes aerial, sometimes aquatic. Buckler's account of the formation of the case shows that the larva first cuts off, by an ingenious process, one piece of leaf, leaving itself on this, as on a raft; this it guides to a leaf suitable for a second piece, gets the raft underneath, and fastens it with silk to the upper portion, and then severs this, leaving the construction free; afterwards the larva goes through a curious process of changing its position and working at the two extremities of the case, apparently with the object of making it all right as regards its capacity for including air and keeping out water. He believes that Réaumur was correct in his idea that the larva regulates the admission of air or of water to the case in conformity with its needs for respiration. Müller calls special attention to the great changes in habit and in the structure of the integument during the life of this larva; but the reader will gather from what we relate as to various terrestrial Lepidopterous larvae, that these phenomena are not very dissimilar from what frequently take place in the latter; a change of habits at some particular moult, accompanied by great changes in the integument, and even in the size of the stigmata, being of frequent occurrence.

{423}The larva of _Nymphula stagnata_, a close ally of _H. nymphaeata_, has aquatic habits of a somewhat similar but simpler nature; while _N._ (_Paraponyx_) _stratiotata_ is very different. This larva is provided with eight rows of tufts of flexible branchiae, occupying the position of the spots or setigerous warts usual in caterpillars, and reminding one of the spines of certain butterfly-larvae, though they are undoubtedly respiratory filaments. These caterpillars protect themselves by forming silken webs or cases, or by adopting the case of some other larva, and are in the habit of holding on by the anal claspers, and rapidly and energetically moving the anterior parts of the body in an undulating fashion. The spiracles exist, but are functionless. The pupa lives under water, and has no branchiae; but three of the pairs of abdominal spiracles are open, and project from the body. Müller informs us that in a Brazilian _Paraponyx_ these three pairs of spiracles were already large in the larva, though the other pairs were very small, or absent. He considers that the moth of this species descends beneath the water of a rapid stream, and fastens its eggs on the stems of plants therein. _Cataclysta lemnata_ lives in a case of silk with leaves of duckweed attached to it, or in a piece of a hollow stem of some aquatic plant; it is believed to breathe, like _H. nymphaeata_, at first by the integument and subsequently by open stigmata; but particulars as to how it obtains the requisite air-supply are not forthcoming: the aquatic pupa breathes by three large abdominal spiracles like _Paraponyx_.

Musotimidae[322] is a small group of two or three genera found in Australia and Polynesia; and the Tineodidae also consist of only two Australian genera. Siculodidae is likewise a small Antarctic group, placed by Meyrick in Pyralidina; but his view is not accepted by Snellen and Ragonot. Epipaschiinae (formerly treated as a separate family) and Endotrichiinae are, according to Meyrick, subdivisions of the family Pyralidae proper, an enormous group of more than 100 genera. The Chrysauginae consist chiefly of American forms, and have not been treated by Meyrick; some of this group have been classed with Tortricidae or Deltoidae on account of the undulating costa of the front wings and the long, peculiar palpi. The Galleriidae are a small group including Insects that live in bees'-nests, and feed on the wax {424}etc.; others eat seeds, or dried vegetable substances. Three out of our five British species of this family occur (usually gregariously) in bee-hives, and have the peculiar habit of spinning their cocoons together. The mass of common cocoons formed in this manner by _Aphomia sociella_ is remarkably tough and enduring; portions of it are not infrequently picked up, and as the cocoons are of a peculiar tubular form their nature gives rise to some perplexity.

Phycitidae[323] is another very large assemblage of Insects with very diverse habits. The frenulum and retinaculum are similarly formed in the two sexes: the males frequently have the basal-joint of the antennae swollen; hence the term "Knot-horns" applied by collectors to these moths. The larvae of the species of _Ephestia_ infest groceries, and most children have become to a slight extent acquainted with them amongst dried figs; that of _E. kuehniella_ has become very injurious in flour-mills, its enormous increase being due in all probability to the fact that the favourable and equable temperature maintained in the mills promotes a rapid succession of generations, so that the Insect may increase to such an extent as to entirely block the machinery. Many of the Phycitidae feed on the bark of trees in galleries or tunnels constructed partially of silk. A very peculiar modification of this habit in _Cecidipta excoecaria_ has been described by Berg.[324] In Argentina this Insect takes possession of the galls formed by a _Chermes_ on _Excoecaria biglandulosa_, a Euphorbiaceous tree. The female moth lays an egg on a gall, and the resulting larva bores into the gall and nourishes itself on the interior till all is eaten except a thin external coat; the caterpillar then pupates in this chamber. The galls vary in size and shape, and the larva displays much constructive ability in adapting its home to its needs by the addition of tubes of silk or by other modes. Sometimes the amount of food furnished by the interior of the gall is not sufficient; the larva, in such cases, resorts to the leaves of the plant for a supplement, but does not eat them in the usual manner of a caterpillar; it cuts off and carries a leaf to the entrance of its abode, fastens the leaf there with silk, and then itself entering, feeds, from the interior, on the food it has thus acquired. Another Phycitid, _Dakruma coccidivora_ is very {425}beneficial in North America by eating large Scale-Insects of the _Lecanium_ group, somewhat after the fashion of _Erastria scitula_; it does not construct a case, but shelters itself when walking from one scale to another by means of silken tubes; it suffers from the attacks of parasites.[325] Oxychirotinae, an Australian group, is interesting because, according to Meyrick, it possesses forms connecting the Pterophoridae with the more normal Pyralids.

Crambidae, or Grass-moths, are amongst the most abundant Lepidoptera in this country, as they include the little pale moths that fly for short distances amongst the grass of lawns and pastures; they fold their wings tightly to their body, and have a head pointed in front, in consequence of the form and direction of the palpi. They sit in an upright position on the stems of grass, and it has been said that this is done because then they are not conspicuous. Perhaps: but it would be a somewhat difficult acrobatic performance to sit with six legs across a stem of grass. The larvae are feeders on grass, and construct silken tunnels about the roots at or near the surface. The Ancylolominae are included in Crambidae by Meyrick and Hampson. Schoenobiinae[326] are included by Meyrick in Pyraustidae, but this view appears not to meet with acceptance, and the group is more usually associated with the Crambidae. Most writers place the anomalous genus _Acentropus_ as a separate tribe, but it is associated by both Meyrick and Hampson with _Schoenobius_. This Insect is apparently the most completely aquatic of all the Lepidoptera, and was for long associated with the Trichoptera in consequence of its habits and of the scaling of the wings being of a very inferior kind. The males may sometimes be found in large numbers fluttering over the surface of shallow, but large, bodies of water; the females are rarely seen, and in some cases have no wings, or have these organs so small as to be useless. The female, it would appear, comes quite to the surface for coupling, and then takes the male beneath the water. The larvae have the usual number of Lepidopterous feet, and apparently feed on the leaves of plants below water just as Lepidopterous larvae ordinarily do in the air.[327] They have no trace of gills, and their {426}mode of respiration is unknown. A great deal has been written about these Insects, but really very little is known. They are abundant, though local in many parts of North and Central Europe; some of the females have, as we have said, abbreviated wings, but how many species there are, and whether the modifications existing in the development of the wings are constant in one species or locality, are unknown as yet.

FAM. 42. PTEROPHORIDAE[328] (_Plume-moths_).—Elegant Insects of small size, usually with the wings divided (after the fashion of a hand into fingers) so as to form feathers: the extent of this division is diverse, but the hind wings are more completely divided than the front, which indeed are sometimes almost entire. The group is placed by Meyrick in his Pyralidina, but there are many entomologists who look on it as distinct. It consists of two sub-families, Agdistinae and Pterophorinae, that have been treated as families by many entomologists. The Agdistinae (of which we have a British representative of the only genus _Agdistes_) have the wings undivided. Pterophorinae have the hind wings trifid or (rarely) quadrifid, the front wings bifid or (rarely) trifid. The larvae of the Pterophorinae are different from those of Pyralidae, being slow in movement and of heavy form, covered with hair and living exposed on leaves; the pupae are highly remarkable, being soft, coloured somewhat like the larvae, and also hairy like the larvae, and are attached somewhat after the manner of butterfly-pupae by the cremaster: but in some cases there is a slight cocoon. There is, however, much variety in the larval and pupal habits of the Pterophoridae, many having habits of concealment of divers kinds. We have thirty species of these lovely Plume-moths in Britain. The family is widely distributed, and will probably prove numerous in species when the small and delicate Insects existing in the tropics are more appreciated by collectors.

FAM. 43. ALUCITIDAE (ORNEODIDAE of Meyrick and others).—The genus _Alucita_ includes the only moths that have the front and hind wings divided each into six feathers. Species of it, though not numerous, occur in various regions. The larva and pupa are less anomalous than those of the Pterophoridae, though the imago is more anomalous. The caterpillar of our British _A. polydactyla_ feeds on the flower-buds of honey-suckle, and forms a {427}cocoon. The moth with wings expanded is about an inch across, and is a lovely object. It is not rare, though seldom numerous.