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 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, 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 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, 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.