Moths
(Heterocera). Under this name are denoted such of the order Lepidoptera, or scale-winged insects, as are not included among the Butterflies (Rhopalocera). (See Insects for the characters that distinguish Lepidoptera from other insects.) Butterflies are a far more uniform group than Moths, and differ from them in having the antennae, or feelers, almost always clubbed at the tip, but elsewhere slender. Rhopalocera means club-horned. Their wings are usually folded back, when at rest, so as to display the lower surface, which often bears bright colours; and the body is usually slender. Moths, on the other hand, have the antennae sharp-pointed, with no club, but otherwise variable, being branched, slender, feathery, or of some other form. Heterocera means varied-horned. Some have the body slender, and the wings folded, as in Butterflies, in which case, the lower surface is seldom conspicuously coloured; but usually the body of the insect is heavy, without marked distinction between the middle body (thorax) and the hind body (abdomen); and the wings are usually folded flat on the back, the hind wings being so folded, lengthwise, as to lie entirely below the narrower forewings when at rest. In almost all, the two wings on each side are connected by a bristle, or a tuft of stiff hairs, that projects from the front edge of the hind wing, and plays in a kind of socket or ring on the fore-wing. It is more difficult to state any constant differences between the caterpillars of Butterflies and Moths than between the perfect insects, though it is usually possible for a practised entomologist to distinguish the groups even in this stage; and so also with the pupae.
Moths are of far greater practical importance than Butterflies, for the caterpillars of several species do very serious injury to fruit-trees, to potherbs, and to other cultivated plants. It is possible to ward off, or at least to lessen, the evil done by such species in some cases; but in others the insects are so well protected in the leaves, or others parts of plants, as to render remedial measures practically hopeless; and the affected parts, or the entire plants, must be destroyed to prevent extension of the injury. There is usually little difficulty in recognising the caterpillars of Lepidoptera, the only other group of insects in which somewhat similar larvae are found being the Sawflies, among the Hymenoptera. But, while they retain a strong general likeness, they yet vary exceedingly in many points, such as the number of prolegs, or fleshy legs, on the hinder rings of the body; the colour and markings; and the skin, in some smooth, in others warty, or covered with hairs, bristles, or long spines. Nor are they less varied in their habits and modes of life, though, with few exceptions, they feed on, or in, living plants. The larvae of a great majority of the Butterflies, and those of many Moths, live on the surface of the leaves, or other organs of their food-plants, exposed to full view. Frequently, such exposed larvae are brightly coloured; but, on experiment, it has often been found that they are distasteful to birds, because of unpleasant fluids thrown out by them, or of the hairs or spines on their bodies. The caterpillars of most Moths feed hidden from view in some way. The concealment is secured, by some, by hiding below the soil, or in crevices, during the day, and crawling out to feed only during night. Others roll up leaves, or spin two or more together, and feed in shelter of the cover so formed; while other combine to form large webs (see Hawthorn Caterpillars), in which they lie, and feed protected. Many others bore into the roots or stems of plants (see Leopard Moth), or between the surfaces of leaves (see Leaf Miners), and thus find food, as well as protection. A few others, chiefly small kinds, prefer dead and dried vegetable or animal products, such as corn, peas, woollen cloths, bees' combs, &c.; and these are frequently very trouble-some in houses.
The methods of remedying injuries caused by larvae of Moths, and of preventing future attacks, must depend largely on the habits of the insects, both in the perfect and the larval stages of development. They are mentioned under Insects (which see), and under special tribes or genera, noted below. Moths pass through a complete metamorphosis. The larvae seek out safe retreats in which to become pupae, or chrysalides. These retreats may be in crevices, or in the galleries made by them in the plants; or among dead leaves; or under the soil, in earthen cells, lined with silk. Less often they spin a silken cocoon, in some exposed situation, and trust to this covering for their protection. The pupae are defenceless, with the limbs all firmly bound down to the body by a hard shell or coating of chitine. The only power of motion they possess is that of wriggling some of the hinder rings of the body. In the pupa-case the Moth becomes fully developed; it then bursts the case, along the front half of the back, and crawls out, with the wings small and soft at first. But these organs at once begin to grow, and in an hour or two they reach their full size, and soon become firm, and fit for flight.
The females of various kinds of Moths (see Hybernia) never have the wings useful for flight; but in them the wings remain small, or may even be entirely absent. Moths form several well-marked tribes; though these grade into one another in such a way that it is difficult, at times, for a beginner to distinguish to which tribe certain individuals belong. The more reliable distinctive characters of the groups are noted below.
Most kinds of Moths can be reared with comparative ease, from the larval state, in confinement; hence, the life-histories of these insects are far more thoroughly known than those of any other group. But it would be beyond the scope of this work to enter on the methods of rearing, capturing, and preparing Moths for permanent preservation, despite the interest of such pursuits.
Moths are divided into two great sections; the Macro lepidoptera (meaning large scale-winged insects), seldom under 1in. across the outspread wings, and often much larger; and the Microlepidoptera (or small scale-winged insects), seldom exceeding 1in. across the wings (except in Pyralidina), and often much smaller. In both sections there are numerous species that injure cultivated plants. Each section includes several tribes, which are generally more or less characterised by the habits of the larvae, as well as by peculiarities in the structure of the perfect insects. The following are the more important tribes and families:
1. Sphingina or the Hawk Moth tribe, including the true Hawk Moths, the Humming Bird Hawk Moths (see Macroglossa stellatarum), and the Clear-wing Moths. They all have long, narrow, front wings which they move rapidly; and fly in a peculiar fashion. They have a long proboscis, or trunk; and their antennae are thick in the middle, and taper to both ends. The larvae of the true Hawk Moths are seldom very hurtful to garden plants, though that of the Death's Head Moth feeds on Potato, on Jasmine, and on Lycium barbarum; that of the Privet Hawk Moth on Privet, and those of the genus Smerinthus on Willows, Poplars, Apple, Lime, &c. They often have a straight or curved horn, or tail, at the end of the body. The Clear-wing Moths, as larvae, live in burrows, in the roots and stems of many plants, and often do considerable damage--e.g., Sesia tipuliformis in Currant branches, and S. apiformis in Poplars. 2. The tribe Bombycina includes a considerable number of Moths, usually of large size, with heavy bodies. Their wings are relatively weak, so that they--at least, the females--are not very active on the wing, and the females of some kinds are practically wingless. They usually have the proboscis small, and hardly fit for sucking up food. The males often have the antennae feathered largely on both sides; the antennae of the females, on the other hand, are usually slender. They mostly fly by day, and are often brightly coloured. The larvae are very frequently hairy and brightly coloured. Many of them are very hurtful to garden produce. The Silkworms (i.e., larvae that produce silk for their cocoons in such quantity as to be of commercial importance) belong to this tribe, and chiefly to the genera Bombyx and Saturnia. Bombyx mori is the common Silkworm Moth. Among the many species of this tribe that might be noted, we shall here mention only a few, concerning which fuller information will be found under the respective names. They are: Brown-tail, Gold-tail, and Gipsy Moths Lackey Moth Tiger Moths and Vapourer Moth
Nearly related to the true Bombycina, and often included among them, are the Ghost Swifts (Hepialidae), of which the commonest species (Hepialus humuli) feeds, in the larval state, in the roots of many plants, and is at times very hurtful to the Hop. The larvae are smooth, and dull ochreous in colour. The moths have very short, slender antennae. Closely allied to the Hepialidae are the Zeuzeridae, represented by the Goat Moth (Cossus ligniperda) and the Leopard Moth (Zeuzera aesculi); the larvae of both feed in the wood of trees. The Notodontidae, or Pseudo-bombyces, are frequently separated off as a family distinct from the true Bombyces, from which, however, they differ in no very important respect. The larvae of this family are frequently of very strange forms, with humps, or warts, or long filaments at the tip of the body, as in the Puss Moth. They mostly live on trees, and the only species among them that is common enough to be injurious to any extent is the Bufftip Moth (Pygaera bucephala), which feeds on almost any of our native, as well as on many cultivated, trees. 3 The next great tribe is Noctuina, or Night Moths, so called because of their generally flying by night. In this tribe the antennae are almost always slender; the front wings are rather narrow, the hind wings broad, and folded lengthwise. On each front wing are usually two spots, the inner round (orbicular stigma), the outer kidney-shaped (reniform stigma); and there are often two or more light cross lines. The hind wings are frequently unspotted. The body is usually thick and heavy. The colour of the whole insect is usually dull, though often the markings are very elegant when examined closely. A few Noctuae are brightly coloured, or bear metallic spots on the wings. The larvae are usually smooth-skinned and dull in colour, or are marked with bright lines, and spots occasionally. They generally have five pairs of prolegs, though, in a few genera (Plusia, &c.), the middle pairs of prolegs are small, or absent, forming a transition to the next tribe. Many of the larvae are most hurtful to garden produce. They usually go underground to change into pupae. See Mamestra, Noctua, Plusia, and Potherb Moths.
4. The Geometrina, or Looper Moths, are readily distinguished from all others, except the few Noctuae mentioned above, by the larvae being long and slender, and moving in a peculiar manner, known as looping. This is caused by the fact that the middle pairs of prolegs are useless, or are entirely wanting. Usually only the pairs on the last two rings of the body are present, and the caterpillar, in moving along, has to bring the hinder extremity forward before fixing it and pushing forward the anterior part with the three pairs of true legs. Every step thus throws the body into a loop. The moths resemble butterflies in their slender bodies, and in the size and form of the wings, as well as in their usual attitude when at rest. The proboscis in them is usually small, or wanting. The antennae are slender, or may be comb-like in the males. The colours are mostly dull, often with very elegant lines or bars, but with neither stigma on the wings; a few are bright in colour. In a few genera, the females are nearly, or quite, wingless. The pupae are usually concealed underground, in earthen cells. The larvae usually feed exposed, or may spin leaves together, to obtain protection against danger from without. The Looper Moths are far less widely hurtful than the Noctuae, yet several species may be found referred to more at length under Gooseberry or Magpie Moth, Hybernia, and Winter Moth (which see).
A knowledge of many of the Microlepidoptera, despite their very small size, is of great importance to gardeners, since they injure extremely the leaves and other parts of plants. The three great tribes of this group are as follows:
1. Pyralidina. In this tribe are contained the largest of the Micros; but they seldom do much injury to garden produce, hence they need not be dwelt on here. They frequently approach small Noctuina in habit and appearance.
2. Tortricina, or Leaf Roller Moths, are a very numerous group of small Moths, 1/2in. to 1in. in spread of wings. The front wings are broad, with the front margin close to the base peculiarly arched; and one overlaps the other when folded. In colour, the front wings are frequently green, brown, rusty-brown, yellow, &c., or are marked with peculiarly elegant spots or lines. Their palpi are short and inconspicuous; their larvae are like those of Noctuina, save in size, and possess, generally, five pairs of prolegs. They live, for the most part, between leaves, spun together, or rolled into tubes. See Leaf Rollers. The larvae are very agile, dropping from their tubes at once when a bird tries to catch them there. Many of them are more or less injurious to trees, and to cultivated plants, e.g., the Codlin Moth (Carpocapsa pomonana, and the genus Tortrix. 3. Tineina is a tribe of very wide numerical extent. It includes the smallest of the Moths, some of the species being extremely minute. They differ from Tortricina in having narrow wings, with long hind fringes; a slender body; proboscis very small, or absent; palpi long, prominent, and ascending; and the hind feet customarily long, and furnished with spurs; eyes naked. These Moths vary extremely in colour, their beauty of colouring under a microscope, being frequently unsurpassed in insects. The larvae are usually smooth, or nearly so, and of the ordinary form. They vary much in number of prolegs; five pairs is their usual number, but, in a few, there are six ill-formed pairs; in others, there are four pairs; and others are almost footless. The larvae also vary very much in their habits, some feeding exposed, others in rolled, or in mined leaves, or in clothes; and a good many make, and carry around, neat cases, for their protection from injury. Some kinds do considerable injury to the crops and to trees; but the Tineina, as a whole, are far more injurious to field crops than to gardens. The pupae are usually protected, as in Tortricina, in a web, or cocoon, spun by the larvae among their food. See Hawthorn Caterpillars.
Pterophorina and Alucitina, or the Plume Moths, are small Moths, in which each wing is divided, lengthwise, into from two to six segments, or "plumes," resembling small feathers. They are of small size, and do little harm to cultivated plants, or to field produce in general.