Chapter V: Part 5

Sucking mouth-parts, forming a “proboscis” made up of the two very long maxillæ, spirally rolled up under the head when not in use (Fig. 92), and adapted for sucking honey. There are some forms which take no food in the adult condition, and in which the proboscis is short; in a few species of hawk-moths, this organ is even longer than the body. The larvæ (“caterpillars”) have biting mouth-parts. The body of a butterfly or moth is covered with hair-like structures developed by the skin; in the wings these are broader, have a characteristic appearance (Fig. 93), and partially overlap one another. These scales cause the colours of the wing. They can easily be wiped off, leaving the corresponding part of the wing transparent and clear as glass. In many species (all hawk-moths, many owlet moths) there is a _wing-hooklet_, i.e. the hind wing has a spine or a thick brush which grasps a band-like area of the fore wing. In this way the two pairs of wings are held together. The females of a few species of spinner and looper moths are wingless, or only possess short flap-like wings useless for flight. The metamorphosis is complete (p. 89); the larvæ are true caterpillars; the pupæ are obtectate (p. 93). Many caterpillars creep into the ground to become pupæ, and spin no investment at all (_e.g._ hawk-moths). Others make a cocoon, which may consist of threads loosely woven together or may be of firm texture (Fig. 60). The cocoon consists chiefly of silk, a substance secreted in a spinning gland, and exuding to the exterior on the lower lip; but minute particles of sand or earth, and fragments of wood gnawed off by the caterpillar, may be stuck in the cocoon. The pupæ of butterflies are naked, without cocoon, but are fixed by threads to leaves, tree stems, walls, hedges, etc. A distinction is drawn between girdled and suspended pupæ; the first are fixed by a silk band, which surrounds them, and the head is directed upwards, while the latter are suspended by the tip of the abdomen (Fig. 94). The time required for the development of the perfect insect from the pupa is not always the same, depending not only upon the species, but also upon the time of year. The summer generation of the large white spends scarcely fourteen days in the pupa stage, the winter generation eight months.

Family: =Diurna= (_Butterflies_).

Body relatively weak and thin; wings very broad, not very long relatively. No wing-hooklet (_see above_). Wings folded together above in a state of rest, so that their upper sides touch. Antennæ thickened in a club-like way at the tip. The caterpillars possess five pairs of pro-legs; they are usually almost devoid of hair. There are, however, a few (_e.g._ the caterpillar of the peacock butterfly, Fig. 94) which possess hard, spine-like, much-branched bristles. The naked pupæ are sharp cornered; some are girdled, others suspended (p. 137).

FIG. 94.—The Peacock Butterfly (_Vanessa io_), with pupa, and larva
suspended before passing into the pupa state.
]

Among butterflies with larvæ that become suspended pupæ are the =Red Admiral= (_Vanessa atalanta_), the =Peacock= (_Vanessa io_, Fig. 94), the =Fritillaries= (_Argynnis_), the =Meadow Browns= (_Hipparchia_), etc.; and among those with girdled pupæ the =Swallow Tail= (_Papilio machaon_), the =Whites= (_Pieris_), etc.

The =Cabbage White=, or =Large White= (_Pieris Brassicæ_).

_Butterfly_: Length a little over an inch, span of wing 2½ inches. Both fore and hind wings milky white, the former black at the root, on the front edge, and the outer angle; also a black patch on the inner margin of the fore wing, passing on to the front margin of the hind wing. The female possesses, in addition, two round black patches on the middle of each fore wing. Under side of the fore wings milky white, yellow at the tip, blackish at the root; under side of the hind wings yellow, with black dots. _Caterpillar_ (Fig. 95): As much as 1⅓ inch long; greenish, or sulphur yellow, with black dots. Head and dorsal side of last segment of the body grey with black spots. Young specimens are of a very bright green with black wartlets closely crowded together.

FIG. 95.—The Cabbage White (_Pieris brassicæ_) female laying her eggs;
caterpillar, and pupa.
]

From the pupæ which have lived through the winter butterflies emerge in May, and lay their golden yellow eggs in small heaps on the under sides of the leaves of rape, mustard, and cress, also on charlock and such-like cruciferous weeds. The caterpillars of this first generation are hatched in fourteen days, and rarely do any harm, since they only appear in small numbers. They develop rapidly, and during the last days of June become pupæ on the branches and leaves of the plants they live on; the butterflies appear in July. Owing to their rapid development the caterpillars and pupæ of this first generation are but little exposed to the attacks of enemies (ichneumons, birds, etc.). Only a few of them die, therefore, if the weather is favourable. As a result of this, the July butterflies and the eggs laid by them are relatively numerous, so that the number of caterpillars appearing in late summer may be very large. These caterpillars, however, live almost exclusively on the various kinds of cabbage and kohl rabi, and it is this second generation which in many years is so harmful. At the beginning of August the caterpillars are ready to become pupæ, and for this purpose they seek tree stems, hedges, walls, etc. The pupæ now formed live as such through the winter. During this period, however, they are exposed to many dangers (damp, cold, sudden alternation between very low and very high temperatures; ichneumons, birds), and most of them perish, so that only a few butterflies come out the following spring, and lay but a few eggs. It is therefore obvious that the first generation of caterpillars (May, June) is much less numerous than the second generation occurring from late summer to autumn. Under exceptionally favourable conditions even a third generation may appear, since caterpillars of the second generation are able to become pupæ at the beginning of August; and these pupæ, instead of remaining as such over winter, become butterflies the same month. These, again, lay eggs from which the caterpillars of the third generation are hatched, which, however, are not always fully developed before the advent of the cold weather, and in this case perish. It is clear that, in the case of pupæ which develop into butterflies during August in about fourteen days, the unfavourable influences have either no effect (unfavourable weather) or but little (ichneumons, birds), so that the butterflies appear in flocks, which wander into other regions, since they have themselves, when larvæ, devoured the cabbage and turnip plants. In reference to the damage effected by the caterpillar, it may be observed that only the chief veins of the leaf are left, and the margins are not spared. _Remedies_: Collection of the little heaps of yellow eggs and the young caterpillars, which are blackish and live together in small companies; the planting of a few small hemp plants in the cabbage fields to be protected, by which the butterflies will be kept away.

The =Garden White=, or =Small White= (_Pieris rapæ_).

FIG. 96.—The Garden White (_Pieris rapæ_), male.
]

FIG. 97.—The Garden White (_Pieris rapæ_), female, caterpillar.
]

_Butterfly_ (Figs. 96 and 97): Length rather less than an inch, span of wing two inches; very much like the cabbage white. Base and tip of the fore wing not of such a deep black colour; the black patch in the inner margin of the fore wing is usually absent in the female. The male, however, very often has a black patch in the upper side of the fore wing. _Caterpillar_: Just over an inch long. Dull green; a longitudinal yellow line on the back; also the black stigmata are connected by a yellow line. Habits as in the preceding species; the female, however, lays her yellow eggs separately, and not in heaps, and the second generation of caterpillars usually become pupæ somewhat later in the year. Collecting is more difficult than in the preceding species, since the young caterpillars live independently, and their colour makes it difficult to recognize them on the green cabbage leaves.

The =Green-veined White= (_Pieris napi_).

_Butterfly_ (Fig. 98): As large or somewhat smaller than the preceding species. Wings milky white on their upper side; fore wings dusted with black on their front margin, tips, and ends of the ribs. Two spots on the middle of the fore wing in the female, one or none in the male. Under side of the hind wings yellow; under side of the veins dusted with greenish grey. _Caterpillar_: A little over an inch. Dull bluish-green, with minute blackish tubercles above, and whitish ones below. A yellow longitudinal line on each side connecting the black spiracles, which are bordered by reddish yellow. Very like the preceding species in the larval condition. Habits as in the preceding species, but this is less common.

FIG. 98.—The Green-veined White (_Pieris napi_).
]

Family: =Noctuidæ= (_Owlet Moths_).

Night-flying moths, of medium size and dull colour, with smooth-haired bodies. Antennæ long and thin, thread like,—comb-shaped only in the males of a few species; wings powerful, lie in a roof-like way when at rest; almost always a wing-hooklet. Caterpillars usually hairless; mostly with five pairs of pro-legs, a few with four or three pairs. The owlets pair at night; they also fly about during the day, even in bright sunshine. Flight strong and rapid, but always in fits and starts. Almost all species lay their eggs separately, and on herbs, only a few species on trees. The caterpillars are very much scattered, and the damage caused by them is never great, except in spots here and there,—on the contrary, when they increase to a great extent they spread over a wider area. Several species are harmful to agriculture.

The =Surface Caterpillars= (Species of _Agrotis_)

are stout caterpillars, 1⅕ to 2 inches long, with five pairs of pro-legs, and shining transparent external skin. They remain in the ground during the day, feeding above ground at night, and also in the daytime when the sky is much overcast. When touched they bend themselves into the form of a C. There are in Britain several species of surface caterpillars which have these habits, but I will only describe here, to begin with, the commonest kind:—

FIG. 99.—The Common Dart or Turnip Moth (_Agrotis segetum_) with
Caterpillar.
]

The =Common Dart= or =Turnip Moth= (_Agrotis segetum_ or _A. clavis_).—_Moth_ (Fig. 99): Length almost ⅘ of an inch. Span of wing about 1⅘ inch. Fore wings small, ash-grey or brownish, with many dark patches and similar markings. Hind wings in the male, bright grey to snowy white; in the female, brownish grey. _Caterpillar_ (Fig. 99): Up to two inches, earthy grey, occasionally somewhat greenish. Head and prothorax darker. The time taken by the caterpillars to complete their development differs according to the plants attacked, and it is therefore easy to understand why the moths should be seen flying about from the first half of May right on into the autumn, without having recourse to the improbable hypothesis of two successive generations. The eggs are consequently laid at very different times, and are always deposited singly in the soil in the neighbourhood of plant roots, or else in the low-lying leaves and stems of various herbs. The caterpillars hatched from these are destructive earlier or later, according to the time of egg-laying. Most specimens are half grown in winter; these continue their destructive work the following spring. In autumn they attack the roots of winter grain (rye and wheat), rape, and species of cabbage; they also bore readily into turnips and potatoes. In spring, after the winter rest, they continue to attack the roots of winter grain, winter rape, etc., or fleshy underground parts (turnips, potatoes) developed in the interim, or the roots of summer plants (summer grain, buckwheat, summer rape, vegetables, etc.). On clear days the caterpillars always remain hidden in the soil; and those which have bored into juicy underground parts of plants (turnips, carrots), do not leave their abode during the day, but the others, both during the night and on cloudy days, come above ground to attack the leaves and stems of young plants. In exceptional cases the caterpillar is mature by the beginning of winter, in which case it hybernates in the soil as a brown pupa. The moths escaping from such pupæ naturally appear earlier than others. As a rule, the caterpillars do most damage to the winter crop in autumn, wandering about a great deal; in many cases they gnaw through the main root, thus quickly killing the plant attacked, from which they proceed to another. _Remedies_: When the caterpillars have done much damage in late summer, it is recommended to leave the field alone till October, then to plough it up and sow the winter grain. By putting off the seed-time in this way, the caterpillars will have lost their activity when the corn germinates, and the winter crop will thus escape them. Besides this, the preceding ploughing will bring many caterpillars to the surface, where they will become the prey of birds, or, if not, can be collected. Warm soils, especially those manured with horse dung, are most infested by the caterpillars; and the use of warm kinds of manure should, therefore, be avoided in regions which have much to fear from these insects. Where everything has been destroyed, a thorough ploughing is desirable. Swine may also be driven in during autumn, and will grub up and devour the caterpillars. In this case, sowing will take place the following spring.

Other _Surface Caterpillars_, which have pretty much the same habits as the preceding, are those of the =Heart and Dart Moth= (_Agrotis exclamationis_), the =Wheat Moth= (_A. tritici_), and the =Thick-bodied Surface Caterpillar= (_A. ravida_ or _A. crassa_).

The =Cabbage Moth= (_Mamestra brassicæ_).

_Moth_ (Fig. 100); about ¹¹⁄₁₂ of an inch long, span of wing 1⅗ inch. Fore wings shining brown, with yellowish and black marbling; each patch having a dark outline; a yellowish zigzag line on the outer margin. Hind wings shining yellowish-grey brown. A strongly developed crest in the middle line of the thorax. _Caterpillar_ (Fig. 100): 1⅗ inches, cylindrical. Bright or dark green, brownish green, or greenish brown. On the back a dark longitudinal stripe, divided into two halves by a narrow white longitudinal line. A whitish line running along each side; between this and the dorsal line a dark transverse streak on each segment. The brown pupa (Fig. 100) remains in the soil during the winter, and is not invested in a cocoon. The moth appears in May; during the day it rests on windows, in barns, etc. The greenish yellow eggs are laid separately on the leaves of cabbages (sometimes also on lettuces and turnips). The caterpillars, which appear in fourteen days, creep about actively between the leaves. Within a month they are full-grown, and become pupæ in the soil. At the end of July and in August the summer generation of moths appears. From the eggs laid by these are hatched a second generation of caterpillars, which are always much more numerous than those of the first. From August to October they are found in all kinds of cabbage, especially compactly headed kinds and cauliflower. At first they eat holes in the leaves, leaving, however, the chief veins and usually the edges. Later on they eat right on into the heart of the cabbage. They fill their burrows with excrement, and the attacked plants begin to rot internally. The full-grown caterpillars creep out and become pupa in the soil. _Remedy_: Collecting the caterpillars while they are still on the outer leaves.

FIG. 100.—The Cabbage Moth (_Mamestra brassicæ_), with caterpillar and
pupa.
]

The =Vegetable= or =Lettuce Moth= (_Mamestra oleracea_).

_Moth_: ⅗ of an inch long; span of wings about 1⅖ of an inch. Fore wings dark rusty brown, darker on the nerves, dusted with white. Hind wings reddish white. Head and thorax like the fore wings; abdomen like the hind wings. _Caterpillar_: Up to 1⅗ inch; dirty greenish grey, or olive green, irregularly bestrewn with dirty white dots. The caterpillars feed on cabbages, lettuce, asparagus, and other vegetables. Those of the first generation (June and July) hollow out lettuce stalks before the head begins to be formed; those of the second generation (August and September) feed on cabbage or asparagus leaves. The first generation of moths appear in May, the second in the first half of August.

The =Pea Moth= (_Mamestra pisi_).

_Moth_: About ⅖ of an inch long; span of wings about 1⅖ of an inch. Fore wings bright reddish brown with bluish-grey markings, and a yellowish longitudinal streak. Hind wings reddish grey. _Caterpillar_: 1⅘ of an inch; cylindrical; slender. Back dark greenish or brown red; closely and tolerably regularly veined with dark lines, and with two sulphur yellow longitudinal streaks on the back and one on each side. Head, belly, and feet flesh red. If the caterpillar is touched it moves the front part of its body about here and there, and then lets itself fall down. The moths appear in May and June; the caterpillars are found from July to September on peas, vetches, beans, clover, lupins, sorrel, orach, heath, willow, birch, and yet other plants. Seldom very destructive.

The =Grass-root Moth= (_Hadena monoglypha_, or _H. polyodon_).

_Moth_: About ⅝ of an inch long; span of wing 1⅘ inches. Fore wings longish; yellow brown blended with dark brown and white; the tips are coloured most brightly. Three black rays on the fore wing; hind wings brown grey. _Caterpillar_: About 1⅗ inches long, ⅓ of an inch broad, with sixteen feet. Grey or reddish white, more or less shining. Head, prothorax, the last body segment and warts black. At the end of July and during August the female lays her eggs separately on the bases of grass haulms and leaves. The caterpillars creep out at the end of August, and, especially after their hybernation (in April and May), attack meadow grasses, biting through the leaves and haulms at their bases, immediately above the surface of the ground, and devouring, as it were, passages through the grass. The reddish brown pupæ rest in the soil.

The =Couch-grass Moth= (_Hadena basilinea_).

_Moth_: Nearly ⅘ of an inch long; span of wings 1⅗ inches. Head and back rust-coloured or reddish grey, in the male with a large tuft of hairs. Fore wings coloured like the back, with two transverse lines in the middle, and brighter and darker marks as well. Hind wings bright brown, with a faint golden sheen, and with a yellowish fringe. _Caterpillar_: 1⅕ to 1⅖ inches long, with sixteen feet, bluish grey, somewhat brownish, with dirty white longitudinal lines; greenish belly, and large bright brown head. The moth lays the eggs in little heaps on the stems and leaves of grass plants. The damage which the caterpillars effect among meadow grasses is inconsiderable; but they sometimes appear in considerable numbers on grain-plants, and are then very destructive. The insects are chiefly found on dry high-lying land, which is consequently most liable to the attacks of their larvæ. After hybernation they feed on grass or the leaves and stems of young grain-plants, and change in the soil into stout, smooth, yellowish-brown pupæ, devoid of cocoon. _Remedy_: In case the caterpillars have got into the crop, threshing should take place as soon as possible, or, after hybernating, they will continue to devour the grain in the barns.

The =Wheat-haulm Moth= (_Luperina didyma_).

_Moth_: Span of wing 1⅕ inches. Individual specimens differ very much from one another: brownish, greyish yellow to ochre yellow, with various dark and light markings. _Caterpillar_: With sixteen legs, and over an inch long in full-grown specimens (May); thin, spindle-shaped; stiff; bright shining green, with two broad dark red lines on the back. The caterpillars live in the stalks of wheat plants, and other gramineous forms, hollowing them out; they hybernate when tolerably young. In spring they continue to hollow out the wheat plants, going from one stalk to another. The plants attacked quickly have their leaves turned to a rusty colour, and they sicken or even die.

The =Grass Moth= (_Charæas graminis_).

_Moth_: Length ⅗ of an inch; span of wings about 1⅓ inches. Antennæ of the male comb-like. Fore wings short, of a brownish-red, olive brown, or dirty olive-green ground colour, with three whitish patches, and darker markings. Hind wings yellowish grey, brighter at the roots. _Caterpillar_: With sixteen legs; 1⅘ inches long; bronze grey, back more of a bronze brown, with three narrow bright longitudinal streaks. Head ochre yellow. The moth lays her some two hundred eggs during July, in little heaps at the bases of the grass haulms and leaves. The caterpillars hide during the day, and feed at night. They are very injurious even in the autumn, but become insatiable the following spring, always devouring the lowest parts of the haulms and leaves, so that the upper parts die off. They wander in large companies from one field to another. In June they become pupæ of a shining reddish brown below the surface of the soil or under sods. _Enemies_: swine, moles, shrews, rooks, wagtails, ducks, fowls. _Remedy_: Driving in swine, where this is practicable.

FIG. 101.—The Grass Moth (_Charæas graminis_) and its caterpillar.
]

The =Darnel Moth= (_Neuronia popularis_).

_Moth_: Length rather less than ⅘ of an inch; span of wings nearly 1⅗ inches. Much variegated, beautiful. Fore legs reddish brown, with peach-coloured glow; all the nerves and several markings yellowish white, and dark markings as well. Hind wings yellowish, and abdomen white. Head and thorax brown, mixed with yellowish white. _Caterpillar_: Over two inches long, and about one-third of an inch thick; 16-legged; tapers at both ends. Has an oily lustre. Dorsal side of a bronze brown, sharply marked off by a yellowish line from the bright brownish grey ventral side, and traversed by three longitudinal bright brown lines, which in young specimens are almost white. Habits pretty much like those of the preceding species.

The =Silver Y Moth= (_Plusia gamma_).

FIG. 102.—The Silver Y Moth (_Plusia gamma_), with caterpillar and
pupa.
]

_Moth_: About ⅝ of an inch long; span of wings 1¾ inches. Dark grey, mixed with a reddish tint, and darkly marbled. About the middle of the fore wing there is a very obvious gamma (γ), or Y-shaped mark. Hind wings bright brown at the root, darker at the margins, with a whitish fringe. A crest of hairs on the dorsal side of the thorax. _Caterpillar_: 12-legged. It bends its body like a looper (Fig. 102). Length 1 to 1⅕ inches. Ground colour green; but there may be variations in this from a dirty green to a brownish colour. Six fine longitudinal lines on the back, and a yellowish line above the legs. The caterpillar is almost naked, only possessing a few small, isolated bristle-like hairs. _Habits_: At least two generations, and sometimes as many as five in two years. The Silver Y Moth generally hybernates as a half-grown caterpillar, but sometimes also in the pupa, or moth state. The caterpillars may therefore be met with the whole year; but they are usually most abundant from the end of June to the middle of August, and, under favourable conditions, may become an agricultural pest. They devour the leaves of almost all wild and cultivated plants (except grasses, corn, and trees), and are especially fond of leguminous plants (peas, vetches, clover), flax, beet, rape, cabbage, and buckwheat. The moths mostly appear in May, but also in July, and later on in the summer, especially on clear days. The female lays her numerous bright green eggs, some four hundred in number, separately, on the leaves of the above-named plants. The caterpillars are not always easy to see, owing to their greenish colour; under favourable conditions they may pass through the whole of their development up to the moth stage in from six to seven weeks. In some years they appear in such large numbers, that almost all the cultivated plants found in the fields of an infested region are utterly spoilt by them, excepting the corn. _Natural enemies_: Starlings, all sharp-beaked singing birds haunting fields; sparrows; ground beetles, rove beetles, and the larvæ of these families; several ichneumon flies, parasitic fungi. _Remedies_: Driving in poultry, where practicable. Collecting, _e.g._ by means of a machine invented by L. Dehoff, of Gutenberg, near Halle. “Several troughs with steep inner walls are fastened together by laths, at distances equal to those between adjacent furrows, and besoms are fixed to the laths. These troughs are drawn along like sledges by a horse walking in the furrows, and the caterpillars are swept by the besoms into the troughs, from which they are collected in sacks at the ends of the furrows. With this cheap machine about twelve acres per day can be cleared” (Taschenberg).

Family: =Pyralidæ= (_Snout Moths_).

Small moths with thread-like antennæ, comb-like in the males of a few species, with tolerably large eyes, and very large labial palps often stretched out in front like a beak (Fig. 103). Fore wings of an elongated triangular shape. Wing booklets. Legs tolerably long. Caterpillars slightly hairy, with four or five pairs of pro-legs.

The =Rye Snout Moth= (_Pyralis secalis_).

_Moth_: ⅗ of an inch long, span of wings 1⅕ inches. Wings elongated, whitish grey, with an A-shaped patch on the fore wings. _Caterpillar_: Rather more than ⅖ of an inch long; green, streaked with brown, 16-legged, with a brown head, and tapering at both ends. _Habits_: The caterpillar lives during June in the rye haulms, hollowing them out. As a result of this, the ears remain hidden between the leaves and leaf-sheaths, and it often happens that only the tips of the awns appear externally. No grain is formed; the ears first become white and dry, and then fall off.

The =Hop Snout Moth= (_Hypena rostralis_).

FIG. 103.—The Hop Snout Moth (_Hypena rostralis_).
]

_Moth_ (Fig. 103): Length rather less than ⅖ of an inch; span of wings 1⅕ inches, or more. Fore wings usually brownish, somewhat scalloped on the fringed outer margins; a zigzag black line near the base; in the middle, near the front edge, a patch bordered with white, and behind this a dark longitudinal streak. Hind wings dull grey, with a silky sheen. _Caterpillar_: At most one inch long, 14-legged, very slender, green, with a dark middle line and two white side lines. Very active; wriggles about on the ground like an eel. _Habits_: The moth is on the wing at the beginning of August, the second generation in August; the latter hybernates in outhouses, barns, summer-houses, etc. The eggs are laid on wild and cultivated hops, also on stinging nettles. The caterpillars are found on the hop plants, especially in June; they sometimes entirely devour the leaves, with the exception of the nerves. In July they become pupæ, either between the leaves or on the soil, and are invested in a grey cocoon. The moths appear at the beginning of August, and give rise to a second generation of caterpillars, from which, after the pupa stage, the moths which live through the winter are developed.

The =Cabbage Snout Moth= (_Botys forficalis_).

_Moth_: Length about half an inch. Span of wings rather over one inch. Fore wings sharply bent in front before their sharp tips; rusty yellow, somewhat darker on the nerves, with rusty brown transverse streaks from the outermost corners to the middle of the hinder margin, and with other reddish brown markings. Hind wings and body shining straw yellow. _Caterpillar_: ⅘ inch long, 16-legged, tapering in front and behind. Yellowish green, with indistinct longitudinal lines and bright brown head. A few small yellowish-green hairs. _Habits_: The first generation appear in small numbers in May. The caterpillars hatched out from the eggs of these live (May and June) on the leaves of cabbages and wild cruciferous plants. They always shelter themselves between the leaves, and spin a few thin threads across the entrances to their abodes. The caterpillars burrow horizontally in the earth, and there become pupæ invested in cocoons. The moths of the second generation appear in August; in autumn the caterpillars hatched from their eggs damage cabbages, sometimes to a large extent. In October they burrow into the soil, where they hybernate. _Remedy_: Deep digging or ploughing after the crop, by which the larvæ invested in webs are buried deeply, and consequently for the most part killed.

The =Mother-of-pearl Moth= (_Botys margaritalis_ = _B. extimalis_).

_Moth_ (Fig. 104): Length nearly ⅖ inch; span of wing over 1⅕ inches. Fore wings bright sulphur yellow, with large rust-coloured patches, and two rusty yellow transverse lines. Hind wings shining straw yellow; all four wings with a mother-of-pearl sheen. _Caterpillar_ (Fig. 104): ⅘ inch, 16-legged, yellowish, head and neck-shield black. Body with a broad, grey, longitudinal streak on each side. Four longitudinal rows of dark brown warts. _Habits_: The moth is on the wing in June and July, and lays the longish ovoid eggs on cruciferous plants (rape, radish, several wild forms). The caterpillar lives concealed in a white web, and gnaws holes in the pods, into which it inserts the forepart of its body for the purpose of devouring the still green seeds. The attacked pods, owing to the presence of round holes in them, look something like flutes or fifes.

FIG. 104.—The Mother-of-pearl Moth (_Botys margaritalis_), with larva
(1) and injured pods.
]

The full-grown caterpillars burrow into the soil, where they hybernate in a delicate web. _Remedy_: Compare the preceding species.

Family: =Tortricidæ= (_Leaf-rollers_).

Small, thick-set moths (Fig. 105), with smaller palps than the snout moths. Fore wings broad at the root, with straight or somewhat curved outer margins. Hind wings as broad, or even broader, than the fore wings. When at rest the fore wings lie in a roof-like way. They usually possess many characteristic markings. Hind wings greyish, without markings. Antennæ thread-like. Caterpillars hairless, or only slightly hairy; 16-legged: many kinds live in leaves, which they roll up; others in twigs, buds, and fruits, which they hollow out.

The =Fawn-coloured Pea Moth= (_Grapholitha nebritana_ = _G. pisana_).

_Moth_ (Fig. 105): Length ⅜ inch; span of wings about ⅖ inch. Fore wings fawn-coloured, with metallic sheen; alternating short, white, and dark lines on the front margin. Hind wings black, with bronze sheen and white fringe. _Caterpillar_: ⅓ inch long; 16-legged; pale green, with brown or black head, neck-shield, and last body segment. The thoracic legs are black. Dark warts on each segment. _Habits_: Compare the succeeding species.

FIG. 105.—The Fawn-coloured Pea Moth (_Grapholitha nebritana_).
]

The =Crescent Pea Moth= (_Grapholitha dorsana_).

_Moth_: Somewhat larger than the preceding species. Fore wings olive brown, with many small short white lines on the front margin. A yellowish white crescent on the middle of the hinder margin. Hind wings brownish. _Caterpillar_: Nearly ⅖ inch long, 16-legged, orange yellow, with brown or black head, neck-shield, last body segment, and thoracic feet. Covered with brownish-yellow warts. _Habits_: The moths fly about in large numbers round the pea blossoms, always a short time after sunset. The female lays one, two, or at most three eggs, on a very young pod, or on an ovary. In fourteen days the caterpillar is hatched, bores into the pod, and attacks the peas. The opening made in the margin of the pod closes up again. The pod generally ripens early. When it opens, the full-grown caterpillars creep out, and become pupæ in the soil, within a web, where the pupa lives through the winter. The peas attacked are always covered, while in the pod, with the coarse-grained excrement of the caterpillars, and are often united two or three together by web fibres. _Remedy_: Deep digging of the soil before the winter, or, still better, deep hoeing as soon as the pea crop is gathered in. In this way many of the caterpillars or pupæ hidden in the soil will be destroyed.

Family: =Tineidæ= (_Leaf-miners_).

FIG. 106.—The Larch Moth (_Coleophora laricella_).
]

These moths are the smallest of the Lepidoptera. Like the snout moths, they have strongly developed labial palps, but are distinguished from them by their small wings; the hind wings are especially small, and have sharp tips. The extent of the wings is increased by a broad marginal fringe. When at rest, the wings slope like a roof, and the fringe near their tips is often turned upwards. Antennæ thread-like, tolerably long—in the males of a few species may even be very long. Caterpillars slightly hairy, with five, or, rarely, four pairs of pro-legs. To this family belong the well-known =Clothes Moth=; the =Corn Moth=, living in stored-up grain; and also—

The =Carrot Moth= (_Depressaria nervosa_ = _Hæmylis daucella_).

_Moth_: Length ⅖ inch. Span of wings rather over ⅘ inch. Fore wings reddish-grey brown, blackish on the nerves, and with scattered whitish markings. Hind wings more of a grey brown. Thorax and abdomen very shiny, and somewhat brighter than the wings. _Caterpillar_: Nearly ⅖ inch long, tolerably thick, especially in the middle, and variegated. Head, thorax, and last body segment shining black, the last two regions with reddish-yellow margin, and the thorax, in addition to this, divided into right and left halves by a longitudinal yellow line. The rest of the body is olive green; a broad orange-coloured line divides it into a darker dorsal and a lighter ventral side. On the back many ill-defined warts of a shining black colour. _Habits_: In March and April many of the carrot moths which have survived the winter come out of their hiding-places; they only fly at night. The eggs are laid separately on umbelliferous weeds, carraway, or carrot plants. The caterpillars are first seen when the plants flower; they live on the flower-stalks, which they bind together by a few threads, and devour the flowers and young fruits, sometimes even the flower-stalks. The caterpillars are very active, and let themselves down by a thread when disturbed. Usually they are fully grown in five weeks, and then bore into the stalks of the plant, where they become pupæ. It is not known whether there are one or two generations. The caterpillars are found at very various times, from May to August.

The =Diamond-back Moth= (_Plutella cruciferarum_ = _Tinea xylostella_).

_Moth_: About ¼ inch long; span of wings ⅗ inch. Fore wings small, lancet-shaped, with long fringes. Ground colour yellowish brown, darkly speckled. Hind wings brownish grey, small, strongly fringed. When at rest the long fringes form a sharp backward and upwardly directed comb, while the antennæ are applied together and stretched straight forwards. _Caterpillar_: About ¼ inch long, tapering in front and behind. A beautiful green, with a black head. Lives hidden under a very thin web or under a few fibres, on the lower side of the leaves of cabbage, rape, and other crucifers. _Habits_: The pupa lives through the winter; the moths emerge in May, and fly about in the evening. Two generations; the first generation of caterpillars in the first half of July, the second in late summer. The second generation is particularly apt to be destructive to cabbage. Pupæ found on the leaves of the plants attacked, and surrounded by a thick web.

SIXTH ORDER: Hemiptera (HALF-WINGED INSECTS).

FIG. 107.—Left pair of wings of a Bug.
]

The mouth-parts are modified into a sucking and piercing beak. Head small. Legs usually slender, with two- or three-jointed feet. Wings are absent in several species (_e.g._ bed bugs); in one section (_e.g._ fruit bugs) the fore wings are half of leathery, half of membranous texture (Fig. 107); in others, all four wings are membranous (winged plant lice), or the fore wings are somewhat harder than the hind wings (frog-hoppers). Incomplete metamorphosis (p. 89). None of agricultural importance except—

Family: =Aphidæ= (_Plant Lice_).

FIG. 108.—The Bean Aphis (_Aphis papaveris_); a larva of the same
below.
]

Long, five- to seven-jointed antennæ. Long thin legs, no power of springing. Sucking beak long and thin. In the same species there are both winged and wingless aphides, mostly the latter. In autumn, male and female specimens are found. After pairing, the latter lay their eggs, which are destined to live through the winter. The aphides hatched from these the following spring are all females, but are distinguished from those of the previous autumn by producing living young, which contain at the time of their birth the germs of a new generation. The number of young produced by a single female, and the number of generations appearing within the year, vary according to the species. There are species in which each female bears from eighty to one hundred young, and nine to sixteen generations succeed one another in the year. In autumn males and egg-laying females once more appear. As a rule the eggs live through the winter, but the insects themselves may also do this. I must add that there are constant differences within the boundaries of the same species according to the habitat, and especially in the species which regularly wander, either from one plant to another, or from the leaves to the roots. But since the species injurious to agriculture do not migrate in this way, nothing further need be said on the point. As aphides suck plant juices during the whole of their lives, and have enormous reproductive powers, they are very destructive. They suck from stems and leaves the juices which would otherwise be used by the plants themselves for growth or for the production of flowers and fruit, and bear young, which bore their beaks into the same part in the immediate neighbourhood of their mother, and quickly begin to multiply in their turn. In this way, colonies consisting of a hundred or more individuals are regularly formed (_e.g._ on peas, beans, roses). A plant part attacked in this way shrivels for want of nourishment, and the aphides upon it would die if they did not wander elsewhere. The third generation usually contains, not only wingless individuals, but also others which, after repeated moults, fly away and start a new colony in another plant. Since aphides have many enemies (starlings, sparrows, grasshopper warblers, etc., lady-birds and their larvæ, drone fly larvæ, lace fly larvæ), and are often killed in large numbers by wind and rain, it only occasionally happens, particularly in dry summers, that they entirely or largely destroy the plants they infest. They injure plants, not only by drawing away their nourishment, but also by the separation of a sugary sticky fluid from the anus. If the minute drops of this fluid fall from the upper parts of an infested plant to the lower (garden and field beans), or from the leaves of an infested tree to the plants growing at its foot, or, as sometimes happens, are carried by the wind to more distant plants, great damage may be caused. The fluid evaporates and leaves behind a shining sticky substance, which closes up the stomata of the leaves, and partially checks exchange of gases (assimilation and respiration). Particles of dust, sand, and smoke carried by the wind, and also the cast skins of the aphides, stick to the surface of the leaves and render exchange of gases still more difficult. The leaves develop brown dirty patches, and die off. Besides this, the spores of disease-producing fungi, carried by the wind, stick very easily to the places covered by the sweet fluid, and readily germinate in it. Aphides may thus be the indirect cause of several diseases (_e.g._ smut). These insects are destructive, therefore, to other plants than those infested by them. _Remedies_: Spraying with any one of the fluids destructive to them—soapy water; a decoction of quassia chips; tobacco water, not too concentrated; Nessler’s fluid (1½ ozs. soft soap, 2¼ ozs. tobacco mixture, 2 ozs. fusel alcohol, half a pint ordinary alcohol, diluted with rain water up to a quart: when used, mix with one-fifth the quantity of rain water); Koch’s fluid (2 lbs. soft soap dissolved in half a gallon of hot water; ½ lb. of quassia chips extracted for twelve hours in 5 quarts of rain water, and the fluid thus obtained boiled and filtered. It is then added to the soap water, and the whole brought up to 10 gallons by addition of rain water). Spraying with one of the above-named fluids must be renewed in a short time, so as to reach all the aphides wherever possible; if even a few remain untouched, there will soon be a large number again. A warm evening is best for the spraying. Infested plants can also be strewn with finely powdered substances, or these may be scattered over them by means of a small bellows. Since such substances should remain on as long as possible, they should be used after rain or early in the morning, when the dew is still on the leaves. Among powdered matters suitable for the purpose, the following may be named: gypsum, lime, tobacco, wood-ash, insect powder (prepared from the flower-heads of Persian species of chrysanthemum and from tansy heads). It must also be pointed out, that these remedies must be employed as soon as the insects begin to show themselves in considerable numbers; it is not desirable to delay till the infestation has made considerable headway, as it is then much more difficult to get a satisfactory result. In some cases, it is desirable to cut off and burn or otherwise destroy much infested parts, or those parts on which the insects first begin to multiply (_e.g._ early cutting off of the tips of the stems in field and garden beans).

The species of aphis which most commonly occur upon cultivated plants are:—The =Bean Aphis= (_Aphis papaveris_), ¹⁄₁₂ inch, black; on the tips of the stems of field and marsh beans, also on poppy, turnips, lettuce, and on several wild composites and umbellifers. The =Pea Aphis= (_Aphis ulmariæ_), ⅛ to ⅙ of an inch long; green; July to September on peas, chickling peas, and several wild leguminous plants; very destructive. The =Corn Aphis= (_Aphis cerealis_), ¹⁄₁₂ inch, green or reddish brown, also reddish brown with green abdomen; June to August on rye, barley, oats and several grasses; sucks the axis of the ears, and the flower-stalks; as the (black) eggs remain on the stubble during the winter, it is advisable to plough this deeply in immediately after harvest. The =Oat Aphis= (_Aphis avenæ_), ¹⁄₁₂ inch, dark green, speckled with white; on oats and barley, scarcely ever on the ears, but on the leaf-sheaths and the upper sides of the rolled-up leaves. The =Hop Aphis= (_Aphis humuli_), ¹⁄₁₂ inch, green; on the under side of the hop leaves, and, when very abundant, on the scales of the fruit. The =Cabbage Aphis= (_Aphis brassicæ_), ¹⁄₁₂ inch, dark green, speckled with grey; from May to September on all kinds of cabbage, and also on other crucifers.

SEVENTH ORDER: =Physopoda= (BLADDER-FOOTED INSECTS).

Very minute insects, possessing a characteristic jaw apparatus, with which they pierce the outer skin of leaves or the parts of flowers, and suck their juices. The four small wings have long fringes at their edges; the fore wings are tolerably hard. The ends of the feet do not possess claws, but small bladders or suckers. The metamorphosis is incomplete. In some years, one or other of the species may increase to a very large extent, and these minute insects then fly about in swarms, especially on very hot days; and they also wander about in large flocks. If they settle on the face or hands of human beings, they cause a disagreeable and persistent itching, as they continually walk about.

FIG. 109.—Corn Thrips (_Thrips cerealium_).
]

The =Corn Thrips= (_Thrips cerealium_), ¹⁄₁₂ inch. Dark brown to black. Male wingless. Female with small wings bending outwards at their tips (Fig. 109); fore wings horny, hind wings membranous. Larva orange yellow; head, prothorax, and tip of the abdomen, black. After the last moult it becomes yellowish white, and acquires scale-like wings. Hybernates in the adult condition; lays its eggs on various grasses, also on different grain-plants. The larvæ, and, later on, the perfect insects are found in large numbers sucking the ovaries of flowering corn (wheat, rye, barley); as a result of which the ears do not fully develop, but wither away. _Remedy_: Deep ploughing of the stubble, by which the hybernating individuals are destroyed.

The =Elder Thrips= (_Thrips sambuci_) lives in elder, and sometimes also multiplies in very young field beans, the leaves of which blacken and shrivel up in consequence.

The =Flax Thrips= (_Thrips lini_) often injures flax.

EIGHTH ORDER: =Diptera= (FLIES).

Mouth-parts elongated, adapted for sucking or piercing. Fore wings developed, rarely absent. Hind wings absent, as such,—altered into club-like bodies (balancers or halteres) often covered with scales. Metamorphosis complete. Larvæ always legless; most have biting mouth-parts and no distinct head (maggots); the head-bearing dipterous larvæ possess similar mouth-parts. The last become obtectate pupæ (p. 93), while the headless larvæ become pupæ within the larval skin.

Family: =Culicinæ= (_Gnats_).

Slenderly built, with long, thin legs. An elongated piercing proboscis in the female. The male with feebly developed mouth-parts, and feather-like antennæ. Both sexes suck up water and plant juices, and the female blood as well; hence only the latter bites, especially at night. They hybernate in the adult condition in cellars, barns, etc. The female lays 250 to 300 eggs on any floating object in stagnant water (pools, ditches, water-vessels). The larvæ (with large head, well-developed prothorax, and a breathing-tube on the abdomen) live in water, as do the pupæ. Several generations annually; especially in damp summers and districts where the draining of the soil leaves much to be desired. Although sand flies torment our domestic animals more than gnats, yet these also may be very troublesome to them. They principally attack the less hairy parts of the body (inner side of the ears, nose, mouth, corners of the eye, arms, sexual parts). _Remedies_: Thorough draining of the soil. Washing the domestic animals to be protected with a vinegar extract of walnut leaves; rubbing with walnut leaves. Wherever possible, any sores should be covered up, as they attract gnats, sand flies, and flies; or the skin near them may be painted with turpentine or very dilute carbolic acid. This is the less to be neglected, as several kinds of flies eagerly lay their eggs in the sores of domestic animals.

Family: =Gallicolæ= (_Gall Gnats_).

FIG. 110.—The Wheat Midge (_Cecidomyia tritici_), female.
]

Small gnats with large broad wings, much narrowed at the root, rounded at the tip, and generally rough with hairs. Feelers made up of a large number of spherical or cylindrical joints, covered with spreading hairs. Proboscis short, legs long. The female has an ovipositor, with which she inserts eggs in any part of a plant. At this particular spot a luxuriant growth of vegetable tissue takes place later on, of varying extent, and even forming a regular gall. The species of gall gnat are usually brightly coloured, often red or yellow; these colours are lost, however, in dried specimens. The larvæ are spindle-shaped, yellowish white, yellow, or red; they become pupæ either in the soil or within the part of the plant which they inhabit. Several species are destructive to fruit-tree culture or forestry; I mention here only the most destructive kinds which attack cultivated plants.

The =Hessian Fly= (_Cecidomyia destructor_).

FIG. 111.—Plant of Barley, attacked by Hessian Fly. The pupæ at _a_.
]

Female about one-eighth of an inch long, male somewhat smaller. The former velvety black, with black hairs, red belly, and red markings; wings greyish; antennæ one-third the length of the body. Male black, with reddish-yellow hairs, dirty red belly, and red markings. The name “Hessian flies” was given in North America, during last century, because it was believed they were introduced from Germany, in 1778, by Hessian soldiers, in their straw. It is still very destructive in North America, also in Germany, Russia, England, and Scotland. _Habits_: During April or May, on warm still evenings, the female lays her eighty or ninety eggs, singly or in pairs, on the lowest leaves of the still very short haulms of rye, wheat, and barley. Eight days, on an average, after this the maggots, which are at first oblong and spotted with reddish yellow, are hatched, and glide down into the leaf-sheath, where they begin to suck the haulm. They gradually alter their shape, becoming ovoid, and transparent with the exception of the large yellowish white, quite opaque fat body. They soon become pupæ (Fig. 111), which look like grains of linseed, and are found in summer on the haulms of the ripe grain. The presence of the constantly sucking larvæ causes great and injurious distortions of the plant, especially obvious during the flowering time, and for a short time afterwards. The haulm withers, and shrivels at the point where the larvæ are present, _i.e._ above the lowest node, or the lowest but one. At the time when the haulm begins to turn yellow—that is, when the grain begins to ripen,—the larvæ become pupæ; the haulm now easily breaks off at the infected spot; a strong wind or heavy rain throws it to the ground. A badly infested field looks, on this account, as if a herd of cattle had got loose and trodden it all down, or as if the grain had been devastated by hail. Only a few haulms bear ears containing normally developed grains. The flies emerge from the pupæ in August and September, after which the females quickly seek the winter corn, and lay their eggs singly or in pairs on the leaves of the yet young plants. The larvæ creep between the leaf-sheath and the still quite undeveloped haulm, and, in the case of small haulms, a number of larvæ may collect together in the immediate neighbourhood of the root, causing a spherical swelling. In many cases the plant dies if its lower parts are inhabited by many larvæ. Before winter, the larvæ attain their full size, leave the plants, and creep into the soil, where, in the following spring, they become pupæ, from which flies emerge fourteen days later. There are, therefore, two generations annually. The _spreading_ of Hessian flies into regions where they were formerly unknown may be caused by (_a_) straw containing the linseed-like pupæ (straw for paper manufacture, packing, etc.); (_b_) grain, among which are often found pupæ that have fallen out of the haulms among the separated grain. _Remedies_: 1. Sowing the winter grain as late as possible, so that the females of the summer generation when they come out of the pupæ will find no winter-grain-plants in which to lay their eggs. 2. Ploughing up the stubble immediately after harvest, or else burning it, so that the pupæ found above the lower nodes are either deeply buried or else burnt.

The =Scarlet Wheat Midge= (_Cecidomyia equestris_).

Female about ⅛ inch, male ¹⁄₁₂ inch; cherry red, with yellow hairs; back of the thorax dark brown. Antennæ as long as the body in the male, half as long in the female. On the wing from May till June; lays its eggs on the leaves of grain-plants, at the base of the uppermost leaf by preference. The blood-red maggots, when they are hatched, let themselves slide down, and get between the leaf-sheath and haulm. Here they work themselves into the haulm, making a longitudinal groove, the walls of which swell more or less, and the end of which is indicated by an obvious transverse thickening. The leaf-sheath hiding the attacked part of the stem is usually more or less swollen. These gall-like outgrowths take up a great deal of nutritious matter, not only from the affected haulm but also from the plant at large, so that the regions not directly attacked are retarded in their growth. The larvæ are full-grown at harvest time, leave their hiding-places, and let themselves fall to the ground, where the following spring they become pupæ, from which midges quickly emerge. _Remedy_: After a year in which the insect has caused great damage, the fields must be deeply ploughed in order to kill the larvæ, which would otherwise live through the winter.

The =Wheat Midge= (_Cecidomyia tritici_).

FIG. 112.—The Wheat Midge (_Cecidomyia tritici_): LI, larva in the
contracted, LII, the same in the extended condition. B, a wheat
flower: _a__{1} outer, _a__{2} inner glume, _b_, stamens; _c_,
brush-like stigmas; _d_, ovary; _l_, larvæ of the wheat midge. LI
and LII highly, B less highly, magnified.
]