Chapter III: Part 3

Beak conical, thicker and shorter than in the species of the following group. They devour insects and seeds, a few species seeds exclusively. Here belong first the =Titmice= (_Parus_), gipsy migrants which are extremely serviceable both in fruit-tree culture and forestry. Then the =Larks= (especially the =Skylark=, _Alauda arvensis_, a resident), which nest on the ground, eating insects, seeds, and in winter even leaves; they feed their young, however, with insects. They do both good and harm, but the former mostly preponderates. In late summer and autumn, skylarks collect in flocks, and wander here and there for a long time: before this, they travel south; at this time many are caught and eaten. The male skylark sings beautifully, rising meanwhile high in the air. The =Buntings= (_Emberiza_) have a characteristic compressed and pointed beak; they seek their food on the ground in fields and meadows, and on roads. The food consists of grain and insects; but since these birds never take grains from the ear, they only do damage by picking them up at seed-time. They feed their young with insects. The damage is usually very inconsiderable, but, on the other hand, the benefit conferred is slight. (=Yellow Hammer=, _E. citrinella_, a yellow-coloured resident. The =Common Bunting=, _E. miliaria_, a grey-coloured migrant, etc.) In the family of =Finches= a number of species are included which are of small agricultural importance: _e.g._ the =Bullfinch= (_Pyrrhula vulgaris_), specially attacks fruit-tree buds in March; the =Goldfinch= (_Carduelis elegans_); the =Siskin= (_Chrysomitris spinus_); the =Lesser Redpoll= (_Linota linaria_); the =Greenfinch= (_Ligurinus chloris_). A few species, however, must be dealt with more fully, and, first,—

FIG. 37.—Head of Bullfinch.
]

The two =Sparrows=,

_i.e._ the =House Sparrow= (_Passer domestica_) and the =Tree Sparrow= (_P. montana_).

=House Sparrow=: ear region bright grey. A rust-coloured or yellowish streak behind the eye. The whole throat black in the male. Wings with a yellowish white transverse band. =Tree Sparrow=: ear region black. A black streak behind the eye, a white band round the neck, and a black patch on the throat. Wings with two white transverse bands. The two sparrows are very much alike in their habits, but the house sparrow frequents more the neighbourhood of human dwellings, even in large towns. Both sparrows are mainly harmful; where seeds (especially those containing starch, _e.g._ corn) are available, they prefer this kind of food to any other; and, besides this, they chiefly bring up their young on soft unripe grain. Sparrows devour the germinating corn after seed-time, and also pick the grain from the ear, in which process they at the same time do damage by breaking down the haulms so that the grain falls out. They pick the young peas from their pods; devour, too, several juicy tree fruits, _e.g._ cherries and grapes; and destroy young garden seedlings, _e.g._ lettuce, spinach, garden flowers. The house sparrow eats more insects than the tree sparrow (among them—geometer caterpillars, injurious roller caterpillars), but leaves the most noxious kinds untouched. Both sparrows are residents, but in autumn and winter often collect together in large flocks.

The =Linnet= (_Linota cannabina_),

with grey-brown darkly spotted back. Belly whitish, tail black with broad white margins. During summer the top of the head and the breast of the male are of a beautiful red. They are often found together in flocks during September. In spring and summer they chiefly live on oil-containing seeds, and may even do some good by eating the seeds of charlock; usually, however, doing much more harm by devouring the seed of rape, flax, linseed, and hemp.

The =Chaffinch= (_Fringilla cœlebs_).

A white patch on the two outermost tail feathers and the ones next them. Wings with one white and one yellowish transverse band. Male: upper side of head and neck bluish grey, back brown, breast reddish brown. Female: back grey-brown, belly whitish, breast ash-grey. The chaffinch inhabits forests, both those of ordinary foliage trees and those consisting of conifers; it also nests in gardens and plantations. At the beginning of September the males separate from the females, and both sexes collect in large flocks which haunt gardens, avenues, and bushes. In mild winters they remain resident, but travel away if the cold is greater. The chaffinch devours oil-containing seeds by preference, but also eats starchy ones, and seeks its food on the ground. It does a great deal of damage in cornfields by picking the seeds out of the soil after they have been sown; but does not take the grain from the ear. It also eats young seedlings. But valuable services more than counterbalance the harm done. When the chaffinches in autumn fly about in large flocks in the fields, they eat an enormous number of weed seeds. The young are chiefly fed with insects, especially with caterpillars. In the spring, when the seeds have germinated and the young corn is not yet ripe, the chaffinch feeds itself also on insects.

Group: =Subulirostres= (_Awl-beaked Perching Birds_).

Beak slender, awl-shaped, round in transverse section. A fully developed organ of voice. Feed almost exclusively on insects; there are only a few species which occasionally eat seeds. A few of them, however, sometimes devour juicy fruits (cherries, bird-cherries, elder-berries, juniper-berries, grapes). The birds belonging to this group, without exception, feed their young on insects. They are of service; even those species which occasionally do damage are useful on the whole.

There belong to the Subulirostres—

The =Wagtails= (_Motacilla_), _e.g._ the =White Wagtail= (_M. alba_), usually living in the neighbourhood of water, and seeking its insect food in the fields (often behind the plough), and in pastures and gardens.

The lark-coloured =Pipits= (_Anthus_).

The =Hedge Accentor=, or “Sparrow” (_Accentor modularis_),—in garden hedges, and woods, feeding sometimes on seeds.

The following “warblers:” =Nightingale= (_Daulias luscinia_), =Robin= (_Erithacus rubecula_), =Redstart= (_Ruticilla phœnicurus_), the =Lesser Whitethroat= (_Sylvia curruca_), =Garden Warbler= (_S. hortensis_), =Willow Wren= (_S. trochilus_), =Chiffchaff= (_S. rufa_), =Reed Warblers= (_Acrocephalus streperus_ and _A. arundinacea_), etc. The last-named live among reeds and rushes on the banks of fresh waters, and eat insects which do not affect agriculture and forestry; all the other warblers are useful.

Other examples of the Subulirostres are the =Golden-crested Wren= (_Regulus cristatus_), and the =Common Wren= (_Troglodytes parvulus_), which are of service to forestry and fruit-tree culture, but not to agriculture.

FIG. 38.—The Nightingale (_Daulias luscinia_).
]

Most of the native thrush-like birds (_Turdus_), _e.g._ the =Blackbird= (_T. merula_), the =Missel Thrush= (_T. viscivorus_), the =Fieldfare= (_T. pilaris_), the =Redwing= (_T. iliacus_), and the =Song Thrush= (_T. musicus_), assist the farmer by devouring noxious insects and snails; but several of them occasionally do damage by poaching on cherries, grapes, currants, etc. Some of them (_e.g._ the Song Thrush and Blackbird) breed in almost all parts of Britain, others come here only in autumn or winter.

ORDER: =Gyrantes= (DOVES).

Body strongly built, somewhat thick-set. Wings long and pointed. Beak weak, with a cere at its base; nostrils covered by gristly scales. Toes: three forwardly and one backwardly directed, free, _i.e._ without a web (as in poultry). The young are at first blind and naked. They are at first fed with a cheesy secretion of the glands of the crop; later, with grain softened in the crop. Doves always live in pairs. Nests careless, flat, of loosely arranged twigs; situated on tree-branches, rocks, and large buildings. Doves breed twice or thrice a year, laying two longish, shining white eggs.

Native British forms:—

FIG. 39.—The Wood Pigeon (_Columba palumbus_).
]

1. =Wood Pigeon= (_Columba palumbus_, Fig. 39), from April to September scattered about in the woods, but after the breeding season wander about in flocks, and in winter travel further south, although many remain. It nests on horizontal branches, and feeds on seeds of fir and pine, acorns, beechnuts, also grain, peas, vetches, rape-seed,—but seeds of many weeds as well (_e.g._ those of charlock, vetchling, spurry, cleavers). When the earth is covered with snow it often eats cabbage and the leaves of winter rape, but is also of some service.

2. The =Turtle Dove= (_C. turtur_) occurs on the edges of woods, especially those consisting of coniferous trees. Nests in the trees. For _food_, _use_, and _harm_, cp. the preceding species. Steals buckwheat grains from the fields.

3. The =Rock Pigeon= (_C. livia_) is the original stock of our races of domestic pigeons. It nests, as a resident, in the Mediterranean countries; as a migrant, on the rocky parts of the coasts of Great Britain and the Orkneys, Shetlands, and Faroe Islands.

ORDER: =Rasores= (POULTRY).

Body strong, thick-set. Head small, often with naked, brightly coloured patches, with fleshy combs or with a crest of feathers. Tip of the upper beak bends over that of the lower one. No cere (cp. Doves). Wings short, rounded; flight heavy. Feet strong. Hinder toe small and usually attached to the tarsus higher up than the front toes. Claws blunt. A small web at the bases of the toes. The male of several species bears a spur on the tarsus. Birds of this order usually keep on the ground, scraping it in search of their food, which consists of seeds, berries, the green parts of plants, insects, worms, and snails. Young precocious (p. 51). Several domestic birds belong to the Rasores: pheasants, the various races of fowls, pea-fowls, guinea-fowls, turkeys.

The species living wild in Britain are game-birds. They are—the =Capercailzie= (_Tetrao urogallus_, Fig. 40), =Black Game= (_T. tetrix_), =Partridge= (_Perdix cinerea_), =Quail= (_P. coturnix_); none of them are particularly harmful or useful to agriculture.

The =Pheasant= (_Phasianus colchicus_, Fig. 41) was originally a native of the Caucasus, and shores of the Caspian Sea and Sea of Aral; it occurs wild in Central Europe. Pheasants are troublesome to the farmer, both by devouring the newly sown seed and by scratching up the fields.

FIG. 40.—Male and Female Capercailzie (_Tetrao urogallus_).
]

ORDER: =Grallatores= (WADING-BIRDS).

The species here included differ very much among themselves; but all seek their food, which is almost exclusively of animal nature, at the water-edge (rivers, brooks, lakes, ditches, canals, seashore) or in damp places (damp meadows and ploughed fields, moors, swamps). They are, therefore, adapted to wading, and for this purpose have a long featherless tarsus, while the lower half of the long shank is quite bare and covered with horny scales. In flight the wading-birds do not draw their legs up to their body, as is the case with the birds already spoken of, but stretch them out behind to their full length. Monogamous. Young precocious (p. 51), except in storks and herons when they are nestlings. The shore-dwellers eat fish, bivalve molluscs, etc.; only those species living on damp meadows and fields are of use to agriculturists, by devouring insects, snails, and worms. These are indicated by the letter u in the following list of the commonest native kinds:—

FIG. 41.—The Pheasant (_Phasianus colchicus_).
]

=Coot= (_Fulica atra_); =Water Hen= (_Gallinula chloropus_); =Corn Crake= (_Crex pratensis_, u); =Plovers= (_Charadrius_, u); =Pewit= or =Lapwing= (_Vanellus cristatus_, u); the =Snipes= (_Scolopax_); the =Curlews= (_Numenius_, u); the =Stints= (_Tringa_); the =Godwit= (_Limosa ægocephala_, u); the =Sandpipers= (_Totanus_, u); the =Heron= (_Ardea cinerea_).

FIG. 42.—The Woodcock (_Scolopax rusticola_).
]

ORDER: =Natatores= (SWIMMING-BIRDS).

These birds are distinguished by their swimming powers and corresponding organization. Legs usually set on far back, shorter than the body. The feet in particular are adapted for swimming. In some swimming-birds each of the forwardly directed toes has a webbed margin (“split swimming feet,” Fig. 43); in others, the three front toes are all united by a web (Fig. 44), while the hind toe is either small or wanting (“swimming feet”); lastly, there are some in which all the toes are forwardly directed and united by a common web (“oar-feet”). The plumage of swimming-birds is compact, and always kept greasy by the secretion of the oil-gland. I shall speak of two families only.

Family: =Lamellirostra= (_Ducks_).

FIG. 43.—Crested and Little Grebes (_Podiceps cristatus_ and _minor_).
]

The inner margin of the beak is covered by skin, thrown into transverse ridges or tooth-like projections. Swimming feet (Fig. 44). Tolerably long wings; remarkable powers of flight. Feathers soft. These birds mostly affect shallow fresh water, in which they get their food by grubbing in the mud, the soft skin of the beak serving as an organ of touch. Polygamous. Young precocious (p. 51).

Here belong—the long-necked =Swans= (_Cygnus_) and the thick short-necked =Geese= (_Anser_), in which the beak is higher than broad at its base; the =Swimming Ducks= (_Anas_) with broader beaks, the =Diving Ducks= (_Fuligula_), and =Goosanders= (_Mergus_) with a broad hanging web to the hind toe. None of these birds are useful, while wild geese and ducks are harmful.

FIG. 44.—Goose (_Anser cinereus_).
]

Three species of wild =Geese= (=Grey Goose= = _Anser cinereus_, =Bean Goose= = _A. segetum_, =White-fronted Goose= = _A. albifrons_) chiefly breed in Eastern or Northern Europe, and only come to Britain in autumn or winter, flying about in flocks. They eat the grass in low-lying meadows, and even pull it up by the roots; in the cultivated fields they devour winter corn and winter rape, and tread down more with their clumsy feet than they eat. They are also harmful to vegetable growth, owing to the very caustic nature of their dung, which is often deposited in large quantities in one place. In regions where they breed they also devour both ripe and unripe grain. Where they only occur in autumn, they scrape potatoes, turnips, and carrots out of the ground in order to eat them. Flocks of geese fly in a slanting line or in the form of a ploughshare.

Among _Swimming Ducks_ damage is only done by the =Wild Duck= (_Anas boschas_). It breeds wherever there are fresh waters. Nests amongst grasses or swamp-plants, or in a tree. The wild ducks remain the whole winter as long as the waters are not frozen, otherwise they go off for a short time to the south. Food: the tops of stems, buds, leaves of various water-plants, also barley, oats, and other grain; water-insects, fish, and fish-spawn. These ducks also do damage in cornfields by treading down and cracking the plants.

Family: =Longipennes= (_Gulls_).

Usually swimming feet. Legs tolerably long, adapted for wading (Fig. 45). Wings long, pointed. Beak laterally compressed. Young nestlings (p. 51). Breed in larger or smaller flocks, usually on the coast, occasionally on the margin of fresh waters. They chiefly feed on fish, worms, molluscs, and crustacea; sometimes, in the case of a few species, on young birds and eggs, as well as mice and other small mammals. Gulls are usually of no importance in agriculture; but the =Black-headed Gull= (_Larus ridibundus_), which breeds on the banks of lakes and rivers, devours many cockchafers and other noxious insects. The =Herring Gull= (Fig. 45), =Kittiwake= (_Larus argentatus_ and _L. tridactylus_), and a few other species, which breed on the coast, sometimes show themselves inland, especially in stormy weather; they then pursue field-voles, and catch many injurious insects.

Besides the true =Gulls= (_Larus_), I will only mention the =Sea Swallows= (_Sterna_), with forked tails.

FIG. 45.—Herring Gull (_Larus argentatus_).
]

CLASS III.: =REPTILIA= (REPTILES).

Cold-blooded Vertebrates (p. 19). The heart has the same structure as in Mammals and Birds, but the left and right ventricles are usually only incompletely divided from one another (p. 20). The body is invested with horny scales or with bony plates covered by a horny layer. Reptiles are very unlike Birds in appearance, but present many essential points of resemblance to them in their skeleton; indeed, during earlier geological times, there were transitional forms between the two classes. The structure of the reptile egg, too, is very similar to that of the bird’s egg; but the first has no lime-salts deposited in its shell. The egg is not hatched out by the animal itself, but exposed to the heat of the sun or to the warmth developed by decaying vegetable matter. Several reptiles (adder, for example) keep their eggs in their bodies till the young escape. Reptiles have either no limbs (snakes, a few lizards), or, at any rate, the limbs are not well developed, and are so placed that the body does not rest upon them, but is slung between them.

FIG. 46.—Common Lizard (_Lacerta agilis_); 2, head of the same from
below; 3, tongue.
]

The Reptilia are divided into the Orders of =Crocodilia= (Crocodiles), =Chelonia= (Turtles and Tortoises), =Lacertilia= (Lizards), =Ophidia= (Snakes).

FIG. 47.—The Adder (_Pelias berus_).
]

Our native reptiles have no agricultural importance. I will, however, briefly mention the =Adder= (_Pelias berus_, Fig. 47), as it is dangerous to man. Head broad; tail much smaller than the hinder end of the body. Colour greenish grey or brownish. A black zigzag band runs along the dorsal side of the body. Length about twenty inches. The two hook-shaped poison-fangs are found in the front of the upper jaw; opening the mouth widely causes them to be erected. They are traversed by poison-canals through which the poison flows immediately into the two bloodless wounds. The adder lives in woods and on mountain slopes, where it devours mice. The poison has a decomposing action on the blood; it causes fever, and swelling of the part bitten, as well as sometimes of the neighbouring parts. The bite may be fatal. Alcohol is spoken of very highly as a remedy.

FIG. 48.—The Grass Snake (_Tropidonotus natrix_).
]

FIG. 49.—Blindworm (_Anguis fragilis_).
]

The native =Ringed Snake= (_Tropidonotus natrix_, Fig. 48), three feet long, is bluish with belly flecked with black and white; a yellow and a black band on the neck. It is fond of going into the water, and eats frogs, newts, and insects. The =Smooth Snake= (_Coronella lævis_), two feet long, is brown, with black patches on the back, which, however, do not form a continuous band. Head dark velvety black. Devours lizards and blindworms. The =Blindworm= (_Anguis fragilis_) is indeed snake-like, or rather worm-like (Fig. 49), but nevertheless belongs to the lizards, with which its internal structure agrees.

CLASS IV.: =AMPHIBIA= (AMPHIBIANS).

FIG. 50.—Great Crested Newt (_Triton cristatus_); male above, female
below.
]

Cold-blooded Vertebrates (p. 19). The heart has only one ventricle and two auricles (cp. p. 21). The skin is naked, damp, usually slippery and smooth; it helps in respiration. Although several Amphibians resemble various Reptiles in outward appearance (Newt and Lizard, Figs. 50 and 46), the structure of the skeleton is quite different. Upon the whole, Amphibians resemble fishes more closely, and they breathe by gills when they are young, which strengthens the agreement. They undergo a metamorphosis. The just-hatched young at first hold fast by suction to the jelly of the spawn; they have external gills. They quickly develop a membranous margin to the body, especially round the tail, which consequently forms a sort of oar. Meanwhile internal gills develop, and the external ones disappear. The larvæ are now fish-like (“tadpoles”). The limbs quickly grow out, the lungs develop, the tail shrivels up, and the animal leaves the water. Even the adult, however, lives among damp surroundings. In the adult state the Amphibians feed on insects, worms, and snails; many species are exceedingly useful owing to this.

Amphibians are divided into two orders, the _Urodela_ (Newts, etc.) and the _Anura_ (Frogs and Toads). To the first belong the =Great Crested Newt= (_Triton cristatus_) and the =Common Newt= (_Lissotriton tæniatus_). Examples of the Anura are the =Edible Frog= (_Rana esculenta_), the brownish =Common Frog= (_R. temporaria_, Fig. 51), the =Common Toad= (_Bufo vulgaris_), and the =Natterjack= (_B. calamita_, Fig. 52).

FIG. 51.—Common Frog (_Rana temporaria_).
]

Both frogs and toads do good by devouring many noxious insects, and also, in particular, snails. Toads are often kept in greenhouses for this purpose; and in the research garden attached to the Rouen entomological laboratory the snails were entirely exterminated in 1891, as a result of introducing a hundred toads and ninety frogs.

FIG. 52.—Natterjack (_Bufo calamita_).
]

CLASS V.: =PISCES= (FISHES).

Cold-blooded Vertebrates (p. 19), which breathe by gills during their whole life. The heart consists only of a single ventricle and a single auricle (p. 18). The head passes immediately into the body without any intervening neck. Fishes move chiefly by means of the tail, at the end of which there is a tail-fin. This and the dorsal and anal fins lie in the median plane of the fish, while the pectoral fins, which are attached to the skull in bony fishes, and also the ventral fins, are paired structures more or less comparable to the fore and hind limbs of higher vertebrates. The skeleton of most fishes (pike, perch, carp, eel, plaice) is bony; but in a few subdivisions of fishes (sharks, skates, sturgeons, lampreys) it is cartilaginous. The skin is usually covered with thin translucent scales; but there are fishes with a smooth skin (lampreys), with prickle-like dermal ossifications (sharks), and with rhomboidal bony plates (sturgeons). As Fishes are without exception aquatic, there is no need for me to treat more specially of them here.

FIG. 53.—The Perch (_Perca fluviatilis_).
]

Second Sub-Kingdom: ARTHROPODA (JOINTED-LIMBED ANIMALS).

FIG. 54.—Wood-borer (_Sirex_); 1, larva; 2, adult insect.
]

FIG. 55.—The Large Centipede (_Scolopendra morsitans_).
]

FIG. 56.—Ground Beetle, with nervous system drawn in white.
]

The body of an Arthropod is bilaterally symmetrical (cp. p. 16), and consists of a number of joints (Fig. 55), not equally numerous in all members of the sub-kingdom. These joints or segments lie one behind the other, and are at first alike; but as in the course of further development they become adapted to various functions, the difference between them becomes greater. Compare the Wood-borer represented in Fig. 54, 2, with the young form of the same animal (Fig. 54, 1). The segments often fuse together, which brings about the formation of a smaller number of subdivisions to the body; or even all the segments may become united (mites). In the last case the Arthropod characters are only to be seen in the jointing of the limbs. Segmented animals (_e.g._ the common earthworm) are also found among the worms (Sub-kingdom III. of the Animal Kingdom); but these worms have either no limbs, or only small unjointed foot-stumps, never jointed limbs as in the Arthropods. These last are limbless or with unjointed foot-stumps only when young; when adult they always have jointed limbs. The head of Arthropods bears several successive pairs of jaws, which move to and fro from one side towards the other. The covering of the body consists of hard protective pieces; it is only in the young condition that the skin of several species is soft. Arthropods have no internal skeleton; the muscles are attached to the skin. The central part of the nervous system (p. 10), which consists in Vertebrates of brain and spinal cord, lies in Arthropods almost entirely on the ventral side. In the head is situated the cerebral ganglion, a large nervous mass resting on the gullet, and giving off nerves to the eyes and feelers. Besides this, there is a ventral nervecord on the ventral side of the animal, running below the gut, and made up of several pairs of ganglia, united with one another by means of nerve fibres. The ganglia of the ventral cord send their nerves to the jaws, limbs, muscles, viscera, etc. The cerebral ganglion is connected with the first ventral ganglion by means of a cord on each side of the gullet (Fig. 56), so that a ring-like structure is formed. The breathing organs are gills in some Arthropods (the Crustacea, _e.g._ crayfish, crabs); insects and centipedes breathe by air-tubes or tracheæ, while the respiratory organs of spider-like animals, when these do not breathe entirely by means of the skin, are more or less strongly modified tracheæ. The structure of the tracheal system is generally as follows: on each side of the body there is a row of breathing-holes, or stigmata, through which the air can enter the tracheæ; these are very much branched, so that they finally become very fine tubes investing the various organs, which in this way obtain the requisite amount of oxygen. The stigmata on one side of a caterpillar are clearly shown in Fig. 60, and those of a hornet larva in Fig. 61.

Four classes belong to this sub-kingdom: Insecta (Insects), Myriapoda (centipedes, etc.), Arachnoidea (spiders, scorpions, etc.), Crustacea (crayfish, crabs, lobsters, etc.).

CLASS I.: =INSECTA= (INSECTS).

FIG. 57.—A Grasshopper, with the different regions of the body
separated from one another. A, head; B, thorax: _I._, prothorax;
_II._, mesothorax; _III._, metathorax; C, abdomen; _a_, antennæ;
_b_, eyes; _c_, _d_, _e_, legs; _f_, _g_, wings; _p_, shank; _q_,
foot.
]

Breathe by tracheæ (cp. p. 84). The segments fuse into three body regions (Fig. 57). These are—(1) the _Head_, bearing the eyes, feelers (antennæ), and jaws; (2) the _Thorax_, composed of three fused segments, of which the first (prothorax) bears a pair of legs, while the second (mesothorax) and third (metathorax) not only bear a pair of legs each, but also sometimes a pair of wings in addition; (3) the _Abdomen_, which possesses no limbs, and of which the number of segments is not always the same. These three regions of the body perform different functions; the head is concerned with sensation and the taking up of food, the thorax with movement, while the abdomen contains the organs of digestion and reproduction. I will now deal somewhat more fully with the different body regions of an insect.

_Head._—Almost all insects have in the adult state a compound eye, _i.e._ an eye made up of a large number (up to ten thousand) of smaller eyes. In many insects one finds in addition to this a few simple eyes on the top of the head. The feelers are very unlike in different insects; they serve as organs of touch, and perhaps also help some other sense. The mouth-parts consist of three pairs of jaws, of which the first (the mandibles) and the second pair (maxillæ) are freely movable from side to side, while the third consists of two jaws immovably fused together (lower lip, or labium). A downward projection of the skin of the head (the upper lip, or labrum) overhangs the three pairs of jaws (Fig. 58). In insects which feed on solid matters, tearing or chewing them, the jaws are short and sharp-edged (biting mouth-parts); in those which take up fluid food (blood, the juices of plants, etc.) they are elongated, and adapted for licking, sucking, or piercing.

FIG. 58.—Head and Mouth-parts of a Ground Beetle, enlarged four times.
A, from above; B, from below. _a_, labrum; _b_, mandible; _f_,
maxilla with palpi (_g_); _c_, labium with palp (_e_).
]

_Thorax._—The names of the parts of the legs are for the most part those used in the case of mammalian limbs; though the similarity between the limbs of Mammals and Insects is quite superficial. The following parts are distinguished in the leg of an insect: (1) the generally spherical hip (_coxa_) (Fig. 59, _a_); (2) the very short _trochanter_ (_b_); (3) the elongated thigh (_femur_) (_c_); (4) the shank (_tibia_) provided with movable spines at its tip (_d_); (5) the three- to five-jointed foot (_tarsus_) (_e_), whose last joint ends in claws, and often also in flap-like outgrowths. The _Wings_ are expansions of the skin, which consist of two layers. There are tracheæ between the upper and lower lamellæ. At first (in the pupa) the wings are folded up; but the forcing of air into the tracheæ quickly causes them to unfold. A firm substance is now deposited in the larger tracheæ, which are thus converted into veins or ribs giving support to the wings. In beetles the fore wings are quite hard and horny, and serve for protecting the delicate hind wings and soft back rather than for flight; they are therefore named “wing-covers” (_elytra_). In many insects the fore wings (wasps) or the hind wings (beetles, grasshoppers) are folded when at rest.

FIG. 59.—Leg of a Ground Beetle (× 2).
]

FIG. 60.—Silkworm Moth (_Bombyx mori_). Female moth, caterpillar, pupa
and cocoon.
]

The _abdomen_ only bears organs of movement in caterpillars (Fig. 60) and a few other insects in the young condition, and in these cases they are not jointed like the true legs or “thoracic feet,” but unjointed pro-legs or “abdominal feet.” In the adult insect the abdomen may have thread-like (mole-cricket) or pincer-like (earwig) appendages; or appendages used in egg-laying (ovipositors, _e.g._ Locust).

Most insects have great powers of reproduction. A few bring forth living young, but most insects lay eggs. It is only in a few (_e.g._ lice) that animals exactly like their parents are hatched from the eggs; the large majority of insects pass through a _change_, or _metamorphosis_.

A distinction is drawn between _complete_ and _incomplete_ metamorphosis. It is said to be complete when the insect passes through a stage in which it takes up no food, and, as a rule, moves but little. In this condition of almost complete rest the insect is called a “pupa” (Figs. 60, 61, 65). The metamorphosis is called incomplete when the insect does not pass through a pupa stage, and therefore feeds and moves during all the periods of its development, merely altering its form somewhat during its various moults (Fig. 62).

FIG. 61.—The Hornet (_Vespa crabro_), with larva and pupa.
]

The word “moult” must here be explained. The covering of the skin of Arthropods consists of hard parts incapable of being stretched. At the end of a definite period of time this firm covering is stripped off and replaced by a new investment, soft at first, but afterwards becoming hard. In this way growth can be effected in spite of the hard integument. Everyone must have noticed at some time or other the moulting of caterpillars.

FIG. 62.—The Migratory Grasshopper (_Acrydium migratorium_). Larva and
adult female.
]

FIG. 63.—Looper Caterpillar.
]

FIG. 64.—False Caterpillar.
]

In insects with incomplete metamorphosis the form of the animal alters a little at every moult, becoming more and more like that of the adult insect. In the last moult but one small imperfect wings appear (Fig. 62, _left_), and fully developed wings are only present after the last moult. The ovipositors of female insects, in those cases where the metamorphosis is incomplete, first appear as fully developed organs in the perfect condition of the animal, but begin to develop in the preceding stage. In cases of this kind of metamorphosis the young insect (“larva”) closely resembles the adult in form even in the first stage of development. In insects undergoing complete metamorphosis the difference between larva and adult insect (imago) is much greater (Figs. 60, 61, 65).

FIG. 65.—The Common Cockchafer (_Melolontha vulgaris_). Larva, pupa,
female flying, and male creeping out of the earth.
]

The time passed in the pupa state by insects with complete metamorphosis is by no means always of the same length. For example, there are two generations annually of the cabbage white butterfly; one lives through the winter in the pupa state, the pupæ of the other are found in summer. So that while an insect of the winter generation lives about half a year in the pupa state, this condition lasts only about a month in the summer generation. A higher temperature hastens the development.

Although the insect in the pupa state takes no food, it nevertheless breathes, and therefore continually uses up body substance. This using up only takes place to a small extent however, since the animal moves but little. From whence, then, does the pupa get the material to cover the loss of body substance? In the larval condition the insect takes far more food than it requires for the development of its body, and from this excess it builds up reserve stuffs, which are deposited in the so-called “fat-bodies” of the larva. These reserve materials are re-absorbed during the pupa state, and serve to maintain the breathing. Consequently a pupa that has just been formed moves more than another one just about to become a butterfly.

FIG. 66.—Larva of a Weevil.
]

FIG. 67.—A Hover Fly (_Syrphus pyrasti_). Fly, maggot, and pupa case.
]

The larvæ and pupæ of the different kinds of insects which undergo a complete metamorphosis have not the same shape of body. Among the larvæ may be distinguished _caterpillars_, _grubs_, and _maggots_. The _caterpillars_ (Fig. 60) have a clearly marked head with hard covering, three pairs of jointed thoracic legs, and a varying number of unjointed pro-legs. They are usually variegated or green in colour, and are divided into _true caterpillars_ and _false caterpillars_ (Figs. 60, 63, and 64). The first, after the resting pupa stage, become butterflies or moths; the latter saw-flies. The true caterpillars have two to five pairs of pro-legs, the false caterpillars six to eight pairs. Reckoning in the thoracic legs, therefore, the true caterpillars have altogether five to eight, the false caterpillars nine to eleven pairs. The head of the latter is more rounded, while that of the former is more flattened. The way in which caterpillars walk depends upon the number of their legs. If this is fairly large so that most of the segments of the body are provided with legs, the whole body remains tolerably extended during progression. But if the number is small—as in the looper caterpillars, where there are three pairs of thoracic legs at the anterior end, and at the posterior end only a terminal pair of legs (the caudal pro-legs) and another pair in front of them—the middle legless region is strongly bent during locomotion (Fig. 63). Hence the name “looper.” The loopers often bend their bodies in a characteristic way. When at rest the hinder part is coiled up spirally; but as soon as the animals are alarmed they throw the hinder part of the body upwards and forwards and even over the head. The _grubs_ (Figs. 66 and 69, _left_) have indeed, like the caterpillars, a clearly visible hard head, but no characteristic abdominal legs, or at most a pair of sucker feet at the end of the body (wireworms). Thoracic legs are present in several grubs (cockchafer larvæ, wireworms, leaf beetles); in others (larvæ of weevils and fleas) they are entirely absent. _Maggots_ are those entirely footless insect larvæ which do not possess a head clearly marked off from the rest of the body, and the head-end of which is only to be recognized by the presence of the mouth and mouth-parts. _Pupæ_ are enclosed in a case which either only faintly indicates the outline of the various parts of the adult insect, or else closely surrounds every part of the body—wings, legs, antennæ, and even the mouth-parts and eyes. Pupæ of the first kind are termed _obtectate_ (Fig. 60); those of the second, _free_ (Figs. 61, 65).

Many pupæ are _naked_, others are surrounded by a web (cocoon) spun by the larva (Fig. 60). There are also pupæ distinguished by the peculiarity that when the insect has lived through the maggot-stage it does not strip off its integument, but turns into a pupa inside the shrivelled maggot-skin, from which the perfect insect later on breaks out (Fig. 67).

The class of insects can be divided into eleven orders: (1) _Coleoptera_ (Beetles); (2) _Orthoptera_ (Grasshoppers, Locusts); (3) _Neuroptera_ (Dragon-flies); (4) _Hymenoptera_ (Bees, Ants, Saw-flies); (5) _Lepidoptera_ (Butterflies and Moths); (6) _Hemiptera_ (Aphides, Bugs); (7) _Physopoda_ (Thrips); (8) _Diptera_ (Flies with two wings); (9) _Aphaniptera_ (Fleas); (10) _Pediculina_ (Lice); (11) _Collembola_ (Spring-tails and Tassel-tails).

ORDER I.: =Coleoptera= (BEETLES).

Beetles (Fig. 65) are insects with biting mouth-parts, and strongly developed prothorax united with the mesothorax so as to permit free movement. The fore wings are in the form of hard covers, leaving exposed only the head, neck-shield (_i.e._ the dorsal side of the prothorax), a three-cornered bit of the mesothorax (_scutellum_), and sometimes the tip of the abdomen. Flight is effected by the hind wings alone, which in a state of rest are drawn back under the wing-covers. The metamorphosis is complete; the larvæ are legless, or with thoracic legs only, and have a hard head with biting mouth-parts; change into free pupæ (p. 93).

Family: =Carabidæ= (_Ground Beetles_).

Usually elongated, slender; with long slender legs, five-jointed tarsi, eleven-jointed antennæ, powerful jaws (Figs. 68, 69). Run rapidly; usually keep on the ground; hide themselves during the day, but are very active at night; with very few exceptions feed entirely on other insects; when touched squirt an acrid stinking fluid out of the abdomen. Larvæ longish, six-legged, with short antennæ and sharp jaws, with a few exceptions live exclusively on other insects and lower animals.

Several species are of service, both in the adult and larval conditions, since they destroy injurious insects, _e.g._ surface caterpillars, wireworms, cockchafers, grubs, crane-fly larvæ. The following do good in cultivated fields: =Golden Ground Beetle= (_Carabus auratus_), =Garden Ground Beetle= (_C. hortensis_), =Granulated Ground Beetle= (_C. granulatus_), =Cross-barred Ground Beetle= (_C. cancellatus_), =Field Ground Beetle= (_C. nemoralis_), =Large-headed Ground Beetle= (_Cephalotes vulgaris_), species of _Harpalus_, _Pterostichus_, etc.

FIG. 68.—A Ground Beetle (_Carabus auronitens_).
]

FIG. 69.—Corn Ground Beetle (_Zabrus gibbus_) and larva.
]

The only destructive form is the =Corn Ground Beetle= (_Zabrus gibbus_, Fig. 69); short, thick-set; back black; belly, legs, and antennæ dark brown. Larva cylindrical, slightly hairy, brown, with yellowish white belly; head broad and flattened, black. The beetles (June, July) usually remain hidden in the soil during the day, climbing up the stalks of barley, wheat, and rye during the evening and in dull weather, and eating the grain in the ear. The larvæ remain during the day in vertical holes which they dig out; but at night and during dull weather they devour the overground parts of the grain-plants mentioned above, especially the hearts of young plants. They are destructive both in autumn and spring, damaging winter and summer grain. The larval condition is maintained for three years, the animal then turning into a pupa during July. Its ravages are limited to special years. _Remedy_: Sowing oats, peas, or vetches, or planting potatoes in fields infested by the beetles or their larvæ; collecting the beetles in the evening when they are in the ears.

Family: =Staphylinidæ= (_Rove Beetles_).

FIG. 70.—Rove Beetle (_Staphylinus erythropterus_).
]

FIG. 71.—The Black Burying Beetle (_Silpha atrata_) and larva.
]

Usually elongated, small (Fig. 70). The short truncated wing-covers leave the whole of the abdomen exposed. The rove beetles resemble the earwigs in their appearance and in a way they have of frequently lifting up the hinder end of the body and turning it forwards. Tarsi five-jointed, jaws strongly developed. The six-legged larvæ resemble those of the ground beetles, but have a relatively large head. The beetles live through the winter; the metamorphosis takes place in autumn. Live on the ground under fallen leaves, also under the bark of trees; in carcases. Some chiefly eat insects living in the soil and noxious insects; others, dung and decomposing matter. (Species of _Staphylinus_, and of _Ocypus_, e.g. _O. olens_, the =Devil’s Coach Horse=.) Several are of service. A few devour the parts of plants. _Anthobium torquatum_ is found in large numbers in the flowers of rape, devouring the petals, stamens, and pollen.

Family: =Silphidæ= (_Burying_, or _Sexton Beetles_).

The antennæ either thicken gradually or have only the end-joints larger; body flat; head projecting; tarsi five-jointed. The burying beetles and their larvæ feed on dead animals. A few (sp. of _Necrophorus_) bury the whole animal in the earth, and lay their eggs in it. Failing carrion, some of them can live on vegetable food; these sometimes do harm. Others prefer living insects and snails. They are of service in the economy of nature by doing away with stinking bodies. The following are sometimes harmful: =Black Burying Beetle= (_Silpha atrata_, Fig. 71), the larvæ of which often do much damage in fields of beetroot; _Silpha opaca_ (=Beet Carrion Beetle=), and _S. reticulata_, which, in the adult condition, may do harm to several kinds of plants. Remedies need not be considered, as it is only rarely they increase so largely as to make the supply of carrion insufficient, and consequently attack plants.

Family: =Nitidulidæ= (_Shine Beetles_).

Small. Antennæ club-shaped, eleven-jointed. Tarsi five-jointed. A few species live on carrion and on fungi, others under the bark of trees, a few in flowers. To these last belongs the =Turnip Flower Beetle= (_Meligethes æneus_); somewhat convex, elongated oval; shining metallic greenish black, finely dotted. Occurs in the inflorescences of turnip, rape, and allied species; also in the flowers of mustard, charlock, and similar crucifers, and species of buttercup (_Ranunculus_). At the beginning of spring, the turnip-flower beetle bores into the buds of turnip, rape, etc., and, later on, attacks the flowers. It perforates the petals, devours the stamens and pollen, and, lastly, the pistil. The infested flowers wither. Three to four beetles are often found in a single flower. The female soon lays her eggs, separately, in the ovary of the flower. One to two weeks later the larvæ may be found in the flowers, one or more in each. The larvæ, one-fiftieth of an inch long to begin with, are, when ready to become pupæ, about one-fifth of an inch long, cylindrical, yellowish white with blackish brown head; they have three pairs of short thoracic legs, as well as a pair of caudal pro-legs. Each segment of the body has two dark blotches on its upper side. On an average, the larvæ reach their full size in four to five weeks. They are first found at the bottom of the flower, where they gnaw the stamens and ovary. They then wander from flower to flower, until ready to become pupæ. If there are no more flowers in the neighbourhood they attack the developing pods, first gnaw the green husk, then bore through it and devour the young seeds. Become pupæ in the soil. The beetle emerges after a fourteen days’ pupa rest. At least two, usually three, sometimes four generations. _Remedy_: Rooting out charlock and the species of buttercup. Selection of strongly growing varieties of turnip, rape, etc., which blossom late (and therefore soon finish blooming). Drill-culture.

Family: =Cryptophagidæ= (_Secret_-_eating Beetles_).

Very minute. Antennæ composed of eleven joints, of which the three last form a club. Legs wide apart; tarsi five-jointed. Live in flowers, fungi, dead parts of plants, under bark, in the earth, in humblebees’ and ants’ nests, etc. The =Beet Beetle= (_Atomaria linearis_) is harmful: longish, egg-shaped, strongly convex; neck-shield as long as broad. Brownish black or dark brown. In fields where beet is cultivated for several years in succession, the beetles often increase in a prodigious way. They attack the seedlings, and devour the base of the stalk just below the surface of the soil, sometimes biting it half through. The attacked seedlings often die even before the cotyledons appear above the surface of the soil. Looking, therefore, in spring at fields infested by the beet beetle, the seedlings will appear quite normally developed in some few places, while in some other places there may be no plants at all: in many spots, again, small plants will be seen bearing only seed-leaves, withered and yellow. These cannot be pulled out of the ground, for they break off at the place gnawed by the beetle. It is often necessary to give two or three successive sowings, as the young crop is attacked again and again. The larva of the beet beetle is still unknown, though this undoubtedly develops in the beet-fields. _Remedy_: Suitable rotation. When the conditions will not permit this, the seed must be sown thickly, so that as many seedlings as possible may remain sound, should the beetles exert their destructive influence in the spring.

Family: =Lamellicornia= (_Chafers_).

FIG. 72.—_a_, Antennæ of male; _b_, of female Cockchafer.
]

Body strong, stout (Fig. 65). The first joints of the antennæ have the usual shape; the last, three to seven, are very short, but broadened out on the inner side into leaf-like appendages, so that the end of the antennæ is fan-shaped (Fig. 72). The little leaves are laid together when at rest, so as to form a club-shaped thickened end; in flight, and when the attention of the beetle is excited, they are spread out like a fan. Legs strong; feet five-jointed. Flight rapid, somewhat awkward. Larvæ thick; body cylindrical, but curved; head hard, brown; rest of the body thin-skinned and yellowish white. The first three segments of the body bear legs. The curved larvæ can move about in the soil, but not on the surface. The beetles and larvæ devour vegetable substances; a comparatively small number of species feed on dung.

FIG. 73.—_a_, abdomen of Common; _b_, of Horse-chestnut Cockchafer.
]

The =Common Cockchafer= (_Melolontha vulgaris_) will serve as a type of the lamellicorns (Fig. 65). The last segment of the body forms a gradually tapering process. The club of the antennæ with seven large leaflets in the male, and six smaller leaflets in the female (Fig. 72). Head, neck-shield, entire ventral surface, and legs, black; although these parts, with the exception of the head, may be reddish brown. Many specimens are thickly clothed with numerous white hairs; others are almost hairless. The beetles usually appear during May, but sometimes by mid April, and sometimes not till the beginning of June. In the evening they leave the soil and seek the neighbouring trees. They devour the leaves and especially the buds of oak, horse-chestnut, beech, poplar, willow, cherry, and other forest and fruit trees, but spare the lime and generally the morel cherry. Of coniferous trees it only devours the needles of larch and the young shoots of pine. Among cabbage-like plants it only devours rape. In “chafer years” the cockchafer becomes a veritable scourge to the farmer. For the purpose of laying her eggs (about forty in number), the female selects by preference a fertile soil rich in humus, but will also put up with a dry sandy soil. The grubs devour the grass and clover-roots in meadows, and, in cultivated fields, the roots of grain-plants, peas, and beans, rape, cabbage, etc., also turnips and potatoes; in gardens the roots of many vegetables and flowers, and, in particular, the underground parts of strawberry plants. If, on poor sandy soil, they can get nothing else, they devour the bark of oak and fir. Cockchafers take three to four years for their development: four in England, North Germany, and Central Germany; three in South France, Switzerland, the Rhine district, and Holland. In regions where the insect is abundant, every third or fourth year is a “chaferyear,” when the beetles appear in millions, while scarcely a cockchafer can be found in the intervening years. In districts less infested there is not the same marked distinction. It therefore appears that cockchafers and their larvæ are to be reckoned as injurious insects: their occurrence, however, is local. _Natural enemies_: moles, shrews, bats, foxes, crow-like birds, starlings, sparrows, owls, and the large species of ground-beetle. Winter floods do no harm to the grubs, which are then deep in the ground,—but this is not the case with floods occurring in summer, when they are near the surface eating the roots of the plants. _Remedies_: Collecting the grubs turned up during ploughing. Catching the cockchafers; this is very expensive, since it has to be done very energetically if most of them have left the pupastage. A part of the expense may, however, be recouped by using the cockchafers as manure.

The =Horse-chestnut Cockchafer= (_Melolontha hippocastani_) has a short slender caudal process, somewhat broader at the tip (Fig. 73). Its habits are in no way different from those of the preceding species.

The =Buckwheat Beetle= (_Phyllopertha horticola_), one-third to one-fifth of an inch long, without a caudal process. Shining blackish green, with yellowish brown elytra. Dark-coloured specimens are also found. The beetles appear in June; in some years they occur, like cockchafers, in large numbers. Habits of the beetle and of the small grub not markedly different from those of the cockchafer.

The =Rye Chafer= (_Anisoplia fruticola_), somewhat larger than the buckwheat beetle, in other respects very like it, but with a snout-like projection of the thickened skin of the head. Dark bronzy green, whitish on the under side. Wing-covers yellowish brown. On poor sandy soil, on the flowering ears of rye. The beetles gnaw the flowers.

[The =Garden Chafer= (_Anisoplia horticola_) is closely related to the preceding. The grub is very harmful to pastures.]

Family: =Elateridæ= (_Click Beetles_).

FIG. 74.—The Skipjack (_Agriotes lineatus_): 1, magnified larva, below
it the under side of the tip of the abdomen and the larva, natural
size; 2, the beetle; 3, under side of the head of the larva,
strongly magnified. _a_, maxilla; _b_, lower lip; _d_, labial palp;
_e_, _k_, inner and outer maxillary palps; _f_, antennæ.
]

The Click Beetles (Fig. 74) are longish, of equal breadth all along, tolerably blunt at the hind end. Neck-shield strongly developed. Antennæ “serrated,” _i.e._ made up of three-cornered joints. Feet five-jointed. Looking at the under side a spine may be seen on the hinder margin of the prothorax (Fig. 75, _b_), and on the mesothorax (_c_) a furrow which receives the spine when the body is extended, but the spine is drawn out of it if the prothorax and mesothorax are lifted up from anything they happen to rest on (Fig. 75). A skipjack that has fallen upon its back first draws its antennæ and legs close to its body, and then bends this in such a way that the head and prothorax make an angle with the rest of the thorax and the abdomen. In this way the junction of the prothorax and mesothorax is lifted up, and the spine drawn as far as possible out of the furrow. As soon as the beetle has taken up this attitude, it can spring back into its usual position by lifting the two ends of the body and pressing the spine forcibly back into the furrow, whereby it is jerked against the ground with such a shock that its elasticity makes it spring into the air, where it turns round and comes down again ventral side below. The larvæ (“wireworms,” Fig. 74, 1) are like meal-worms, elongated, always flattened on the ventral side, and sometimes on the dorsal side as well. The head is dark brown, the twelve remaining segments of the body yellow to yellowish brown; the first three segments of the body bear three pairs of very small legs; the last segment has a pair of caudal pro-legs.

FIG. 75.—A Skipjack lying on its back and about to spring up. _a_,
head; _b_, spine of the prothorax; _c_, mesothorax; _d_, metathorax;
_e_, abdomen.
]

FIG. 76.—Grain-plants sown deep and shallow; a wireworm is devouring
the underground part of the stem of the first.
]

Many species of click beetle are quite harmless, since they only devour decaying vegetable matter, either in humus or in the rotting substance of dying trees. There are also species, however, the larvæ of which feed on the living roots of plants. The wireworms of _Lacon murinus_, which are tolerably thick and have a flattened tip to the abdomen, devour the roots of fruit trees, rose-bushes, various vegetables (lettuce, cabbage, onions, turnips) and flowers; they are principally to be found in garden soils rich in humus. The relatively small hairless wireworms which do great damage, especially to grain-plants, but also to potatoes, carrots, turnips, rape, hops, and almost all the plants of our arable land, belong to _Agriotes lineatus_ or _A. obscurus_; the larger and more hairy wireworms destructive in cultivated land almost all belong to _Athous hæmorrhoidalis_ or a related species. The species named above also do much damage in meadows and grass land. Those fields are most infested which bore grass or clover the preceding year. Wireworms are usually more destructive in dry soil than in wet. They devour all underground parts, but specially prefer fleshy organs (potatoes, turnips), as well as the underground stem-parts of grain-plants, working themselves up from the soil into the inside of the lower part of the haulm, where they destroy the plant by gnawing its base. They also often destroy, in young grain-plants, the region of the stem which extends from the remains of the seed to the surface (Fig. 76, _left_). In both cases the plant is killed by the wireworms; the injuring of the roots is less fatal. It is obvious that in shallow sowing only a small piece of underground stem is exposed to the attacks of wireworms, in deep sowing a much larger piece; besides this, a plant which has been sown shallow develops earlier a strong mass of roots, and in its young state can therefore offer a greater resistance to the destructive influence. Since wireworms require four or five years for their development, the same field is infested by them the whole year. The greatest damage is done in spring and autumn. When wireworms have gnawed into the lower part of the haulm, the lower leaves first turn yellow, and the death of the whole plant soon follows. _Remedies_: Repeated ploughing of fields infested by wireworms, so that rooks, starlings, wagtails, gulls, etc., can devour them. Perhaps, too, many larvæ are frozen. Sowing the seed as shallow as possible on infested fields (Fig. 76). Waste potatoes may be used as a means of drawing them from the crop.

Family: =Curculionidæ= (_Weevils_).