Page:Encyclopædia Britannica, Ninth Edition, v. 24.djvu/572

Rh 536 W H E W H E and 14 to 16 smaller joints, which diminish in length towards the ends. The male fly is smaller than the female ; the abdomen terminates in two claspers. The female lays in the spring 40 or more eggs upon the leaves of the corn plants, wheat, barley, and rye ; oats are not affected. The larvae are hatched in about 5 or 6 days, and make their way down to the axils of the leaves, feeding upon the sap which is passing up the stem. After a few weeks they are transformed into the &quot;flax seed&quot; pupae, which are usually found just above the second joint of the stem. From these pupae the autumn brood of flies emerge ; these lay eggs, and their larvae tide over the winter in the pupal condition. Sometimes only one brood is produced in the year. The injury done to _the plant by the larvaj living upon the sap usually causes the infected plants to bend over just above the second joint ; this renders them easily distinguishable from the healthy plants. The numbers _ of this most injurious insect are fortunately kept down to a considerable extent by parasites. Five species of Chalcididaz are known to be parasitic on 0. destructor in America and six in Russia. Fortu nately these are not absent in Great Britain. When a crop has been infected by this pest, the corn should be reaped above the second joint, and the stubble carefully ploughed in. A sharp look-out should be kept for the appearance of the &quot;flax seed&quot; both in the plant and in samples of corn, especially if the latter has been badly cleaned. Some species of wheat seem to have a greater power of resisting the attacks of this insect than others, but as yet very little definite information can be given on this point. These two pests do damage to the amount of millions of pounds every year in North America ; but none of those mentioned before them are either common or destructive on that continent. Cephus pygm&us belongs to that destructive group of the Hymeno- plcra, the saw-flies, and is commonly known as the corn saw-fly. The insect is black in colour, with a large head and prominent eyes. The mouth parts are yellow, and in the male the legs are the same colour. The female is darker and has its black ovipositor slightly exposed. Whilst the wheat is still young and tender, the female pierces the stalk below the forming ear and there deposits an egg. The larva, which hatches out in about ten days, is when full-grown about half an inch long, whitish in colour, with a brown head. It differs from the ordinary saw-fly larva in having but three pairs of legs. This larva bores its way down the stem, cutting through the knots, and about harvest time it cuts the stem nearly through at its base. The larva assumes the pupal stage in the lowest part of the stem and remains in this condition till the following spring, when the perfect insect emerges. Plants which have been affected by this insect can easily be recognized by their thin empty ears. Since the insect passes the winter in the stubble, every effort should be made to destroy this wherever the disease has been prevalent. The caterpillars of some species of Lepidoptcra do considerable damage to corn crops. On the Continent the larvae of Agrotis clavis (segetum) devour the roots of wheat and are especially destruc tive to autumn-sown crops. Tinea granella, a member of the family Tineidie, causes much harm to grain in store. This small moth, of a dusky white colour, lays one or two minute eggs upon each grain ; as soon as they are hatched, the caterpillars bore their way into the grain, and by means of a web bind several grains together. Through these it bores minute passages and lives in them, devouring the substance of the grain. The larvte ultimately withdraw to the angles and corners of the granary; hence, wherever this pest is prevalent, care must be taken to keep the building free from dust, cobwebs, &c. There is a member of the Coleoptera which is frequently mistaken for the above-mentioned pest. This beetle is known as Troyosita mauritanica ; it is supposed to have been introduced from Africa. The larva is f inch long, with a whitish body, bearing tufts of hairs and a brown head. It gnaws the corn grains and lives on their contents. The beetle is carnivorous, and is said to compensate for the damage its larva causes by devouring the above- mentioned Tinea granella. Another beetle, Calandra granaria, the corn weevil, also attacks stored grain. The eggs are deposited in the grains of corn and the larva spends its life therein, living upon the substance of the grain, and ultimately turning to a pupa. It leaves the grain first upon attaining the mature state. The larvae of Elater (Agriotes) lineatus and of other species of this genus are amongst the most destructive insects known to agriculturists. They are commonly known as wire-worms from the exceedingly tough character of their skins. The mature beetles are known as skip-jacks, from the power they possess of regaining their normal position when placed on their back by means of a loose articulation between the pro-thorax and the meso-thorax. This when put in action causes the beetle to jump into the air, and they usually fall on their feet. The wire-worms have a rather flattened body, yellowish brown in colour ; it consists of twelve segments, and bears three pairs of legs. The larvae live for several years, and then, burying themselves deep in the earth, emerge as the perfect insect in about a fortnight. The beetles pair in June, and the female deposits her eggs upon blades of grass or the sheath ing leaves of corn. The best preventative for this pest is clean farming and scarifying the land after harvest, so as to kill all roots which might serve as food for the wire-worms. When a crop is badly attacked, soot or gas lime may be applied and the land well rolled to compress the earth. The numbers of the larvae are to some extent kept down by moles and insectivorous birds. The cockchafer, Melolontlm vul gar is, is injurious to corn crops, in both its mature and its larval con dition. During the former state it devours the leaves of wheat and of most other grasses, trees, and shrubs. The larva, which is very voracious, lives upon roots. This larva is very thick and fleshy, of a whitish hue, with three pairs of legs ; it usually lies in a curled-up position. The larval condition lasts several years ; FIG. 6. Wire-worm (Elater lineatus), but ultimately the larvae become showing insect and larva, pupae, and in this condition live through the winter. Much may be done to prevent the spread of this pest by shaking the cock chafers from the trees, amongst the leaves of which they hang, and destroying them. They are eagerly eaten by pigs and poultry. An allied but much smaller species of beetle, Anisoplia horticola, with much the same habits as the above, also occurs in England, and attacks wheat and grass crops. Millepedes, although they are not insects, but one of the groups which compose the larger division Tracheata, must be included in an account of the pests which attack wheat. The English species which is most destructive to wheat, barley, and oats is Polydcsmus complanatus. Millepedes pass their life underground, and are sometimes mistaken for wire-worms, but can be at once distinguished by the great number of their legs. They affect damp places, which should be drained, and no rubbish or litter should be left lying about. Ear-cockle is due to the parasitism of a small white nematoid worm, known variously as Anguillula ( Vibrio) tritici or Tylenchus scandens or tritici. These worms cause the formation of a brownish black gall upon the wheat ear. When the ear ripens and falls to the ground, the nematodes escape from the gall and live in the damp earth. Ultimately they make their way on to a young plant, and, as the ear forms, they pass into it and pair inside the gall which has been caused by their presence. The female lays numerous eggs, from which young nematodes hatch out, until the gall is quite full of them. As long as the gall remains hard, the larvae are motion less ; but they become active in moisture, and develop into the adult state. If the surrounding conditions are unfavourable they will remain in the larval state for years. They are capable of resisting great extremes of heat and cold, and are apparently un affected by many poisons. Allied species affect the roots of wheat, grasses, and other plants. For fungoid diseases, see FUNGUS, vol. ix. p. 831, and MFLDEAV, vol. xvi. p. 293. (A. E. S.) WHEATEAR, as a bird s name perhaps of doubtful meaning, 1 though Taylor, the &quot;water poet&quot; (d. 1654), in whose writings it seems first to occur, and Willughby ex plain it (in the words of Ray, the latter s translator) as given &quot; because [in] the time of wheat harvest they wax very fat.&quot; It would seem also from this author to have been originally the local name for the species in Sussex, on the South Downs of which county its capture in a very simple kind of trap has been the occupation of many generations of shepherds, who thereby have made an excellent trade, since Wheatears in their proper season, from the end of July till towards the end of September, are justly esteemed for the table and fetch a price that for many years has been con tinually rising owing to the failing supply, which is chiefly due to the bringing under tillage of so much of the sheep- walk, heath, down, and other open country that was formerly in a natural condition. The Wheatear, the Saxicola cenanthe of ornithologists, is one of the earliest migrants of its kind to return to its home, often reaching 1 The vulgar supposition of its being an euphemism of an Anglo- Saxon name (cf. Bennett s ed. of White s Nat. Hist. Sellwrne, p. 69, note) must be rejected until evidence that such a name ever existed be adduced. It is true that &quot; Wliittaile &quot; (cf. Dutch Wit&taart and French Culblanc) is given by Cotgrave in 1611 ; but the older names, according to Turner, in 1544, of &quot; Clotburd &quot; ( Clod-bird) and Smatch ( = Chat) do not favour the usual derivation. &quot;Fallow-chat&quot; is another old name still locally in use, as is &quot;Coney-chuck.&quot;