HESSIAN FLY.

Wairarapa Daily Times, Volume XVI, Issue 4992, 3 April 1895, Page 3

HESSIAN FLY.

(Ctaiomyia dulructw.j

[BvT.W.Kirk.F.L.S.&c.Losdon,]

< are two main broods in tho ' year—namely, one in the autumn, when the flies emerge from the pupa cases, and deposit their eggs in the creases of the leaves. The tiny maggots sopn hatoh out, and work their way down to tho crown of tho root, as shown in the cut Fig. 1. The attacked plants soon become yellow and weak. The other brood appears in summer, the eggs being laid on the leaves as before. The eggs of, this second brood, vary greatly in number—from as few as fifty, to as many as 160. The eggs are bright-colored, varying from pale •to bright red—in some caseß almost scarlet. In four or five days, tiny yellowish maggots appear, and in their turn, work their way down between the shoath and the stem, till they reach one of the lower joints-usually the srst .or second—near which they MC<lo, and suck the ■ juices from the win. -..(See Fig, 9, which shows strawawith the sheath removed). I have counted as many as thirty-two .clustered near a single joint. • Iu about three weeks the maggots, having ombedded themselvos in tho straw and become full-grown, harden, turn brown, and assume tho so-called chrysalis or "flax seed" state, from which ' the tiny flies emerge in the autumn to attack the young wheat. Some flies, however, remain in the pupa state for over, twelve months—a provision of Nature to protect the species from extinction, but ono not appreciated by farmers. The plant, being deprived of a great portion, of its nourishment, succumbs according to tho severity of the attack; the grain is badly developed; the stem becomes too jjkk tQ support tho weight of the Hcii} and bends down to the ground, Damp, mild weather is always favourable to the development of the pest, and the attacks are more or less periodic, several years of comparative immunity being followed by one of exceptional loss, In theseexceptionalyears, especially, the artificial means of reducing the numbers of the invaders should be carefully used; but it should also be borne in mind that in this, as in the fight against any other pest, unanimous actionamongst neighbors is absolutely necessary in order to .obtain the greatest good; otherwise one man may be working hard at ' means of destruction while his neighbour, through carelessness, is . doing his very best to increase the : nuisance,

The Hessian fly attacks wheat, barley, and rye, but has never been found on oate. Emedies suggested.—ln infected districts abstain for a couple of seasons from growing crops subject jtojtttack, so as to starve the pest If WPNiannot be done, bow late, in order that the first brood may not find young wheat on which to lay its eggs. Self-sown wheat should also be cut, or it will form a harbour for the fly, Plough infested fields as soon as possible after harvest, using a skim coulter plough, so as to thoroughly bury the stubble, Caref ally burn all screenings or rubbish from the threshing-machine, as these form perfect nurseries for the pest. Another means adopted with some success is to sow strips of early wheat as bait. The first brood will attack these, and the whole strip is then ploughed in before the crop is above ground.

When the larva are discovered in early stages, dressings of fertilisers have been found of great assistance, by stimulating a strong, healthy growth, and so enabling the plant to withstand an attack to which it « otherwise succumb, ie are soveral species of natural enemies—chiefly Hymenoptera (four-winged flies), These will doubtless, in years to come, solve the difficulty, and restore the balance of nature ; but although nature will herself, in time, cure the evil, yet in years of special attack, at any rate, the farmei' cannot afford to fold his hands and wait for this, He should therefore use the mechanical means available for the suppression of the pest before it assumes such proportions as to bo beyond control.

It has been proved that the fly will, if grain is scarce, breed on certain grasses {Eolcus lanatus, Fhadum prutmse, Tritimm repm and others) so that care should be taken to clean up the rank growths on the margins and comers of fields. Considerable attention has been paid, especially in America, to the poAiction of varieties of wheat. *{P?i on account of the hardness of their strawfl, are more or less proof against the attacks of 0. destructor. An effort is to be made before next season tointroduce small quantities of these for experimental purposes, in order to ascertain whether they may suitably be substituted for the kinds usually grown here.