MANKIND AND THE INSECT 321 



saw-fly lias been guilty of very great injury to crops on 

 the Continent, but so far its depredations in Britain have 

 been relatively slight. 



The fourth and fifth ears in the photograph illustrate 

 respectively the conditions which follow attack by the 

 Hessian fly (Cecidomyia destructor) and the wheat midge 

 (C. trititi). Both these insects belong to the gall-midge 

 family (Cecidomyidoe) ; but, as it happens, neither of them 

 gives rise to a gall. The first is supposed to have been 

 introduced into America in fodder brought over by the 

 Hessian troops during the war of the revolution — whence 

 its popular name. The eggs are laid on the leaves of the 

 cereal (usually wheat, barley, or rye) in May and June. 

 The minute larvae work their way beneath the leaf-sheath 

 and stem of the plant — a favourite point being just above 

 the first or second knot. Here they feed upon the sap, 

 either singly or several in company, and eventually pass 

 into the pupa state — the puparium being brown in 

 colour and almost exactly like a flax seed in shape and 

 size. The damage to the plant is very serious. The ear 

 becomes stunted, and the stem — weakened by loss of sap 

 — bends over just where the larvae are located. The 

 Hessian fly has been responsible for incalculable loss both 

 in Europe and America, but it has not caused serious 

 damage in Britain since 1887. Indeed, there are those 

 who believe it to be practically extinct in this country ; 

 but this is a mistake, as farmers may one day find to their 

 cost. 



Like the Hessian fly, the wheat midge is also known 

 in both hemispheres. The female lays her eggs in the 

 florets of the cereal, and the minute larvae (" red mag- 

 gots ") feed upon the developing grains. Sometimes the 

 ears are so badly infested that a loss equal to one-half of 



the crop results. 



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