182 THE BRITISH NATURALIST. [August 



crops being destroyed. In England the damage seems to vary from 

 one to twelve bushels per acre. There are two distinct modes of 

 attack, luckily one only, the less serious, takes place in our islands. 

 The presence of the attack that we suffer from in England may be 

 known by the stem elbowing down just above the second node, where 

 the maggots are usually to be found. The injury is caused by the 

 white grubs sucking away the juices of the stem, and so weakening it ; 

 the stem and ear above become stunted, and then finally bend down as 

 if weather-beaten. The second mode of attack is not recorded so far 

 in England, and I agree with Professor Riley in that it is not likely to 

 appear. This second method of destruction is in young Autumn-sown 

 wheat. The maggots arising from the ova produced by the autumn brood 

 lie in the base of the leaves just above the root, near the surface, and 

 when they assume the "flax-seed " stage they rest between the leaves and 

 stalk. The plant does not " tiller," the leaves become broader and 

 darker, and the central leaflet does not appear. This latter attack is 

 the one the Americans suffer so seriously from. It is absent in 

 England because our Autumn-sown wheat is put in much later than the 

 American. The second brood of flies are dead before our Autumn- 

 sown crop is up. It is strange no autumn brood came from the 

 numerous flax-seeds I gathered in South Devon last year ; but some 

 began to hatch during this spring. There is no doubt that the larvae I 

 found in the " couch " in South Devon in September were the second 

 brood, which do not seem generally to make their appearance in 

 the west. When the second brood does appear it is evidently earlier 

 than in the eastern counties. 



Now, as to the methods of preventing and destroying this pest. 

 First I should mention that the Hessian Fly has many natural enemies 

 in the being of small Ichneumon flies. These parasites deposit their 

 eggs in the larvae and even ova of the Hessian Fly, and eventually 

 destroy their vital powers. They luckily are very abundant in our own 

 country, often more of those Ichneumon parasites will be bred from the 

 flax-seeds than adult Hessian Flies. We must be very cautious, then, 

 in advising any methods of cure, for by destroying the " flax-seeds " we 

 also destroy numbers of these valuable parasites, which keep down an 

 excess of this insect pest. Three of these parasites have been busily at 

 work in South Devon, and must have caused great havoc amongst the 

 Hessian Fly. 



There are certain points that are recommended by various economic 

 entomologists in America and elsewhere that are of great importance, 

 if we are not satisfied with Nature's prevention, by parasites. First 

 and most important of these is the destruction of " flax seeds " in sift* 

 ings or light grain. The little brown puparia are shaken off the straws 

 in threshing, and fall with the " cavings " and light grain. Now, most 



