DIPTERA OR TRUE FLIES. 201 



midges hatch out, and continue tlieir noxious habits. It is 

 strange, when collecting these flies in the field, how few males 

 one ever sees. But, on the other hand, where heaps of ma- 

 chine rubhish are left about, there in June, often hovering in 

 clouds above the heaps, males and females may be seen in 

 copula in equal numbers. This pest is not confined to Great 

 Britain, but is equally abundant in America. From personal 

 observation I find the female laj^s her eggs at dusk, about ten 

 to twenty in eacli ear. 



Prevention. — These flies are very delicate creatures, and cannot 

 escape through the soil unless close to the surface, where we find 

 the red puparia normally. Therefore, deeply ploughing in the 

 stubble in the following way cannot fail to do good — namely, 

 by having a skim-coulter attached to the plough in such a way 

 that it will take off an inch or so of the surface and tiirn it into 

 the preceding furrow, thus burying larvse and puparia to such a 

 depth that they cannot escape when matured. Another im- 

 portant thing to do is to destroy all infested rubbish from the 

 machines, for over those rubbish heaps, as already said, breeding 

 largely takes place. In America the plan of not reai)ing too 

 close and burning the stubble must also do good. 1). tritici 

 also feeds on timothy grass and meadow cock's-foot. 



The Pear Miuge (Diplosis pyrivora). 



During recent years attention has been repeatedly drawn 

 to the loss amongst pears caused by certain Cecid larvse. 

 The fly which gives rise to these was described as Cecidomyia 

 nigra by J\'reigen, but has been redescribed and named by 

 Professor liiley Diplonix pyrivm-a. It is destructive in America 

 as well as in Britain. Diseased pears become distorted about 

 the time they are slightly larger than the size of a cob-nut, 

 presenting a well - marked appearance by which they can 

 be always detected. The fly is a minute midge about the 



