'90 AGRICULTURAL RESEARCH AND THE FARMER : 



example of a combined insecticide, a subject which has received 

 considerable attention during the last four years. It is a subject 

 of the utmost importance to the fruit-grower, who for economic 

 reasons must limit the number of his applications. The same 

 end would be attained if insect eggs could be killed or prevented 

 from hatching, but hitherto this has not appeared very likely. 

 Recently American work has shown that Hme sulphur applied 

 at a certain time has marked egg killing powers, and similar 

 trials are in progress at Long Ashton. The work of testing 

 such washes is, however, necessarily slow, and though the position 

 looks promising, no clearly marked results have yet been obtained. 



School of Agriculture, Cambridge. 



Wheat Bulb Fly. — From time to time numerous complaints 

 have been made of serious damage to wheat by this pest in 

 various parts of the country, particularly in the eastern counties 

 of England and parts of Scotland. The worst attacks follow a 

 bare fallow or bastard fallow, and bad attacks also occur after 

 crops of potatoes, rape, swedes, turnips and mangels, especially 

 where the soil is bare during the summer, as would obtain with 

 poor crops of roots or where potatoes are lifted early or the tops 

 die off early in the season. One of the largest farmers in the Fen 

 counties reported that in 1920, owing to the pest, hundreds of 

 acres of wheat had been destroyed in that area, and the land 

 re-ploughed and sown with barley, and hundreds of acres bore 

 only half crops. The life history of the fly was not known, so 

 preventive methods had not been discovered. The question 

 has been investigated at Cambridge, and the life history appears 

 to be as follows : — The flies hatch out in June or July, and lay 

 their eggs in bare soil, about one-eighth of an inch below the 

 surface, in July, August and September. Most of these eggs 

 hatch out early in the following spring, as they are usually 

 found in the wheat plants in March and April. The larva on 

 hatching from the egg makes its way to the middle of a wheat 

 shoot, where it feeds at the base of the shoot, which it kills. 

 Several plants may be attacked in succession. When fully fed 

 the larvse make their way into the soil, where they pupate about 

 i\ to 2 inches below the surface. Pupation usually takes place 

 in May. 



The discovery of the life history of the fiy makes it possible 

 to conduct experiments into methods of prevention. The prob- 

 lem suggested is, how can the flies be prevented from laying their 

 eggs in soil where wheat is to be sown. In this connection the 



