24 



The Wheat Bulb Fly. 



[APRIL, 



of water might be used, though this is apt adversely to affect 

 the germination of the seed. The solution may be poured 

 over the grain spread over the barn floor, or the seed may be 

 emptied into the vessel containing the solution and allowed 

 to " steep " for 10 or 15 minutes. A slightly weaker solution 

 of formalin, 1 pt. to 25-30 gal. of water, may be used as 

 a preventive against " Covered Smut " in barley and " Loose 

 Smut " in oats, but the duration of the soaking should not 

 exceed 10 minutes. If the seed cannot be sown within a few 

 hours after " steeping," it should be spread out on the barn 

 floor in a current of air and thoroughly dried. The general 

 adoption of these measures throughout the country will lead 

 to a marked improvement of corn crops both in quality and 

 quantity. 



One of the worst, and at the same time the least often 



recognised, of wheat pests is the Wheat Bulb Fly (Hylemyia 



coarctata). stated to be now prevalent in 

 The Wheat Bulb Fly* W- 1 x i 



j Dorset. This pest is almost always 



responsible for considerable " thinning " of winter wheat 

 during the spring, notably perhaps in East Anglia. Occasionally, 

 however, it appears in sufficient numbers to cause an epidemic, 

 when whole fields of wheat may be destroyed. Such an 

 epidemic occurred in Cheshire in 191 7. 



The damage is caused by the maggot (or larva) of the fly 

 which feeds within the growing shoot of the wheat. Each 

 attacked shoot is killed, with the result that if the wheat is 

 weakly or the maggots are very numerous, the whole plant 

 dies. It should be noted, however, that if the wheat does not 

 actually die, considerable recovery is possible owing to the 

 powers of the plant to put out fresh tillers. A field which now 

 or later looks very " seedy " may produce a very fair crop, 

 and it is therefore unwise to decide too soon on ploughing. 

 Naturally anything which can be done to stimulate rapid 

 growth will increase the chances of recovery. With regard 

 to re-sowing, barley is probably the best cereal to choose, 

 since it is not attacked by the fly, and sowing can be deferred 

 until it is clear that there is not sufficient wheat left to make a 

 crop. 



The habits of the fly are still not fully known, and hence 

 it is difficult to advise other treatment. The maggots now 

 feeding will turn to pupae (or chrysalides) in the soil, from which 

 the flies will emerge in June. These flies live some weeks, 



* See also note on p. 37. 



