Note on the Wheat Bulb Fly (Leptohylemyia coarctata, Fall.)

Abstract

This insect has been known for many years as the cause of serious loss to the wheat crops in this country and on the Continent, having been first recognised in 1882, although it probably occurred before that year. In some seasons the damage occasioned by this fly is so severe as to cause the almost complete destruction of the crop in some fields, although more often it results in the crop being made thin and patchy. The damage first becomes apparent in March and April, when the leading shoot of the young plants attacked turns yellow and the plant if small or weak dies off. The injury is caused by the older larva, which feeds within the young shoot. This destruction of the young plants usually occurs in patches about the field, and the bare patches so caused increase in size owing to the larvae moving in the soil from plant to plant, each larva being thus able to destroy several plants. In addition to winter wheat this pest can attack winter barley and winter rye, although such attacks are rare in this country. It can also attack couch grass. Neither oats nor any other crop is attacked. In Great Britain the most severe damage due to this insect has generally occurred in the eastern countries of England and Scotland, although serious injury has also occurred in various other districts, and the severity of the attack has varied enormously from season to season. Damage due to this pest has also been reported from Middle and South Russia, Germany, Austria, Holland, Sweden, Norway, Denmark, France, Tunisia and Mesopotamia.