With 5 Text-figures)For studying the population of pea-midge cocoons, larvae and pupae in the soil, a new method of examining the 'float' obtained from washing soil through the wet-extraction apparatus is described.Examination of soil samples in the summer of 1957 from fields which carried heavily attacked pea crops in 1956 indicated that pupae were present at depths of 0-3, 3-6, 6-9in., respectively, from 18 June onwards, and that the peak emergence of midges was in the period 28 June-a July; observations on adult activity in pea fields confirmed this. Small numbers of pupae were recovered throughout Similar studies on pea fields in 1957 showed the build-up of the cocoon population and the rate of pupation of this generation of larvae. The first flight of 1957 was composed of individuals from the 1956 generation and was far larger than the second flight, which was composed of some 1956 generation and part of the first 1957 generation.There were indications that increases of temperature might accelerate pupation with a resulting earlier emergence of adults.The size of midge populations recorded from soil from green pea and dryharvesting pea fields tended to be similar and appeared to be related to sowing date.

T o obtain reliable estimates of wheat bulb fly populations in time to provide advice on seed treatment of the following crop a method of collecting eggs in trays of soil placed in fields has been devised. The trays are examined by 20 August when half of the eggs have been laid.