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Accuracy of extracting wheat midge, Sitodiplosis mosellana (Gehin), cocoons and larvae from soil samples averaged 99 and 94% for a sieving method and a brine flotation method, respectively. The time required to process bulk soil samples containing wheat midge cocoons was almost twice as long by sieving as by flotation. The time required to process field-collected soil samples containing wheat midge cocoons was also significantly longer by sieving and longer for a silty clay loam than for a very fine sandy loam. Extraction costs varied from $1.65 to $3.99 per sample unit depending upon method and soil type. Sieve extraction is the best method for studies on population dynamics and flotation extraction is the best method for distributional surveys and density estimates.

Experimental plantings of three cruciferous root crops, radish, turnip and rutabaga, indicated that heptachlor applied in various ways gave the most consistently good control of root maggots ( Hylemya spp.). A comparison of different methods of application for maggot control in radish and turnip showed that the best materials gave the highest degree of maggot control as seed or furrow treatments to radish, and as furrow treatments to turnip. The efficiency of a number of insecticides for control was compared by furrow treatment to turnip. Heptachlor or aldrin at 1 pound actual toxicant per acre gave more effective control than any of the other materials used. Similarly, as broadcast treatments to rutabagas made before planting and mixed with the top 3 inches of the soil, heptachlor and aldrin at 2 pounds actual toxicant per acre were the most effective control agents.

Sitodiplosis mosellana (Gehin) was reared through one complete generation in the laboratory. For the adult stage, avoidance of handling, maintenance of at least 60% RH, low night temperature, and the provision of wheat plants at the correct flowering stage were important to survival. For larvae, adequate moisture was essential to induce them to leave their ecdysial sheaths, to penetrate the soil before diapause, and to promote diapause development. Adult emergence ranged from 10.6 to 51.6%, and at least 112 d at 2°C was required for optimal emergence.

Using oviposition as a measure of the preference of the cabbage maggot, Hylemya brassicae (Bouche), for various hosts in the family Cruciferae, the following species were compared: turnip, rutabaga, radish, cauliflower and black mustard. Significantly higher numbers of eggs were taken throughout the season from rutabaga and turnip than from radish and mustard and the fewest eggs were taken from cauliflower plants. Radish appeared to he particularly susceptible to oviposition for a very short period. Mustard growing as a weed would appear to be a significant source of second-generation maggots attacking cruciferous root crops later in the season.