Insecticidal Control of Paedogenetic Cecid Larvae in Mushroom Beds

γ‐BHC, incorporated at 50 p.p.m. in mushroom compost during the last turn of composting delayed the reproduction of paedogenetic cecid larvae without reducing the yield of mushrooms. Other insecticides were less satisfactory as they either did not control the larvae, were not sufficiently persistent or decreased the yield. Large cecid populations did not depress yields on normal composts but a proportion of the larvae migrated on to the sporophores, thus reducing the value of the crop.