AbstractInvestigations in Scotland on Byturus tomentosus (Deg.) infesting raspberry show that the adults emerged from the soil in mid-May and fed on the young leaves and unopened flower buds. Egg-laying began about a week after the first flower opened, usually in early June, and most of the eggs hatched between the early green-fruit and the first pink-fruit stages. The larvae browsed on the surface of the fruit before burrowing into the receptacle. Pre-blossom applications of fenitrothion sprays killed many adult beetles and largely prevented larval infestation of the fruit, but sprays applied between 80% petal-fall and the first pink-fruit stage were more effective. Sprays applied up to first pink-fruit stage did not taint the first harvested berries and fenitrothion residues were negligible.