AbstractIn eastern Scotland, overwintered adults of Byturus tomentosus (Deg.) begin to emerge from the soil about mid-May, which is well before the open-flower stage of the most commonly grown raspberry cultivars. The beetles feed on the flower buds and in some years are sufficiently numerous to cause extensive damage. Egg-laying begins as soon as the flowers open, and the earliest harvested fruits are usually those most heavily infested by the larvae. In experiments in which insecticides were applied at the 'pink fruit' stage, fenitrothion gave slightly better control than malathion, azinphos-methyl or tetrachorvinphos (Gardona), which in turn were better than propoxur or derris. In Scotland, where beetle populations fluctuate from year to year but are only occasionally large, a pre-flowering spray is considered to provide sufficient control to reduce any subsequent larval infestation of the fruits to negligible proportions, particularly since more than 90% of the larvae are likely to remain in the plugs when the fruit is picked.