THE EFFECTIVENESS OF RESIDUAL INSECTICIDES AGAINST THE VARIED CARPET BEETLE ANTHRENUS VERBASCI (L.) AND THE IMPLICATIONS FOR CONTROL OF THIS PEST IN MUSEUMS

Abstract:
A number of species of carpet beetles (Anthrenus spp) that are household pests attack museum collections and can cause severe damage to natural history specimens, textiles and ethnographic objects. Many of the species such as the varied carpet beetle, Anthrenus verbasci. have their origin in birds' nests and may spread into collections from the nesting sites found on many museum buildings. Residual insecticides are commonly applied to control such infestations but these treatments have often met with limited success. Much of the laboratory testing of insecticides has been carried out against the adults, which appear to be relatively susceptible to organophosphorous, carbamate and pyrethroid insecticides. However, tests against the larval stages have usually been carried out by confining larvae on treated woollen textiles and recording the damage to the fabric and the mortality of the insects that fed upon the material. To reflect accurately the need to kill larvae as they wander over treated surfaces we have evaluated the effects of wood panels treated with six insecticide formulations on late instar larvae of the varied carpet beetle. The test formulations were applied as residual sprays or dusts at comparable active ingredient levels. For some formulations there was survival of a few larvae even after 35 days continuous exposure to the recommended label dose of insecticide. It is, therefore, likely that some insecticide treatments applied in museums to control carpet beetle infestations and prevent damage to collections will not be effective and alternative control measures should be sought.