Abstract Sticky-traps were used to monitor the seasonal activity of Anthrenus sarnicus Mroczkowski and other beetle pests within and in the vicinity of the British Museum (Natural History), London. A. sarnicus was the most abundant pest in the Entomology Building, General Herbarium and Museum grounds. Indoors it was caught on traps from April to October and outdoors from June to September. A. sarnicus was observed feeding on pollen of a number of plant species in the Museum grounds and 10% of those caught in the Entomology Building in 1983 contained pollen in their alimentary tracts, indicating that adults were entering the building from outdoors. Of the females, 40–50% from all trap locations had mated. Larvae were recorded in a sparrow's nest in a London building. The field habits of A. sarnicus were considered to be very similar to those of the native species A. verbasci (L.). Sixteen other species of stored product beetle were recorded, seven of which are not considered to be native to Britain.