Entomologia Experimentalis et Applicata 93: 97–104, 1999. © 1999 Kluwer Academic Publishers. Printed in the Netherlands. 97 Deathwatch beetle, Xestobium rufovillosum, in historical buildings: monitoring the pest and its predators S. R. Belmain 1,∗ , M. S. J. Simmonds 2,∗∗ & W. M. Blaney 1 1 Department of Biology, Birkbeck College, University of London, Malet Street, London WC1E 7HX, UK; 2 Jodrell Laboratory, Royal Botanic Gardens, Kew, Richmond, Surrey TW9 3AB, UK; ∗ Current address: Natural Re- sources Institute, University of Greenwich, Central Avenue, Chatham Maritime, Kent ME4 4TB, UK; ∗∗ Author for correspondence (Fax: 44 181 332 5340; E-mail: M.Simmonds@rbgkew.org.uk) Accepted: August 17, 1999 Key words: deathwatch beetle, Xestobium rufovillosum, Coleoptera, Anobiidae, timber pest Abstract Trapping and monitoring experiments were conducted in the roof spaces of four buildings infested with deathwatch beetle, Xestobium rufovillosum de Geer (Coleoptera: Anobiidae). Data from sticky traps and an ultra-violet insec- tocutor showed that adult deathwatch beetles were trapped from May to July. The beetles were attracted to natural and UV light, and more beetles were caught on white coloured traps than yellow, blue or red traps. Deathwatch beetles comprised 30–40% of all arthropods caught. The weekly trap catch of all arthropods, including deathwatch beetle, was positively correlated with ambient temperature. Adult beetles flew in buildings at ambient temperatures greater than 17 ◦ C. Arthropods caught in the buildings were categorised as resident, over-wintering or non-resident arthropods. Predatory spiders comprised 13% of arthropods caught and the predatory beetle, Korynetes caeruleus de Geer, was found in all four buildings. There was no evidence of other predators or parasitoids of the deathwatch beetle Introduction Despite the damage caused to timber in buildings of historical importance by the deathwatch beetle, Xesto- bium rufovillosum de Geer (Coleoptera: Anobiidae) (Fisher, 1938), the behaviour of deathwatch beetles in buildings is poorly understood. For example, the literature suggests that adult beetles do not fly in build- ings because the beetle has never been reported to fly (Maxwell-Lefroy, 1924; Kimmins, 1933; Fisher, 1938; Hickin, 1963; Harris, 1964). We could find no reference to the dispersal of deathwatch beetles in forests, although the ‘beetle can walk long distances when inclined to do so’ (Fisher, 1938; Hickin, 1963). Previous literature has argued that infestation of build- ings occurred when infested timber was brought into a building during construction or repair, the beetles then dispersing in the building by walking away from the original infestation (Maxwell-Lefroy, 1924; Fisher, 1938). However, no experiments have tested whether deathwatch beetles fly in buildings. Sticky traps are extensively used to trap pest in- sects, often using an attractive colour, for example, blue for thrips (Coli et al., 1992; Vernon & Gillespie, 1995), or a chemical such as Blattellastonoside for cockroaches (Sakuma & Fukami, 1993) to increase efficacy and thereby reduce pest density. Although un- baited sticky traps are sometimes used in buildings to monitor timber pests they have not been used to monitor deathwach beetles. In this study, traps de- signed to catch walking and flying insects were used to sample deathwatch beetles and other arthropods in in- fested buildings. Knowledge about arthropod diversity could help establish potential infestation risks associ- ated with a building’s degree of exposure to the outside environment, as well as indicate the presence of po- tential biocontrol organisms of the deathwatch beetle, for example, spiders and the clerid beetle, Korynetes caeruleus de Geer (Hickin, 1963).