Trends in insect catch at historic properties

Warmer climate has the potential to increase the number of insect pests in historic properties. This possibility has been explored using the catch from some thirty thousand insect traps laid out in English Heritage properties over more than a decade. The trapping programme resulted from an increasing focus on integrated pest management (IPM). Trapping has been more frequent in London and the Southeast. Quarterly inspection and replacement has led to a detailed record of catch. Although these data were collected for management purposes, they offer the potential to assess the impact of environmental change. Variation in the number of traps placed out requires data to be expressed as catch rate (insects caught per trap). The record suggests an increase in the average catch of booklice (Liposcelis bostrychophila) summed across all the properties examined over the period 2000–2012. There was a striking increase in the prevalence of the webbing clothes moth (Tinea pellionella) even when accounting for the increasing use of attractant pheromones in traps. In addition, infestations (i.e. > 10 insects per trap) also seemed to increase. However, these increases over time are not likely to be attributable to increasing temperatures. Nevertheless, the catch rate for woolly bear larvae (Anthrenus spp.) at the London properties showed a weak correlation with temperature in the warmer seasons. If temperature were to increase across the 21st century, a dramatic increase in catch rate would be expected. However, it is hardly likely as the abundance of insects is not driven by temperature alone. Other factors such as: food, habitat, access points, housekeeping and indoor climate can all have an impact on insect numbers and on infestations within a property.