Urban Pest Abundance and Public Enquiries in Zurich 1991–2022

SIMPLE SUMMARY: Zurich’s Urban Pest Advisory Service (UPAS) gives the public the opportunity to report household pests and join attempts to reduce potential health threats. More than fifty thousand records, dating back to the 1990s, provide information on the changing prevalence of pest problems in Zurich. Cockroaches declined most notably over this period, possibly through the availability of effective gel baits. From 2010, there was much interest in bed bugs and awareness campaigns made travellers aware of how to avoid bringing bed bugs home after summer holidays abroad. In recent years the Asian tiger mosquito has been found in Switzerland and has raised much public interest, though few were identified in Zurich. During COVID-19 people spent more time at home, which may have led to more observations of wasps. ABSTRACT: Zurich’s Urban Pest Advisory Service (UPAS) aims to survey, control and reduce hazards posed by pests. Records submitted to the UPAS may not exactly correlate with abundance but can reveal patterns of change. These reflect changes in species, public and media perceptions and the effects of climate and COVID-19, along with the effectiveness of new pest controls. Records for Blattodea and Plodia interpunctella declined in the period 1990–2022, while Cimex lectularius and Psocoptera increased. Summer has typically revealed the largest number of insects reported and Google searches show parallel seasonal variations. The Blattodea declined five-fold over time, likely due to better pest control methods (gel baits). Aedes albopictus, though rare, was the subject of media reports and awareness campaigns, which resulted in much public interest. Vespidae are abundant and have been reported in sufficient numbers to warrant an analysis of seasonal records, suggesting that July temperatures affect numbers. COVID-19 restrictions led to more frequent reports of rodents, pigeons, Zygentoma and Stegobium paniceum. The long-term reporting to the UPAS gives a useful indication of the changing concerns about pests in Zurich.