On the presence of Vespoidea on an Italian racecourse

Abstract: Hymenoptera Vespoidea can represent a risk for humans in populated areas as they frequently nest near houses, within walls, or on trees in public parks. Moreover, their abundance can result in adverse encounters with people. In the present work we investigated the presence of Vespoidea in a racecourse in the city of Milan (northern Italy). In the past, the presence of nests of Vespula germanica under the ground has caused harm to humans and horses. The survey was conducted from May to October 2016 using 28 TAP TRAP© baited with beer and checked every 15 days. Specimens of only three species, V. germanica, Vespa crabro and Polistes gallicus, were captured in the period. Many V. crabro were captured on each monitoring date; in comparison, the other two species were very low. No V. gemanica nest were found in the proximity of the traps. The presence of many burrows due to voles in the area that could facilitate the settlement of V. germanica, causing problems to horses and people, should be taken in account to limit the settlement of this species.