The Suitability of Artificial Nests as Nesting Sites for Cavity-Nesting Wasps and Bees (Hymenoptera, Aculeata)

Populations of several cavity-nesting aculeate wasps and bees have been in decline due to a shortage of nesting sites and changes in agricultural landscapes. We tested the suitability of various natural and non-natural materials as nesting sites for aculeate wasps and bees in Finland. According to our results, natural materials such as reed and cow parsley stems and birch wood with holes, were more suitable for artificial nests than plastic straws. We developed a new type of nest containing natural stems and a wooden cube with drilled holes of various diameters. To compensate for the shortage of nesting sites, artificial nests made of natural materials can be used to provide breeding environments for several species of cavity-nesting aculeate wasps and bees native to the boreal zone. When artificial nests are used for research purposes (‘trap nests’), insects should be allowed to hibernate in the artificial nests under natural conditions instead of being frozen.