Notes on methods and analysis of ground nests of apoid wasps (Hymenoptera, Apoidea)

A large portion of species of apoid wasps (Spheciformes) place their nests underground. While nesting biology and structure of nests of cavity-nesting species are often studied, searching for nests in the ground is usually interpreted as very difficult or impossible. We present a simple and practical method employing plant stems to explore the profile (direction of inclination) and to measure their excavation depth and extent. This method is compared with other previously known methods for studying nests placed in ground. The paper also includes comments on the nest search technique.