S. Mahunka szerk.: Folia Entomologica Hungarica 61. (Budapest, 2000)

Diptera reared from nests of Vespa crabro in Hungary L. Papp Diptera reared from nests of Vespa crabro in Hungary — 8225 dipterous specimens of 19 species were reared from two Vespa crabro nests collected in the Börzsöny Mts (central N Hungary). Several species were found for the first time in this type of microhabitat. Key words: Diptera, larval medium, nests of Hymenoptera, Vespa crabro, Hungary. In the course of the project "Dipterous guilds of the small sized feeding sources in Hungarian low mountains" we were to collect a greater number of data on the species composition and frequencies of the guilds on small-sized sources by regular samplings and by simple but safe methods. One of our aims was to make an estimation: what is the contribution of those guilds feeding on small-sized sources to the species richness of the forest ecosystems? Some of the sampling sites were selected in low mountain forests also in the Börzsöny Mts (central North Hungary: Szendehely: Keskenybükki-patak valley and forests around it, Szokolya: Kő-hegy, above the Les-völgyi-patak valley and other sites). Among others, two Vespa crabro nests were found in this area, one of them early in 1997 and another one in 1999 (nests detected in late summer of the previous year), whose debris was transferred into laboratory vessels and adult flies were reared out in the laboratory at 20±1°. Their data and short description are as follow. Nest No. 1: Szendehely: Nagy-rét, February 9, 1997. Wild plum tree on the edge of a forest clearing, an old hollow cracked at its upper part (originally made by Dendrocopos major) at a height of 1.80 to 2.20 m. The outer diameter of tree at the hollow was 26 cm, diameter of the hollow was 15 cm; it was cut out in its entire height and the hornet's nest with the debris beneath to a depth of 20-21 cm (ca. 4 litres) were taken and transferred into a laboratory vessel (101). Altogether 1295 dipterous flies of 16 species were reared. Nest No. 2: Szokolya, Kő-hegy, January 31, 1999. An X-shaped oak tree, i.e. with two trunks and two main roots, slightly domed between the two trunks, this dome and all the four parts are hollowed both underground and above ground; the entrance hole was on ground amidst of that X (slightly larger than a mouse-hole otherwise). The volume of the hollow was ca. 20 litres, which was half filled with wood debris, particles of hornet's nests and acorns collected by mice. Wasps nested there in two consecutive years, and, later in the autumn Apodemus mice must have lived there. About the half of that content,