OBSERVATIONS ON THE OVIPOSITION BEHAVIOUR OF METASYRPHUS CONFRA TER (DIPTERA, SYRPHIDAE) AND THE DEFENSIVE BEHAVIOUR OF SOLDIERS OF PS’EUDOREGMA BAMBUCICOLA (HOMOPTERA, PEMPHIGIDAE)

Abstract

Observations on the oviposition behaviour of an aphidophagous syrphid fly Metasyrphus confrater and the defensive behaviour of soldiers of its prey aphid Pseudoregma bambucicola are reported. This syrphid lays its eggs in colonies of the aphid in winter when aphid soldiers are not a few in number, but weak in activity. In the autumn, on the other hand, when aphid soldiers numerous and active, oviposition occurs on nearby spider threads and not directly on the aphid colony. Thus, Metasyrphus confrater probably evolved an ovipositing strategy which is adapted to the activity of aphid soldiers. Soldiers of Pseudoregma bambucicola destroy the eggs and attack the first instar larvae of the syrphid when these two antagonistic organisms come into contact.