The distribution of Melittobia acasta (superfamily Chalcidoidea, subfamily Tetrastichinae) is widespread. It is found parasitising a number of genera of bees and wasps and various parasitic flies from Europe to Japan, North America, South America and New Zealand. This chalcid wasp can be very destructive in the rearing of bumble bees and solitary bees under artificial conditions. Once M. acasta is observed it is often impossible to save colonies because of its high reproductive capacity (400 to 600 descendants per host or cell), rapid life cycle and predominance of females