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Species guide - species detail

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Melittobia megachilis (tiny parasitic wasps)



Melittobia megachilis is a tiny parasitic wasp in the family Eulophidae. M. megachilis is a type of wasp that parasitizes different Megachile species and has been studied in M. brevis and M. centuncularis nests. When M. megachilis uses Megachilids as hosts, it can reproduce rapidly and potentially harm bee populations. This is an issue because Megachilids are commonly commercially used to pollinate alfalfa, cucurbit, avocado, eggplant, legumes, and other crops. This wasp can lay hundreds of offspring in a single cell of a Megachilid which then spreads to infest other cells, leading to the production of thousands more parasitoids.


Melittobia megachilis is an extremely small parasitic wasp with an average length of only 1.1mm-1.5mm. When looking at the facial features of M. megachilis, the species has medium-sized facial grooves that run separately to the facial scrobes and do not converge mid-face. The scape and the pedicel of the antennae in M. megachilis are amber to light yellow in contrast to darker flagellomeres. The costal margin of the forewing diverges at an angle and is often very visible and dark. These specimens can be hard to identify to species as they tend to deflate and shrivel when air-dried and have microscopic differences/characteristics.

Nest Structure

Melittobia megachilis infiltrates the nests of Hymenoptera. In this case, they solely infest the nests of Hymenoptera, most commonly different Megachile species. The wasps lay their eggs on the prepupae and pupae of bee species. When the eggs hatch, the wasp larvae consume the prepupae or pupae. Since M. megachilis is a very fertile species that can lay hundreds of eggs in multiple generations, bee cells can easily become overwhelmed with these parasites.

Hole Sizes

No information at this time.


In Minnesota, Melittobia megachilis is particularly prolific and can produce many generations with its multivoltine cycle.

Activity Period

Melittobia megachilis is active in Minnesota from mid-May to September.


Grissell, E. E. 2007. Torymidae (Hymenoptera: Chalcidoidea) associated with bees (Apoidea), with a list of Chalcidoid bee parasitoids. Proceedings of the Entomological Society of America 109(4): 123-136. Dahms, E.C. 1984. Revision of the genus Melittobia (Chalcidoidea: Eulophidae) with the description of seven new species. Journal of Entomology 10(2): 123-136.

Minnesota Record Map

These data are from the Minnesota Bee Atlas project.

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