Subfamily Eupelminae

100 spp. in 10 genera in our area, TBA spp. in 35 genera worldwide(1)

All members of the subfamily are extremely sexually dimorphic. Males look like "primitive" chalcidoids, whereas females are highly modified for jumping and more closely resemble females of Encyrtidae. --Gary Gibson

Primarily idiobiont ectoparasitoids or predators of the immature stages of other insects and spiders concealed/protected in plant tissue or fibrous material. Larvae or prepupae of wood-boring beetles are hypothesized as the original hosts even though the majority of eupelmines apparently are ectoparasitoids of the larvae/prepupae of Diptera, Hymenoptera, and Lepidoptera, or are predators or endoparasitoids of the eggs of Araneae, Blattaria, Heteroptera, Lepidoptera, Mantodea, Orthoptera, and Phasmida.(2)

Because of modifications to increase jumping ability the flight apparatus and consequently the ability of female eupelmines to fly has apparently been reduced. Anyone who has observed female eupelmines in the field will note they jump so fast that you can't really see it. One common name that was suggested for the group was "back-rolling wonders" because the jumps are so powerful they tend to tumble on landing. Females prefer not to fly and will simply walk around until disturbed. Males however fly as readily as any other chalcidoid. It is possible that females were modified for jumping to enhance ability to escape very rapidly from predators (ants, spiders, etc.). Primitive eupelmids appear to have been parasitoids of wood-boring insects and thus females were exposed to predators while searching for concealed hosts on dead plants. This is not so for males and they retained the "groundplan" structure and their ability for flight, which enables them to still fly around in their search for mates. It has also been suggested that the fore wing color pattern of female Anastatus ("smoky" with either a white cross-band or anterior and posterior white spots) gives them an ant-like appearance when the wings are folded flat over the body and therefore through mimicry further protection against predators. The jumping mechanism of females is really neat because unlike other insects they do not use muscles inserted directly onto the legs to power jumping, Rather, very large dorsolongitudinal muscles in the thorax are used. When these muscles contract the thorax "contorts", which changes a longitudinal force of action into a vertical force of action to power the middle legs for jumping. A result of this is that females often die in a U-like position. --Gary Gibson

Gibson, G. A. P. 1995. Parasitic Wasps of the Subfamily Eupelminae: Classification and Revision of World Genera (Hymenoptera: Chalcidoidea: Eupelmidae). International Memoirs on Entomology 5: i-v, 1-421. (ResearchGate)