The Strepsiptera (known in older literature as twisted-winged parasites) are an order of insects with ten families making up about 600 species. The early stage larvae and the short-lived adult males are free-living but most of their life is spent as endoparasites in other insects such as bees, wasps, leafhoppers, silverfish, and cockroaches.
Appearance and biology
Male Strepsiptera have wings, legs, eyes, and antennae, and look like flies, though they generally have no useful mouthparts. Many of their mouth parts are modified into sensory structures. Adult males are very short-lived (usually less than five hours) and do not feed. Females, in all families except the Mengenillidae, are not known to leave their hosts and are neotenic in form, lacking wings and legs. Virgin females release a pheromone which the males search for. In the Stylopidia the female has its anterior region extruding out of the host body and the male mates by rupturing the female's brood canal opening which lies between the head and prothorax. Sperm passes through the opening in a process termed hypodermic insemination. Each female produces many thousands of triungulin larvae that emerge from the brood opening on the head, which protrudes outside the host body. These larvae have legs (which lack a trochanter, the leg segment that forms the articulation between the basal coxa and the femur) and actively search out new hosts. Their hosts include members belonging to the orders Zygentoma, Orthoptera, Blattodea, Mantodea, Heteroptera, Hymenoptera, and Diptera. In the Strepsipteran family Myrmecolacidae, the males parasitize ants while the females parasitize Orthoptera.
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