Twistedwinged Parasites Order Strepsiptera

Identification: Minute insects, 0.5-4.0 mm., the sexes quite different. cf: blackish; FW reduced to short clublike structures, HW large and fanlike, with a few weak radiating veins; eyes bulging; antennae 4- to 7-segmented, some segments with a long lateral process; tarsi 2- to 5-segmented; mouth parts chewing but usually reduced. 9: wingless; usually lacking legs and antennae; mouth parts generally vestigial. Metamorphosis complete, with hyper-metamorphosis (see p. 41).

Similar orders: Male strepsipterans are somewhat beetlelike, but can be recognized by the characteristic wings and antennae. Females are generally saclike and without appendages, and must usually be recognized by their location in a host insect. Immature stages and habits: Strepsipterans are internal parasites of other insects. Adult males on emergence leave the host and fly about; females of most species never leave the host. Each female produces many (a few thousand) tiny larvae, which have well-developed legs and are very active; they leave the host and enter another host, where they molt to a legless stage. Most strepsipterans have bees or various hoppers (Homoptera) as hosts; a few attack insects in other orders. The host is injured but rarely killed; the sex organs may be damaged or the shape or color of the abdomen may be changed. Parasitized hosts often can be recognized by the body of the parasite protruding from between the abdominal segments. If such hosts are caged, male strepsipterans frequently can be reared from them. Adult males are very seldom encountered.

Importance: These insects are of no economic importance. Classification: Four families, which are separated by the tarsal and antennal characters of males. No. of species: World, 300; N. America, 60.

MENGEIDS Family Mengeidae Not illus.

Identification: Tarsi 5-segmented, with 2 claws. Antennae

STYLOPIDS, HALICTOPHAGIDS, & ELENCHIDS 207

7-segmented, 3rd and 4th segments with long lateral processes.

Only 1 member of this family, Triozocera mexicana Pierce, is known from the U.S.; the female of this species is unknown, but the male has been taken in Texas. Females of some European mengeids are free-living as adults, and are usually found under stones; these mengeids are parasites of bristletails (Thysanura, see p. 60).

STYLOPIDS Family Stylopidae Identification: Tarsi 4-segmented, without claws. Antennae 4-to 6-segmented, only 3rd segment with a lateral process

This family is the largest in the order, with about 40 species in N. America. Most stylopids are parasites of bees (chiefly Andrenidae and Halictidae); a few parasitize vespid or sphecid wasps.

HALICTOPHAGIDS Family Balictophagidae

Identification: Tarsi 3-segmented, without claws. Antennae 7-segmented, 3rd to 5th segments with long lateral processes, last segment elongate.

This family is small (14 N. American species) but widely distributed. Most species are parasites of leafhoppers, tree-hoppers, and spittlebugs; 1 species attacks planthoppers and pygmy mole crickets.

ELENCHIDS Family Elenchidae Not illus.

Identification: Tarsi 2-segmented, without claws. Antennae 4-segmented, 3rd segment with a long lateral process.

The members of this small family are parasites of planthoppers (Fulgoroidea).

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