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  • University of Guelph
  • Lucid via Discover Life

Commonly called twistedwing parasistes, these insects are mostly internal parasites of other insects. Males differ greatly from females in structure. Males have wide heads with compound eyes on the sides. Males also have fan shaped antennae. Their forewings have evolved into clublike structures and the hind wings are membranous and with out venation. Females are without legs, wings, antennae and often eye and remain in the host their entire lives. The females remain in the host with only their heads protruding. Males leave the host and find females to mate with. The newly hatched, well-developed larvae leave the female and fall from the host to the ground or to plants.

Twistedwing parasites enter their insect hosts as larva through joints or sutures when the host itself is still in its larval stage. From there they undergo what is called "hypermetamorphosis": They molt into another, less mobile, larval form and feed in the host's body cavity. From there they undergo holometabolous metamorphosis. Hosts are not usually killed by infection but may be injured. The shape and color of the abdomen may be changed and the sex organs of the host may be damaged. The male usually causes more damage to the host than the female. Common hosts are various species from the orders Orthoptera, Hemiptera, Hymenoptera and Thysanura.

  • Immatures:
    1. First instar (triungulin) has legs, high mobility
    2. Successive instars are legless and grub-like with reduced mouthparts
  • Adults:
    1. Females remain larviform, legless and wingless, partially projecting from host's abdomen.
    2. Males emerge with adult-like body; Large fan-shaped hind wings; small club-like front wings; Reduced mandibulate mouthparts; Antennae 4- to 7-segmented; often with lateral branching"-- (N.C. State University Entomology Dept.)

Taxonomic Category Scientific Name Common Name
Phylum Arthropoda Arthropods
Class Insecta Insects
Order Strepsiptera Twisted-winged parasites


[Species: Xenos ssp.]
Photo copyright Birgit Ehmer
[Species: Xenos. ssp.]
Photo copyright Birgit Ehmer
[Species: Elenchus tenuicornis ]
Photo copyright Hans Pohl

[Species: Mengea tertiaria ]
Photo copyright Hans Pohl
[Species: Xenos vesparum ]
Photo copyright Hans Pohl
[Family: Stylopidae ]
Photo copyright Dept. of Entomology: Penn State
[Order: Strepsiptera ]
Photo copyright E. R. Day
[Order: Strepsiptera ]
Photo copyright Hans Pohl
[Order: Strepsiptera ]
Photo copyright Rick Redak
[Species: Mengenilla chobauti]
Photo copyright Hans Pohl
[Species: Eoxenos laboulbenei]
Photo copyright Hans Pohl
[Species: Stichotrema dallatorreanum]
Photo copyright Hans Pohl
[Species:Stichotrema dallatorreanum]
Photo copyright Hans Pohl

Geographic distribution
North America
Number of Families 4 8
Number of Species 109 532

Natural history
Most Strepsiptera (also known as twisted-wing parasites) live as internal parasites of bees, wasps, grasshoppers, leafhoppers, and other members of the order Hemiptera. Only a few species that parasitize bristletails (Archeognatha) are known to be free-living in the adult stage.

Strepsiptera share so many characteristics with beetles that some entomologists classify them as a superfamily of Coleoptera. In fact, Strepsiptera and certain parasitic beetles (in the families Meloidae and Rhipiphoridae) are among the very few insects that undergo hypermetamorphosis, an unusual type of holometabolous development in which the larvae change body form as they mature. Upon emerging from their mother's body, the young larvae, called triunguloids, have six legs and crawl around in search of a suitable host. In species that parasitize bees or wasps, a triunguloid usually climbs to the top of a flower and waits for a pollinator. When a host arrives, the larva jumps aboard, burrows into its body, and quickly molts into a second stage that has no distinct head, legs, antennae or other insect-like features. These larvae grow and continue to molt inside the host's body cavity, assimilating nutrients from the blood and non-vital tissues. After pupating in the host, winged males emerge and fly in search of mates. An adult female remains inside her host, managing to attract and mate with a male while only a small portion of her body protrudes from the host's abdomen. Embryos develop within the female's body, and a new generation of triunguloid larvae begin their life cycle by escaping through a brood passage on the underside of her body.

Adult male Strepsiptera are strange-looking insects. The head is small, with protruding compound eyes that look like tiny raspberries. The antennae are multi-segmented and have up to three branches. Front wings are reduced to small, club-like structures; hind wings are very large and fan-shaped."-- (N.C. State University Entomology Dept.)

Links to other sites

Aeneas Munane, Biology Major, University of Georgia, Athens.

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Updated: 2020-07-02 16:06:42 gmt
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