Strepsiptera-Infected Paper Wasp

Strepsiptera-Infected Paper Wasp
Order Hymenoptera – Ants, Bees, Wasps
Live adult Strepsiptera infected Polistes
paper wasps photographed in the wild.

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Strepsiptera infected Polistes
Strepsiptera – infected paper wasp
The anterior abdomens of two female Strepsiptera in the family Stylopidae protrude from under the abdominal segments of a paper wasp in the genus Polistes. Female Strepsiptera thus provide access to adult males for purposes of reproduction, which is accomplished by a process known as hypodermic insemination. In this instance, the insects are acting as endoparasites, that is, living inside the host's body.

Commonly called twisted wing parasites, these insects are mostly internal parasites of other insects. Males differ greatly from females in structure. Males have wide heads with compound eyes and fan-shaped antennae. Their forewings have evolved into clublike structures and the hind wings are membranous and without venation. Females are without legs, wings, antennae and often eyes. They remain inside the host throughout their lives. 

Twisted wing 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.

Video: paper wasp nest construction excerpt from the BBC's Life in the Underbrush
Wasps that construct nests made of a papery material are commonly called paper wasps. The nests consist of a single upside-down layer of brood cells. There are 22 species of paper wasps in North America and about 700 species world-wide. Most are resident in the tropics of the western hemisphere. The two most common paper wasps in the American midwest are Polistes dominulus, an introduced species, and Poliste fuscatus, the native "golden paper wasp." It is my opinion, after 5 years of careful field work and observance, that dominulus is replacing fuscatus, at least in the environs of DuPage County, Illinois.

Most paper wasps measure about 2 cm (0.75 in) long and are black, brown, or reddish in color with yellow markings. Paper wasps will defend their nest if attacked. Adults forage for nectar, their source of energy, and for caterpillars to feed the larvae (young). They are natural enemies of many garden insect pests.

The small nests of paper wasps, built of a fast-hardening mass of chewed-up wood pulp and saliva by a team of several females, consist of a single, circular comb with uncovered hexagonal cells. In paper wasp society, the female who began the nest-building dominates her workmates once the comb is completed. [1]

Strepsiptera infected Polistes
The nests of most species are suspended from a single, central stalk, or pedicle, and have the shape of an upside-down umbrella. Some tropical species make nests that hang in a vertical sheet of cells. Plant and wood fibers are collected by the wasps, mixed with saliva, and chewed into a paper-like material that is formed into the thin cells of the nest. The nests are constructed in protected places, such as under the eaves of buildings or in dense vegetation.

The colony is founded in early spring, soon after the queens emerge from hibernation. As the colony matures, males and the next year's queens are produced. These queens mate with males and are the only members of the colony to survive through winter. In late summer or fall, the founding queen, workers (sterile females), and males all die. The newly mated queens hibernate, in piles of wood, in vegetation, or in holes. The following spring they emerge and begin the cycle anew. A similar life cycle is found in bumble bees.


  1. Les Line, The Audubon Society Book of Insects (Harry N Abrams, 1983).

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Order Hymenoptera: Bees, Wasps, & Ants

Hymenoptera (Latin for membrane wing) is a vast assemblage of insects second only to Coleoptera (beetles) in the number of described species. Hymenoptera number some 115,000 species – of which 18,000 live in North America. Hymenopterans inhabit a wide variety of habitats, and show an incredible diversity in size, behavior, structure and color. Insects & Spiders | Bees & Wasps Index | Bees & Wasps