Twisted-winged Insects

Strepsiptera

Classification

Phylum: Arthropoda
Subphylum: Hexapoda
Class: Insecta
Order: Strepsiptera

Pronunciation

How to pronounce Strepsiptera: //strɛpˈsɪptərə//

These audio files are automatically generated. While they are not always 100% accurate, they are a good starting point.

Images

Elenchus koebelei by W.D. Pierce (1881-1967). Used under a Public domain license.

Caenocholax fenyesi clean by Wytsman, Philogéne, 1866-1925. Used under a Public domain license.

Caenocholax fenyesi by Pierce, D.. Used under a Public domain license.

Coleopterida by derivative work: User:A. C. Tatarinov. Used under a CC BY-SA 4.0 license.

Meyers b5 s1008 b3 by Heinrich Morin. Used under a Public domain license.

Xenos peckii head closeup by Dongmin Keum, Kyung-Won Jang, Daniel S. Jeon, Charles S. H. Hwang, Elke K. Buschbeck, Min H. Kim & Ki-Hun Jeong. Used under a CC BY 4.0 license.

Summary

Strepsiptera, or twisted-wing insects, are a unique order of parasitic insects, predominantly characterized by their dual life cycle as free-living males and parasitic females. Their distinct morphological features and reproductive strategies set them apart from more commonly known insect orders.

Physical Characteristics

Adult males are 0.5-4 mm in size, with reduced forewings modified into halteres and fan-shaped hindwings. They have branched antennae and unique raspberry-like eyes resembling those of trilobites. Adult females are neotenic, lacking wings, legs, and eyes, but have a well-sclerotized cephalothorax.

Identification Tips

Key identification feature in adult males includes their palps modified into sensory structures and the distinct raspberry-like eyes. The presence of the halteres instead of typical forewings can also help in identifying them as Strepsiptera.

Habitat

Strepsiptera are obligate endoparasites often found in environments where their hosts (various insects) dwell, such as flowers where larvae seek their hosts.

Distribution

Approximately 630 species in 43 genera and 15 families worldwide, with representation in diverse ecological regions due to their wide range of insect hosts.

Diet

Adult males do not feed, while females are endoparasitic and feed on the host they inhabit. Larvae are host-seeking and require a living host to develop.

Life Cycle

The life cycle includes several stages: eggs hatch into free-moving larvae that seek hosts. Inside the host, they undergo hypermetamorphosis leading to legless neotenic females or mobile males. Mating occurs when males rupture the cuticle of females during traumatic insemination.

Reproduction

Females release pheromones to attract males for mating, which may involve polyandrous behavior. Females produce thousands of planidium larvae that emerge as the head protrudes from the host body.

Ecosystem Role

As parasites of other insects, they may influence host populations and behavior. Some can modify the behavior of their ant hosts to increase chances of transmission and mating.

Cultural Significance

Known as twisted-wing insects, they have limited recognition outside entomological circles.

Collecting Methods

Using light traps to collect nocturnal males.
Cages containing virgin females to lure males.

Preservation Methods

Standard insect preservation methods such as pinning and spreading.
Freezing and preserving in alcohol for genetic studies.

Evolution

Evolved approximately 300–350 million years ago, with the first appearances in the fossil record during the mid-Cretaceous. Molecular studies suggest they are closely related to beetles.

Similar Taxa

Misconceptions

Many people are unaware of the existence of Strepsiptera due to their obscurity and the misconception that they are closely related to more commonly seen insects like flies.