Order Strepsiptera - Twisted-winged Insects

Probably sister to beetles(1) and used to be included in beetles by some workers(2)

Strepsiptera Kirby, 1813

~91 spp. in 14 genera of 6 families arranged in a single suborder (Stylopidia) in our area(3)(4)

~630 spp. in 43 genera of 15 families (10 extant) worldwide,(5)(4) arranged in 2 suborders, Mengenillidia (3 extant families) and Stylopidia (8 families)(6)(7)

Overview of our fauna of Strepsiptera

(* denotes taxa not yet in the guide)

Order Strepsiptera

0.5-4 mm(8)

Adult females are larviform/neotenic endoparasites; adult males are free-living, and their sole mission is to find and fertilize a female. They have reduced forewings and fan-shaped hind wings, branched antennae, and raspberry-like eyes, unique among living insects and somewhat similar to the eyes of trilobites.(7)

Key to families (adult males) by Kathirithamby & Taylor (2005).(3) See further taxonomic work by Pohl (2002) and Benda et al. (2022) on the overlooked separation of Stylopidae and Xenidae.

worldwide

obligate parasites of insects (hosts include members of 7 orders and 34 families)(7)

Apart from the adult males, the only free-living stages are the viviparous 1st instar host-seeking larvae(7); the larvae hatch as free agents from eggs laid on flowers. When a suitable host visits the flower, the larva attach itself to it and become parasitic.(8)

Benda D., Pohl H., Nakase Y., Beutel R. & Straka J. (2022). A generic classification of Xenidae (Strepsiptera) based on the morphology of the female cephalothorax and male cephalotheca with a preliminary checklist of species. ZooKeys, 1093: 1-134. (Full Text)

Balzer, Z.S. & Davis, A.R. (2019). Description of the Adult Male of Stylops advarians Pierce (Strepsiptera: Stylopidae). Zootaxa 4674 (4): 496–500 (Full Text)

Bohart, R.M. (1936). A preliminary study of the genus Stylops in California (part 1) (Strepsiptera/Stylopidae). The Pan-Pacific Entomologist, 12: 9–19. (Full Text)

Bohart, R.M. (1941). A revision of the Strepsiptera with special reference to the species of North America. University of California Publications in Entomology, 7: 91–160.

Bohart, R.M. & Irwin, M.E. (1978). A Study of Stylopization in the Bee Genus Dufourea. The Pan-Pacific Entomologist, 54: 98–102. (Full Text)

Hoffmann, M., Gardein, H., Greil, H., & Erler, S. (2023). Anatomical, phenological and genetic aspects of the host-parasite relationship between Andrena vaga (Hymenoptera) and Stylops ater (Strepsiptera). Parasitology, 150(8), 744–753. (Full Text)

Kathirithamby, J. (1989). Review of the Order Strepsiptera. Systematic Entomology, 14: 41-92 (Full Text)

Nakase, Y. & Kato, M. (2021). Bee-Parasitic Strepsipterans (Strepsiptera: Stylopidae) Induce Their Hosts' Flower-Visiting Behavior Change. Journal of Insect Science, 21(5): 1–5 (Full Text)

Niehuis, Oliver et al. (2012). Genomic and Morphological Evidence Converge to Resolve the Enigma of Strepsiptera. Current Biology 22: 1309-1313. (Full Text)

Pierce, W.D. (1909). A monographic revision of the twisted winged insects comprising the order Strepsiptera Kirby. Bulletin of the United States National Museum, 66: 1–232. (Full Text)

Pierce, W.D. (1918). The comparative morphology of the order Strepsiptera: together with records and descriptions of insects. Proceedings of the United States National Museum, 54: 391–501. (Full Text)

Pohl, H. (2002). Phylogeny of the Strepsiptera based on morphological data of the first instar larvae. Zoologica Scripta, 31(1): 123-134. (Abstract from publisher's website)

Pohl, H., & Beutel, R.G. (2005). The phylogeny of Strepsiptera (Hexapoda). Cladistics, 21: 328-374 (Full Text)

Pohl, H., & Beutel, R.G. (2008). The evolution of Strepsiptera (Hexapoda). Zoology, 111(4):318-38.

Fact sheet from Virginia Tech(9) (Web Archive) - taxonomy is out of date