Females without wings or feet, parasitic. Males possessing the posterior pair of wings, which are large, membranous, and folded longitudinally like a fan. The anterior pair of wings rudimentary, represented by a pair of singular twisted organs, jaws rudimentary.

The Strepsiptera constitute a small order, which includes certain parasites of minute size, found on Bees and other Hymenoptera. The female is a soft vermiform grub, without feet or wings, but with a horny head, which it protrudes from between the abdominal segments of its host. The larvae are active, and possess six feet; whilst the males (fig. 193) are winged, and fly about with great activity.

Fig. 193. - Strepsiptera. Stylops Spencii, greatly-magnified (after Westwood).

The Strepsiptera are now very generally regarded as an anomalous and degraded group of the Coleoptera.