legs, and eyes, but have a well sclerotised cephalothorax (fused head and thorax). Adult female mengenillids are wingless but are free living and somewhat mobile with legs and small eyes, this is probably also true for the bahiaxenids, though this has not been observed. Larvae Newly hatched primary (first instar) larvae are on average in length, smaller than many single-celled organisms. They are highly mobile with well developed stemmata eyes, which are able to distinguish color. The underside of the body is covered in minute hair-like structures (microtrichia), which allow the larvae to stick to wet surfaces via capillary action. At the back of the body are well developed large bristle-like cerci, which are attached to muscles, which allow the larvae to jump. The tarsal segment of their legs have structures which allow them to cling to their hosts. Later larval instars which develop inside the host are completely immobile. Life cycle Virgin females release a pheromone which the males use to locate them. Mating at least in some species is polyandrous, where the female mates with more than one male. In the Stylopidia, the female's anterior region protrudes out between the segments of the hosts abdomen. In all strepsipterans the male mates by rupturing the female's cuticle (in the case of Stylopida, this is in a deep narrow fissure of the cephalothorax near the birth canal). Sperm passes through the opening directly into the body in a process called traumatic insemination, which has independently evolved in some other insects like bed bugs. Strepsiptera eggs hatch inside the female, and the planidium larvae can move around freely within the female's haemocoel; this behavior is unique to these insects. The offspring consume their mother from the inside in a process known as hemocelous viviparity. Each female produces many thousands of planidium larvae. The larvae emerge from the brood opening/canal on the female's head, which protrudes outside the host body. Larvae have legs and actively seek out new hosts. Their legs are partly vestigial in that they lack a trochanter, the leg segment that forms the articulation between the basal coxa and the femur. The larvae are very active as they only have a limited amount of time to find a host before they exhaust their energy reserves. These first-instar larvae have stemmata (simple, single-lens eyes). When the larvae latch onto a host, they enter it by secreting enzymes that soften the