The Characteristics of the Insect Order Strepsiptera

The insect order Strepsiptera consists of over 600 species. They are fairly unique in that the female insect is parasitic, primarily infecting bees, wasps, cockroaches, leafhoppers, and silverfish.  She is an endoparasite, living inside the host body but does not feed off the host organs. With the exception of one family in this order, the female remains in a larval state for life and never leaves her host.

In contrast, the adult male is a free living insect that looks similar to a small fly with one pair of functional wings. The male has a lifespan of about five hours, seeming to exist solely for the purpose of reproduction.  He spends his short life searching for the female. He is attracted to the female because she releases a strong pheromone to signal her location and readiness for mating.

Mating is possible because the anterior region of the female remains outside the hosts body, accessible to the male. The fertilized eggs hatch inside the female and the larvae make their way to the outside world by traveling through a brood canal in the anterior of the female. They attach themselves to the exterior of the host insect and remain there until they make contact with a host of their own. The process by which the larvae transfer to a new host is not known. One theory suggests that they drop off on to flowers and plants visited by the parental host and lay in wait for a new host to arrive. They may enter this insect as the permanent host, or may travel with this insect to its nest and infiltrate the larvae found there. Others believe that the eggs of some species do not hatch inside the female but rather, the female lays the eggs on a plant or flower where the larvae hatch and wait for a new host. The larvae have six legs and a functional eye when they are free living. A metamorphosis occurs once they enter the host. They lose their legs and take on a maggot-like appearance.

As for the host insect, while the Strepsiptera do not feed on its organs, the parasite does receive nourishment from its blood. This process does weaken the host insect. In many cases, the host will become sterile after being infected by the parasite. A host can be infected with more than one parasite, often having three or four. Their appearance may change after infection. They may take on some of the characteristics of the opposite sex, their color may fade and markings may become lighter.