Scorpion Flies. This is a relatively small order of insects that a thought to be closely related to fleas. They are somewhat fly-like in appearance, being small to medium-sized insects with long slender bodies and narrow membranous wings. Most breed in moist environments such as leaf litter or moss, and the eggs may not hatch until the wet season arrives. The larvae are caterpillar-like and mostly feed on vegetable matter and the non-feeding pupae may pass through a diapause until favorable weather conditions occur. Early Mecoptera may have played an important role in pollinating extinct species of gymnosperm before the evolution of other insect pollinators such as the bees. Adults of modern species are overwhelmingly predators or consumers of dead organisms; they are the first insects to arrive at a cadaver, making them useful in forensic entomology.
Various courtship behaviors have been observed among mecopterans, with males often emitting pheromones to attract mates. The male may provide an edible gift such as a dead insect or a brown salivary secretion to the female. Some boreids have hook-like wings which the male uses to pick up and place the female on his back while copulating. Male panorpids vibrate their wings or even stridulate while approaching a female.
Hangingflies (Bittacidae) provide a nuptial meal in the form of a captured insect prey, such as a caterpillar, bug, or fly. The male attracts a female with a pheromone from vesicles on his abdomen; he retracts these once a female is nearby, and presents her with the prey. While she evaluates the gift, he locates her genitalia with his. If she stays to eat the prey, his genitalia attach to hers, and the female lowers herself into an upside-down hanging position, and eats the prey while mating. Larger prey that is offered result in longer mating times. In one reported species, prey 0.12 to 0.55 inches long give between 1 and 17 minutes of mating. Larger males of that species give prey as big as houseflies, earning up to 29 minutes of mating, maximal sperm transfer, more oviposition, and a refractory period during which the female does not mate with other males: all of these increase the number of offspring the male is likely to have.