I took these pictures at a lightsheet in Sam Houston National Forest. Fishflies, alderflies and dobsonflies are some of the strangest looking nocturnal critters you may run across. Large, soft-bodied, and wriggly, the aquatic larvae of some of these species are popular as bait with some fishers*. Male dobsonflies have hugely elongate mandibles, sometimes an inch long; however, these jaws are adapted for mating purposes and cannot inflict harm on humans. Other members of this family, including female dobsonflies and the aquatic larvae, can inflict a painful bite with their shorter jaws. While the larvae are active predators and scavengers which may live several years in the water, most of these insects live only briefly in their winged, adult form, and do not feed.
Male fishflies lack the imposing jaws of male dobsonflies, but can be distinguished from females by the extra fringe on their antennae (compare the picture of the male, above, with that of the female, below). In many insects, the responsibility for locating a mate falls to the males, who may have highly developed sensory organs for this purpose. These may include enlarged eyes, antennae, or ‘ears’ to detect signals from females. These male fishflies will use their antennae to pick up pheromones released by females.
These insects are members of the order Megaloptera (sometimes grouped as a suborder with Neuroptera) and the family Corydalidae.
*UNRELATED EDIT: My sources inform me that the correct term is ‘fishermen’ rather than ‘fishers.’ But what of the poor, overlooked fisherwomen? I suppose the term ‘fisherpeople’ does sound a bit off. From now on I’m calling them ‘fishpeople’ and have done with it.