Zoraptera, commonly known as angel insects, are a small and often overlooked order of insects. With only about 50 described species, they are among the least diverse insect groups globally. These minute creatures have intrigued scientists due to their unique characteristics and obscure evolutionary relationships.
Physical Characteristics
Angel insects are soft-bodied and measure under 3 millimeters in length, resembling small termites. They possess nine-segmented antennae with a beaded or moniliform appearance. Chewing mouthparts are adapted for processing various food sources.
Zoraptera have two distinct adult forms within the same species. One form is pale, wingless, and lacks both compound eyes and simple eyes (ocelli); this is the more commonly encountered morph. The other form is darker, possesses both compound eyes and ocelli, and has two pairs of membranous wings with reduced venation. These wings can be shed at a basal fracture line, similar to how termites detach their wings.
Habitat and Distribution
Angel insects inhabit moist, decaying organic matter, such as rotting wood, under loose bark of dead logs, and within leaf litter. They are also found in piles of decaying sawdust or in association with termite nests. Their presence can sometimes indicate a specific stage of wood decomposition.
Zoraptera are predominantly found in tropical and subtropical regions, though some species extend into warmer temperate zones. They have been recorded on all continents except Antarctica and Europe. While not present on mainland Australia, a species exists on Christmas Island. Their greatest species diversity occurs in the Neotropics, with populations also found across North America, Southeast Asia, Africa, and the Pacific islands.
Behavior and Diet
Angel insects live gregariously, forming small aggregations or colonies ranging from a few dozen to over a hundred individuals. Despite living in groups, they do not develop the complex social structures seen in insects like termites or ants. Some species, such as Centrozoros gurneyi, display a social hierarchy among males, involving behaviors like head-butting during dominance contests.
Their diet consists primarily of fungal spores and hyphae, which they scavenge from their decaying wood and litter habitats. They also prey on arthropods, including mites, collembolans, and small nematodes. In controlled environments, angel insects consume yeast and crushed rat chow, and cannibalism has also been recorded.