Very little is known of the biology of this interesting family. A few of the well known, widely distributed species, such as Scenopinus fenestralis and S. glabrifrons, have well documented life histories and have been associated with their hosts. From the meager records that are available, it is clear that the larvae of the Scenopinidae are all predacious on other insects. A number of species are predacious on the larvae of dermestids and have been commonly collected at the windows of storehouses, feed mills, and museums. Members of the genus Pseudatrichia have been reared from the nests of wood rats, where they were feeding on the larvae of fleas and lice. Several species have been taken as larvae or pupae from the nests of birds and reared out. Members of the genus Belosta from the western United States have been associated with bark-infesting beetles attacking pines and hardwood, and one species has been taken from a termite nest. The members of the genus Prepseudatrichia from Africa have all been reared from larvae collected in the wood of Acacia and Sterculia attacked by buprestid larvae.
Information concerning the habitat of the larvae or the hosts on which they feed has been recorded for less than ten percent of the known species of Scenopinidae. From the meager records at hand, however, some important clues to possible areas of concentration are indicated. Among the more obvious localities are: where dermestids occur, such as grain storages, warehouses and museums; birds' nests, particularly those occupied for relatively long periods of time; the nests or dens of animals; scar wood or under bark attacked by wood boring larvae; and the nests of termites.
The larvae are elongate, light bodied, hard, smooth, and wormlike with an elongate, pointed, strongly sclerotized, yellow head. When these larvae are found they should be maintained with the host culture, which should be held for a month or two after the emergence of the host adult, as the Scenopinid adults do not emerge until the next generation of the host has begun development. The pupae of the Scenopinidae appear very spiny, particularly along the abdominal segments.
The scarcity of specimens in most collections appears to be the result of failure to collect in the right place at the proper time. Most of the specimens observed have been obtained by sweeping foliage or flowers which strictly limits the chances of contact. The adult period appears to be relatively short in most cases and occurs at a regular time each year. There is good evidence that in areas with uniform plant or animal associations, large numbers of adults are present at the same time. In one instance, in California, over 150 specimens of a single species were taken on a two-day period along a distance of more than 100 miles. Other extensive series have also been seen that were taken in a short period by field crop inspectors sweeping the same crop over an extensive area. In other instances, members of the same species have been taken at the same locality in successive years on about the same date. The use of some permanent type of trap such as a Malaise trap would probably result in better sampling than that accomplished by most collectors with hand nets.