The family consists of about 1,000 species in about 40 genera, of which most are tropical, although overall distribution is worldwide.

The first two abdominal sternites are fused, and in only some groups is a suture even visible.

As the name suggests, most adults are found on the undersides of the leaves of shrubs and trees, while larvae have been found in rotting wood, leaf litter, and nests of other insects.

As of 2002[update], the last publication of a world catalog of the family was that of Maurice Pic in 1910.

The oldest confirmed member of the family is Gryzmalia from the mid Cretaceous Burmese amber of Myanmar.