The 15 species recognised in this family are usually found on dead twigs or in leaf litter, where they presumably feed on fungal hyphae. Most adults are wingless. The males of Merothrips species have the dorsal surface of the head developed as a large glandular area, and males in this genus sometimes have the fore femora considerably enlarged. Unfortunately, no studies on the biology or behaviour of any of these species are available.
The antennae of Merothripidae species are eight or nine segmented, with the distal segments fully distinct from each other, and the sensoria on segments III and IV transverse or lenticular to slightly inflated. Sternite VII of females bears a pair of lobes each with two setae on the posterior margin, but these lobes are not easy to see unless slide-mounted specimens have been well cleared. This character state is shared with Melanthripidae species.
The head and thorax differ in structure considerably between species of Merothripidae. Most Merothrips species are minute and wingless, with the head unusually small and the tentorial bridge not developed, and the dorsal surface of the head of males is occupied by a large glandular area. In contrast, the larger species in the family are winged with a larger head in which the tentorial bridge is well-developed, and the males are not known.
Currently three genera are recognised in the Merothripidae (Mound & O’Neill, 1974). These are Damerothrips and Erotidothrips each with one species, and Merothrips with 13 species, see Mound’s Thysanoptera pages.
In contrast, (Bhatti, 2006) placed the first two genera into a separate family, Erotidothripidae, and placed three of the more distinctive species of Merothrips each into a separate genus.
Erotidothrips has been taken widely but rarely in the Old World tropics, including northern Australia, but Damerothrips is known only from Brazil. Most of the species of Merothrips are from the Americas, particularly the Neotropics, but M. floridensis is particularly widespread around the world, including southern Europe and Australia (Mound & O’Neill, 1974).
The Merothripidae is one of eight families recognised in the Thysanoptera suborder Terebrantia.
Members of this family are considered to retain some of the ancestral character states of Thysanoptera, particularly the presence in females of a pair of lobes each bearing two setae on the posterior margin of the seventh sternite. These structures are considered to represent a reduced eighth sternite (Mound et al, 1980), and they are otherwise found only in species of Melanthripidae.
This single family with three genera is interpreted by Bhatti (2006) as a superfamily, Merothripoidea, with two families: Erotidothripidae with two genera and Merothripidae with four genera. However, this classification emphasises structural differences rather than relationships, see Mound & Morris (2007).