Hodges (1998) defined this family by three apomorphies of the larva: segments A1-8 with a pinaculum ring around SD1; presence of a pore posterior or ventroposterior of SD1, and segments A3-7 with secondary SV setae. Xyloryctidae is worldwide in distribution with more than 1200 species in 86 genera (Hodges, 1998). The family includes two subfamilies: Xyloryctinae and Scythridinae.
This subfamily can be defined by the autapomorphy of the abdomen having a band of spiniform setae on the posterior areas of terga 2-6. In addition, the antenna lacks a pecten and in males, is ciliate or pectinate, a frenulum is absent, the gnathos is fused with the tegumen laterally, the juxta is present, and the forewing has CuP present. The pupa has abdominal terga with a crenulate ridge near the anterior margins, becoming spined in some species. Two species of Thyrocopa, endemic to Hawaii, are wingless and have a jumping behavior (Medeiros, 2008).
Xyloryctinae includes more than 500 species in 60+ genera, with the highest diversity in the Indo-Australian Region, but with species also occurring in sub-saharan Africa and Polynesia (Scoble, 1992; Hodges, 1998).
Larvae feed on hosts in 21 plant families, including lichens, but almost half of the known hosts are species in Proteaceae and Myrtaceae (Hodges, 1998). Larvae live in concealed shelters or galleries made of silk and debris or soil. Larvae of some species tie leaves or bore into bark or wood of branches, and others drag leaves into their burrows (Scoble, 1992).
References: Common (1990), Duckworth (1973), Hodges (1978), Medeiros (2008), Moriuti (1982), Powell (1980), Zimmerman (1978).
This subfamily has an ankylosed aedeagus, antennal pecten present and ocellus (when present) separate from the eye. In addition, Scythridinae lacks a transtilla (in contrast to Chimabachidae), the juxta is present, the abdomen sternum 2 has paired apodemes but lacks paired venulae, and the abdominal terga lacks spiniform setae. The male genitalia are highly modified by reduction and fusion of structures in some species. The female genitalia have the ductus seminalis arising broadly from the posterior part of the corpus bursae (Hodges, 1998). The wings are narrow and some species are brachypterous (Landry, 1991). The larvae have secondary setae, especially at the bases of the prolegs.
Scythridinae occurs worldwide and includes more than 700 species in 26 genera (Hodges, 1998), but a large number of new species remain undescribed (Landry, 1991).
Adults of many species are diurnal and can be found in flowers of hosts or on substrates near the host (Landry, 1991). Larvae feed externally on buds and leaves within weak webs on more than 20 families, and some species are leafminers on grasses (Scoble, 1992).
References: Bengtsson (1984), Clarke (1965), Falkovitsch (1981), Hodges (1998), Landry (1991), Powell (1976a, 1980), Stehr (1987).