A Brief Spotlight on Scopariines

The moths of the Pyraloidea are perhaps one of the more under-appreciated sectors of lepidopteran diversity. With many thousands of species, they comprise a significant proportion of the order in terms of both taxonomic and ecological diversity. Nevertheless, with most species being small and dull in coloration, many Lepidoptera enthusiasts will tend to lump them in the too-hard basket for study. One subgroup of the pyraloids to which this issue definitely applies is the subfamily Scopariinae.

Scoparia spelaea, copyright Donald Hobern.

Close to 600 species of Scopariinae are known from around the world with the highest diversity found on tropical mountains and islands (Léger et al. 2019). They are mostly a mottled greyish in coloration, blending in among the rocks and tree trunks on which they settle during the day. Like other pyraloids, they have large palps that extend in front of the head; pyraloids as a whole are sometimes referred to as 'snout moths' in reference to the appearance this gives them. Forewing venation is characterised by clear separation of vein R₂ from R₃₊₄ and absence of CuP (Nielsen & Common 1991).

Meadow grey Scoparia pyralella, copyright Hectonichus.

The majority of scopariine species feed as larvae on mosses, living concealed within a slight silk web. A smaller number feed on dicotyledons or lichens. One New Zealand species, the sod webworm Eudonia sabulosella, has been known to cause economic damage to pasture during sporadic outbreaks. Other species generally do not cause significant impact to humans.

Eudonia lacustrata, copyright Tony Morris.

Identification of scopariines is notoriously difficult with many species closely approximating each other in pattern or exhibiting confounding intra-specific variation. The two largest genera Scoparia and Eudonia can only be reliably separated by examination of the genitalia. Two genera, the Indo-Australian Micraglossa and the Neotropical Gibeauxia, are distinguished by the presence of shiny golden scales on head, thorax and abdomen. With such significant challenges to their study, it would not be surprising if 600 species should turn out to be a marked under-estimate of their true diversity.

REFERENCES

Léger, T., B. Landry & M. Nuss. 2019. Phylogeny, character evolution and tribal classification in Crambinae and Scopariinae (Lepidoptera, Crambidae). Systematic Entomology 44: 757–776.

Nielsen, E. S., & I. F. B. Common. 1991. Lepidoptera (moths and butterflies). In: CSIRO. The Insects of Australia: A textbook for students and research workers 2^nd ed. vol. 2 pp. 817–915. Melbourne University Press: Carlton (Victoria).