Gadira petraula

Key Features

Gadira petraula is a small moth (Lepidoptera: Crambidae).
The wingspan is 16.5–20 mm for males and 9.5–11.5 mm for females.
The forewings are white, tinged with greyish and irrorated with blackish. The hindwings are grey, but darker posteriorily and with a pale line just before the hindmargin.
It is very similar to Gadira leucophthalma, and on Banks Peninsula the two species can be found together.
The forewing dorsum (trailing edge) is mostly unicolorous whitish to grey in G. leucophthalma, whereas it is patterned in grey and black in the slightly smaller G. petraula.
Gadira petraula has a short-winged female in contrast to G. leucophthalma.

Gadira petraula is found in the northeast of the South Island as far south as Banks Peninsula.
It inhabits rocky places from steep rock faces to mountainous rocky ridges and pavement, all with a cover of lichens (on whch the lavae feed).

Loss of habitat due to earthquakes.
Disturbance of habitat and fragmentation of populations as a result of road-making, farming practices and stock rubbing against rocks.
The flightless female has limited dispersal ability.

This species is difficult to monitor due to its rarity.
A standardised count of larval feeding signs, using the conspicuous webbing of the mature larvae as an indicator, can be used.
Undertake monitoring in September.

Landcare Research Threatened species Factsheet.
Patrick B.H. and Dugdale J.S. 2000. Conservation status of New Zealand Lepidoptera. Science for Conservation 136. Department of Conservation, Wellington. 33 pp. Link.