Pyralidae

62.042 Thistle Ermine Myelois circumvoluta (Fourcroy, 1785)

Common

Similar species: Yponomeuta spp. are on average smaller moths with smaller spots in a different pattern. The Ethmia spp. are smaller moths with large spots arranged in a different pattern.

Forewing: 12.5 to 16mm

Habitats: Calcareous grassland and downland, field margins, wasteground, coastal sandy grassland and gardens.

Habits: The moth rests on thistles during the day. It is nocturnal and occasionally comes to light.

Foodplant: The larva feeds in the heads of Spear Thistle, Woolly Thistle, Cotton Thistle and sometimes Common Knapweed or Greater Burdock. It prefers the larger plants. In the autumn it mines down into the pith in the stem, where it forms extensive galleries (often feeding gregariously). It overwinters in the stem. In the spring it cuts an exit hole in the dead stem and pupates in a cocoon near the exit.