Wingspan 14–18 mm. A dark slate greyish moth with silver-tipped scales, often with a steal-blue metallic sheen. Five or more cream or white strigulae present on the costa interspersed with black. Bluish plumbeous striae arise from these costal strigulae, two of which edge the ocellus. Prominent black marks are present in the ocellus and beyond near the outer margin. Also a prominent black mark prior to the ocellus.

As the galls are always found high in the treetops, it is best to look for fresh-cut trees to find them.

The caterpillars need 2 years to develop. The young larvae live in the first year under the bark and bore tunnels into the bark of young larch twigs. As they develop further in the second year, resinous galls begin to form, sometimes swelling to twice or more the twig’s normal diameter. Each gall remains soft and spongy while it is occupied by a larva, which lives in a densely woven feeding tunnel and pupates later inside its walls in the spring of the second year. The pupa works its way out of the web tube before hatching.
The adults are rarely observed as they fly most of the time in the higher treetops. They come to light.

The larve lives on Larix decidua.

It inhabits areas where larch is abundant.