Wingspan male 12.5–14.5 mm, female 13.5–16.0 mm. In external characteristics, this species differs in its more black-gray color and more compact shape than Cydia pactolana, which is more light brown to olive brown. On the underside of the rear wing, a lighter spot is present in Cydia pactolana, which is missing in C. grunertiana.

In spring the larva is about 10-12 mm long, yellow or greenish-whitish and often with a reddish tinge. A brown head with a darker V-shaped mark and two dark spots on each side. The prothoracic plate, which is divided in the middle, is brown, anal plate light brown.

The female lays the eggs on the trunks of 15–30 year old Larix sp., mostly between 1 and 3 metres above the ground. Trees growing on sunny sides of a plantation are preferred.
The larva bores in the bark, generally just below a whorl of side branches. The bark swells and ejected frass becomes mixed with extruded resin.
The caterpillar lives under the bark in a short, densely woven feeding tunnel and hibernates at a young stage. Pupation takes place in April/May in the larval habitation at the top of the feeding passage, directly behind the cap of drill dust.
The adults come to light.

The larva lives under the bark of Larix.

Plantations and areas where the food plant grows.