The black-dotted groundling Stenoleсhia gemmella L. hibernate in the egg stage under the squama of buds. Eggs measure 0.50х0.23 mm in size. Caterpillars burst at expansion of buds of an oak. The stage of a caterpillar is 1.1-1.5 months, with the width of the head capsule of larvae at the six age stages being 0.04, 0.19, 0.22, 0.38, 0.46, and 0.60 mm. A caterpillar of the first age damages the central vein of a young leaf in a bud, after the second molting the caterpillar damages the central part of one or several young shoots. Mortality of caterpillars does not exceed 31%. Pupates occurs in top or the mid-part of the gallery. Pupas of 4.4х1.2 mm in size develop for about two weeks, with the survival rate being equal to 59%. Duration of intensive flight of butterflies is about 10 days, the survival of butterflies is 90%, share of females is 57%, and fecundity is about 80 eggs. In years with the greatest number of pests, up to 30% of all shoots of the current year and 12% of the leaves dry up. The loss of foliage Y (%) is associated with the proportion of damaged shoots (%) by the equation Y = 0.319x + 1.422. Damage to shoots occurs in all parts of the crown. Low-density plantations and free-standing trees are damaged more severely.