The regeneration of pedunculate oak by shelterwood cutting causes profound ecological changes in the regenerated stands. In this paper, we studied how the pedunculate oak leaf miner community changes after shelterwood cutting with a short regeneration period and does the stand age influence the trend of seasonal variation in their diversity. Leaf miners were chosen because they are a very diverse group of insects closely tied to their host plant. For this reason, their community reacts to all changes to which their host plant is subjected. Three regenerated (5, 10, and 15-year-old) and one control (110-year-old forest) stand were selected in the studied area. A total of 28 species of leaf miners were recorded in them. Many rare species disappeared after shelterwood cutting, while frequent and abundant species experienced a decline in numbers. That led to a decrease in diversity, which was the lowest in the 5-year-old stand. The diversity of leaf miners began to increase in the older regenerated stands. The highest diversity was observed in the control stand. A period of 5 years is needed for the recolonization of approx. 40% of the leaf miner fauna, while 10 years is the recolonization period for approx. 60% and 15 years for approx. 85% of the above fauna. The trend of seasonal variation of the diversity of the pedunculate oak leaf miner community varied in stands of different ages. The diversity of oak leaf miners was the lowest in spring, whereas it increased until the middle of summer and then decreased in all the studied stands.