The aim of the study was to investigate the dependency between size reduction rate of thin pine stem fragments and population size of young Pityogenes bidentatus beetles, which developed on this material. Experimental plots were established in seven Pinus sylvestris stands. Thin stem tops were left on the ground after thinning. Some of them were cut into sections of 20, 50 and 100 cm. Results of the investigations showed that in case of thinning interventions in the spring-summer season more specimens of Pityogenes bidentatus are likely to develop on stems cut into short sections than it is the case when stems were left uncut.

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