Comparison of beetle samples captured by traps with those of flowers in a broad-leaved forest

Beetle samples were compared between catches by traps and those on flowers in a Japanese beech (Fagus crenata Blume) forest, in Minakami, Gunma Prefecture, Japan. White plastic traps (Sankei Chemical Co., Ltd.) equipped with benzyl acetate were set out for a month from July 23 to August 23, 1993, and all beetles captured were collected every six days. During six days from August 10 to August 16, beetles were captured with traps and on wild flowers (Aruncus sylvester Kostel andAngelica polyclada Franch) at three hour intervals. Over the month, the traps captured 1,677 individuals of 73 species of 20 families, which included 16 (89%) species captured on flowers in the six-day period. Over the six days, the traps captured 327 individuals of 21 species of 12 families, compared with 685 individuals of 18 species of 5 families on the flowers; all of the families and nine (50%) species of beetles taken on the flowers were also captured by the traps; all of the species with more than five individuals captured on the flowers were also trapped. This suggests that capture by traps might sufficiently cover the beetle fauna on flowers. The number of species and individuals, as well as their changing patterns, however, varied more irregularly during the six-day period with the traps than with those on the flowers. A part of this paper were presented at the 46th meeting of the Kanto Branch of the Japanese Forestry Society (1994) These English titles are tentative translation by the authors from the originals