Abstract
The number of beetles landing was assessed for logs of Quercus serrata bored by male Platypus quercivorus with different densities in field. The number of both male and female beetles collected by adhesive traps set over logs correlated to the number of entry holes bored by the males until the 11th day of the investigation, but it tended to be density-independent at large number of entry holes. This result suggested that the effect of attractiveness of male's entry hole was limited against its number. After the 11th day, the number of collected beetles was greatly reduced, and did not correlate to the number of entry holes. Only one entry hole was bored by a landed male additionally among all logs investigated in the study period. A few holes had the main gallery bored after mating, and no beetles lived in all holes of all logs, which were cut open on the 28th day. These results suggest that when only a few males bore into a tree or a log which has been attacked en masse and on which a large numbers of males and females are landing, the number of males and females landing will decrease quickly and the attack will end, because all single males in holes will have mated, died, or left the holes and the attractiveness declines.
