Grid of sticky traps to catch Ips paraconfusus flying toward infested log (in blue square)
Byers, J.A. 1983c. Sex-specific responses to aggregation pheromone: Regulation of colonization density in the bark beetle Ips paraconfusus. Journal of Chemical Ecology 9:129-142.

Abstract-- About equal numbers of each sex of flying I. paraconfusus Lanier (Coleoptera: Scolytidae) were caught on traps several meters downwind from a male-infested ponderosa pine long releasing pheromone while a significantly different ratio of over 4 times more females than males were caught at the pheromone source. Females oriented directly to higher concentrations of colonizing males in a felled tree while males tended to land on the host in adjacent uncolonized areas. The attraction response of walking males to a 1:1:1 mixture of the synthetic pheromone components ipsenol, ipsdienol, cis-verbenol was reduced progressively at higher concentrations while female response continued to increase. These responses may function to regulate density of colonization and limit intraspecific competition.
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Chemical Ecology