Three sticky traps of "hardware cloth" metal screen covered with Stickem special or Tanglefoot polymers that stick any insects that intercept traps. This shows the lower part of 12-m metal pole with traps every 1.2 meters. Catch of various bark beetles flying at the different levels was monitored in the spring. Note a second trap pole in distance at right. The traps on pole in foreground were at the center of an equilateral triangle with 3 other poles spaced 50 m away from center pole (which had baits inside each sticky trap that released attractive host tree monoterpenes, alpha-pinene, 3-carene, and terpinolene). The three poles at the apexes of the triangle were "passive", meaning they did not release chemicals but merely intercepted flying bark beetles to determine at which heights they fly and the densities.

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Images © 1996 by John A. Byers, Chemical Ecology.