A Scots pine has fallen during a winter or spring storm and has damaged its roots so that some volatile monoterpenes float away to attract pine shoot beetles, Tomicus piniperda, which prefer these trees because they are less able to produce more resin than is a healthy tree. Resin is slightly toxic and can solidify and entrap bark beetles. Large trees with a horizontal silhouette as compared to a vertical one are also preferred by pine shoot beetles. The red barn in the background is a chicken rearing facility.

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