trees used as food decoys in the fight against harmful forest insects, such as long-horned beetles, flatheaded wood borers, and the Hylesininae, that feed on phloem and leave their offspring under bark. There are standing trap trees, which are dried out by a circular debarking of the trunk, and fallen ones, which have been felled and left in the woods. Weak trees and trees of little value, as well as windfall, windbreak, and felled timber, are used as trap trees.
The trap trees are set on backings 15–20 cm thick in habitats of particular insect pests. The insects populate the trap trees, make passages under the bark, and lay their eggs. Before the larvae pupate or eat into the sapwood the bark is removed from the trees (standing trap trees are felled first) and burned or buried underground at a depth of at least 0.5 m. Trap trees are also used to study the growth of destructive insect populations.
REFERENCESpravochnik lesnichego, 2nd ed. Moscow, 1965.
I. I. ZHURAVLEV