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Oak Pests - A Guide to Major Insects, Diseases, Air Pollution and Chemical Injury

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Anelaphus villosus

Importance. -- The twig pruner occurs throughout the East. It prefers hickory and basswood but also attacks oaks. Larvae bore into the stems and cut off or prune twigs, terminals, and branches about .25 to 1 inch (6 to 25 mm) in diameter. Severe pruning adversely affects tree form and the aesthetic quality of ornamental plantings, and creates clean-up problems.

Identifying the Insect (figure 27a). -- Larvae are cylindrical, white, and measure about .5 to .8 inch (12 to 21 mm) long at maturity. Adult beetles are gray mottled.

Identifying the Injury (figure 27b). -- During the summer, fall, and winter, pruned twigs (with leaves attached) 12 to 40 inches (30 to 100 cm) long litter the ground under infested trees. The end of the severed twig presents a smoothly cut surface. Split the pruned twigs to reveal the larva.

Biology. -- Adults emerge during spring and deposit eggs in small twigs. The larva burrows down the center of the stem and severs the twig, which falls to the ground, in late summer or fall. Pupation and adult emergence occur the following spring. There is one generation per year.

Control. -- Collect and burn severed twigs during the fall and winter. Natural enemies help control the twig pruner.


Figure 27a

Figure 27b

Figure 27. -- (a) Ends of girdled twigs, tunnel, and larva of twig pruner; (b) young tree with top recently severed by twig pruner.
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