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FS ShieldForest Health Protection, Southern Region


Scolytus quadrispinosus Say

Importance. - The hickory bark beetle is reported to be the most serious insect pest of hickory in the United States. Several states have reported instances where thousands of trees were killed. Pecan and butternut are also hosts.

Identifying the Insect. - The adult is short, stout, black, almost hairless, and 1/5 inch (5 mm) long. The underside of the posterior is concave and has spines. The larvae are typically white or cream-colored, legless grubs, about the same size as the adults.

Identifying the Injury. - Dying leaves and twigs and trees with red foliage are the first evidence of attack. Short, vertical egg galleries with radiating larval galleries etched in the sapwood are good indicators of damage.

Egg gallry and larval mines

Egg gallry and larval mines. (Click for detail. JPG 34K).

Biology. - Adults appear in early summer and feed for a short time at the bases of leaf petioles and on twigs before attacking the trunks. Twenty to 60 eggs are deposited in egg galleries in the phloem. When nearly fullgrown, the larvae gradually angle away from the adult gallery. Before reaching maturity, they leave the phloem to pupate in the bark. Winter is spent in the larval stage and pupation occurs in the spring. There are usually two generations each year in the southern United States.

Control. - Control practices include felling infested trees over large areas and destroying the bark during winter months or storing infested logs in ponds. Insecticides can also be used.