University of Illinois Extension

University of Illinois Extension

Hort Answers

Insect Damage

Pine Root Collar Weevil
Hylobius radicis

Pine root collar weevil adult twig damage on pine. P. Nixon.
Pine root collar weevil adult twig damage on pine. P. Nixon.
2 (1 = rare 5 = annual)
3 (1 = very little damage 5 = plants killed)
The insects feed on pine and spruce as well as many other conifers.

Plants Affected
This insect seldom bothers landscapes because this insect primarily attacks younger trees with trunks from one to four inches in diameter. The adult chews small holes in the bark of small twigs and branches. Bark may fall away in the chewed areas. On large trees the chewing is usually near the end of branches. Needles and shoot beyond the chewed area often die, leaving reddish dead tips, which is considered unsightly. In Illinois, this insect appears to be more common insandy soils.

Life Cycle
The adults feed at night and hide in the leaf litter during daylight. They overwinter as adults and emerge from late April to June, depending on location. Adults may survive more than one "season" (fall through the following fall). It is not uncommon that they survive two "seasons. Adults lay their eggs under the bark just above and below the soil line of live trees. The larvae feed under the bark at and below the soil line on living trees, causing the tree foliage to yellow and die. They emerge in the fall after pupating in the soil near the trees.

Spray base of tree with a recommended insecticide in mid May and mid August. Remove debris from around the trunk before spraying.

Related Resources
Home, Yard & Garden Pest Guide
Illinois Commercial Landscape and Turfgrass Pest Management Handbook
U of IL - Distance Diagnosis through Digital Imaging
U of IL - Plant Clinic