Pales Weevil and Root Collar Weevil
Hosts, Life Cycle and Symptoms
(Hylobius pales) is a serious pest in southern Illinois and in the south especially in nurseries, Christmas tree farms and forests. They feed on pine and spruce as well as many other conifers. This insect seldom bothers landscapes since there is very little breeding material left around. 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. The adults feed at night and hide in the leaf litter during daylight. They over-winter 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 in the roots of fresh cut stumps of pine trees. Larvae feed in the roots for most of the summer. They emerge in the fall after pupating in the roots of the cut trees.
Northern pine weevil
This weevil has a similar life cycle to pales weevil except that the larva feeds under the bark of the aboveground stump portion. It causes the same type of damage as pales weevil.
Root collar weevil
Root collar weevil also has a life cycle similar to pales weevil. However, root collar weevil larvae feed under the bark at and below the soil line on living trees, causing the tree foliage to yellow and die. Adults cause the same type of damage as pales weevil.
Grind out the stumps of cut down conifers for pales weevil and northern pine weevil. Spray base of tree in mid May and mid August for pine root collar weevil. Remove debris from around the trunk before spraying. Check with your local land grant university (Cooperative) Extension Service for recommended insecticide.
Written by James Schuster, retired Extension Educator, Horticulture & Plant Pathology, and reviewed by Dr.Philip L. Nixon, Extension Specialist-Entomology, Department of Crop Sciences, University of Illinois at Urbana-Champaign.
Filed under plants: Evergreen Trees & Shrubs
Filed under problems: Insects Damage