Taxonomy

Domain	Eukarya
Kingdom	Animalia
Phylum	Arthropoda
Subphylum	Hexapoda
Class	Insecta
Subclass	Pterygota
Infraclass	Neoptera
Order	Coleoptera
Suborder	Polyphaga
Infraorder	Cucujiformia
Superfamily	Curculionoidea
Family	Curculionidae
Subfamily	Molytinae
Tribe	Hylobiini
Genus	Pachylobius

Scientific Name

Pachylobius picivorus

Common Name

pitch-eating weevil

Author: H.C. Ellis, University of Georgia

The pitch-eating weevil Pachylobius picivorus (Germar) can be very destructive pests of young pines. All species of pines are considered susceptible to damage, and either insect may be an occasional pest of pines grown as Christmas trees.

Description

Adults of pitch-eating weevils are 10 - 12 mm and brownish-black with yellowish spots on the wing covers. The larvae of are typical weevil grubs. They are white with brown heads, legless and somewhat C-shaped. Mature larvae are 6 - 7 mm long.

Damage

The most serious injury occurs to small seedlings or to the branches of larger trees as a result of adult feeding. The weevils feed by chewing small, irregular holes in the bark. When feeding is heavy, the holes run together, effectively girdling small trees or the branches of larger trees. Even if the terminals of larger trees are not girdled, "flagging" or distorted terminals can result, making the tree less marketable. Damage is usually more serious in or near freshly cut timber areas.

Life History and Habits

In extreme south Georgia, adults may be active year-round, although numbers are normally low in winter. Adult weevils may also pass the winter in the soil or beneath ground litter around a tree. On emerging in the spring, adults feed on the bark of pine seedlings or the terminals and twigs of larger trees. Trees up to 1.5 cm in diameter are sometimes girdled and killed. The weevils usually feed at night and hide in the soil around trees during the day. Adults are attracted to freshly cut stumps or weakened pines. Females lay eggs beneath the bark, in the roots of stumps, dead trees or dying trees. Larvae hatch and feed primarily in the roots for six to eight weeks before pupating. The pupal stage lasts two to four weeks, depending on temperature. There are thought to be two generations per year in south Georgia.

Control

Adult feeding damage may be prevented by spraying young seedlings and twigs with an insecticide when adults emerge in the spring. Exact timing is best determined by examining twigs or terminals fro the small circular feeding holes which denote adult activity. Sprays may also be needed for adults emerging during the summer.

Avoid attacks by not planting Christmas trees in or near recently harvested areas and by destroying stumps and weakened dying trees quickly in or near plantings. If planting near a recently cut area cannot be delayed, dip young seedlings in an insecticide before planting to protect them against the weevils. If stumps cannot be pulled, treat them with an insecticide to reduce egg-laying by the adults.