[ Back to Insects ] [ http://www.DigitalArborist.com ]

FS ShieldForest Health Protection, Southern Region

PALES WEEVIL,

Hylobius pales (Herbst)

and

PITCH-EATING WEEVIL,

Pachylobius picivorus (Germar)

Importance. - In the South, reproduction weevils are the most serious insect threat to newly planted pines, particularly on recently cut-over sites. The pitch-eating weevil is more common along the Gulf Coast. Feeding has been reported on most coniferous species, and all species of southern pines are susceptible to attack. Seedling mortality in plantations has been recorded as high as 90 percent, and 30 to 60 percent mortality is not uncommon.

Identifying the Insect. - Adult weevils are oblong, robust, black to reddish brown, and about 1/2 inch (12 mm) long. The wing covers have small, scattered patches of yellowish hairs. The pitch-eating weevil appears darker because the hairs on the wing covers are sparser and shorter.

Identifying the Injury. - Adult weevils feed on the tender bark of seedlings, twigs, or larger trees. Small, irregular feeding patches in the bark are characteristic of weevil damage. Heavy feeding may girdle the stem, causing wilting or death. Feeding below the root collar and on the roots is common.

Biology. - Adult weevils are attracted by the odor of fresh pine resin, and quickly invade recently logged areas. After mating, eggs are laid in lateral roots of fresh pine stumps. Eggs hatch in approximately 5 to 10 days. Larvae feed on the inner bark tissue of dead roots. Full-grown larvae construct a chip cocoon in the wood and pupate. The time spent in the pupal stage lasts from a few weeks to several months, depending on the temperature. Adult weevils are found year round, usually within flying distance of any pine cutting area. There may be two generations per year.

Control. - The insect can be controlled by delaying planting for one planting season in areas cut over after July, or by treating seedlings with a registered insecticide. Reducing the size of clear cuts prevents large populations of weevils from moving enmasse into new cutting areas.


Adult feeding

Adult feeding. (Click for detail. JPG 33K)