Pissodes nemorensis
Authors: Integrated Pest Management Program, University of Georgia, 2020
Description
Immature stages: The legless larvae are white with a light amber to dark orange head. They can be 6-12 mm long when mature. The pupae are similar in size to adults, but are creamy white, darkening as they complete the developmental stage.
Adult stage: Adults have a long, curved snout and are reddishbrown to gray with two gray or white spots on their back. Adults are typically 6-8 mm long.
Biology
Life cycle: Adult deodar weevils are active in the fall and winter months. In the fall, adult weevils infest stressed trees, feed and mate. Females lay eggs while feeding in the inner bark. Larvae emerge from eggs and continue to feed in the inner bark where they make chambers commonly referred to as “chip cocoons”. Deodar weevils pupate in these cocoons from late winter to early spring. In spring from March to April, adult weevils emerge from pupation. Deodar weevils are usually inactive in hot summer months. There is one generation per year.
Damage
All native southeastern pines of all ages are susceptible to attack by the deodar weevil. Common hosts are loblolly, longleaf, shortleaf, slash, spruce and sand pines. Trees that are dying or extremely stressed by environmental conditions such as fire, drought, excessive cold, fusiform rust and wind damage are often attacked. Young pines in overstocked stands are also susceptible. Often, a deodar weevil infestation is in conjunction with a bark beetle attack. Damage includes foliage discoloration, with needles having a scorched appearance, particularly topmost branches. Small holes (0.4 mm wide) in shoots, often the most dominant branch. Shallow depressions or chambers in the sapwood with a layer of long yellowish-white wood fibers on top. Wounds created by the deodar weevil can allow the pitch canker fungus to enter infested stems.
Other vegetable crops injured include beet, cantaloupe, celery, cucumber, lima bean, lettuce, parsnip, pea, pepper, potato, snap bean, spinach, squash, sweet potato, and watermelon. Additional hosts are flower crops such as chrysanthemum, hollyhock, snapdragon, and sweet pea, and field crops such as cotton and tobacco. Larval feeding on foliage is usually initiated on mature leaves and can occasionally occur on the surface of mature fruit. Older larvae consume large irregular areas of leaves, characteristically leaving the larger leaf veins. About 90% of total defoliation occurs during the last two larval instars.
Management
Maintain tree vigor. Thin overstocked stands to reduce pest population size. Thin once tree growth falls below a 5% annual diameter growth threshold, as egg-laying females avoid pines growing at 5% or higher. Applying an approved insecticide on recently attacked and neighboring trees is also a viable control option. An insecticide application is not very practical on infested trees in a rural forest stand.