The northern pine weevil is also sometimes referred to as the eastern pine weevil or deodar weevil. This species is a native insect pest of conifers and the adults as well as the larvae cause damage to their host plants. Adult weevils are present approximately in April or May (following pupation in March) and bore holes into the trunk, branches, or shoots of the host. A larger area may become hollowed out around the entrance holes from adult beetle feeding on the inner bark. The feeding damage done by the adults can, on young trees, weaken them enough to make the host suitable (or attractive) for egg laying by females. Adult weevils conduct maturation feeding on the shoots of the host plant, which may kill terminals. The pits created by the adults for both feeding and egg laying look similar, with the exception that egg laying pits are filled with chewed up vascular tissue (phloem). Females will preferentially lay their eggs low on the host plant, often in shady locations. Eggs hatch and larvae feed between the bark and wood, tunneling as they do. Larvae can be found in branches as small as 1/2 inch in diameter or in the root collar. Larval stages of this insect have been detected in host plants year round. Once mature, the larvae construct a "chip cocoon", a pupal chamber filled with wood shavings, within which they pupate. The entire life cycle of this weevil can take 1 to 2 years to complete, depending upon local climate.
This species is in the same genus as the white pine weevil (Pissodes strobi). The northern pine weevil is another example of a native North American insect that has been accidentally introduced to new locations outside of its native range. This includes in South Africa in 1942 where it has since caused significant damage to local pine plantations (Gebeyehu and Wingfield, 2003).
The northern (eastern) pine weevil is typically considered a secondary pest, and not commonly credited with weakening or killing otherwise healthy trees in North America. Prefers freshly cut stumps, windblown trees, or any size host plant that is alive but weakened or otherwise stressed or dying. These are the areas where adults will feed or lay their eggs. If a local population is high, even healthy or recently transplanted trees may be killed. Bark of main stem and lower branches of pine may be attacked. The adult beetles cause damage by feeding on the inner bark which may girdle the stem or twig. They puncture the bark of small twigs and leaders, eating a lot of the inner bark or wood in this area, which often causes the twig to break. Needles turn brownish-red and may curl. Often attracted to areas where Scotch pine Christmas trees have been harvested. Additionally, the northern pine weevil can vector a fungus - Fusarium moniliforme var. subglutinans. This particular fungus causes twig and branch dieback. The weevil may also facilitate other tree diseases.
Look for the typical first sign of infestation by this insect - discoloration or browning of foliage, especially on twigs or small branches. Visual monitoring may help locate entrance holes or egg laying locations. Sampling of infested branches and careful dissection may reveal larvae. A pheromone lure and traps for this insect may also be commercially available. Detecting peaks in adult emergence and flying may aid in planning chemical management decisions.
Remove stumps or other woody debris that act as breeding sites for this insect.
At least in Florida, natural enemies of the northern pine weevil are reported. These include a braconid wasp parasitoid (Coeloides pissodis) as well as predation from woodpeckers, disease, and competition with other insects such as those in the genus Ips (Thomas Atkinson et al., 1988).
Acephate (NL)
Azadirachtin (larvae) (NL)
Beauveria bassiana (NL)
Bifenthrin (NL)
Chlorpyrifos (N)
Clothianidin (NL)
Entomopathogenic nematodes (L)
Esfenvalerate (L)
Fenpropathrin (NL)
Gamma-cyhalothrin (L)
Imidacloprid (L)
Isaria (paecilomyces) fumosoroseus (larvae) (NL)
Lambda-cyhalothrin (L)
Metarhizium anisopliae (robertii) (NL)
Neem oil (NL)
Pyrethrin+sulfur (NL)
Tau-Fluvalinate (NL)
Stumps may also be treated chemically to deter mating.
Active ingredients that may be applied systemically include: azadirachtin (injection, soil drench) and neem oil (soil drench).
When used in a nursery setting, chlorpyrifos is for quarantine use only.
Make insecticide applications after bloom to protect pollinators. Applications at times of the day and temperatures when pollinators are less likely to be active can also reduce the risk of impacting their populations.
Note: Beginning July 1, 2022, neonicotinoid insecticides are classified as state restricted use for use on tree and shrub insect pests in Massachusetts. For more information, visit the MA Department of Agricultural Resources Pesticide Program.
