Native to North America, the white pine weevil occurs throughout the range of white pine in eastern Canada. In white pine with recurring annual damage, wood quality is affected, reducing merchantable timber volume by sometimes up to 60%. Boxelder bugs. Insecticide should be applied to the terminal leader once it begins to warm up, somewhere around 25 to 65 growing degree-days base 50. It will absorb into the bark of the tree and offer both immediate control of active weevils … During the weevil life-cycle, different mortality factors affect the eggs, larvae, pupae and adults. This stability phase may last 10 to 20 years and is caused by equilibrium between the weevil population and the number of attackable leaders. PINE WEEVIL CONTROL. Check for weevil grubs in stored food, Monitor grains for mould and humidity, Choose insect-resistant foliage and trees, Store food in tightly sealed containers. It is also very effective for ornamental trees. Issued in furtherance of MSU Extension work, acts of May 8 and June 30, 1914, in cooperation with the U.S. Department of Agriculture. April 13, 2018. Feeding punctures made by the adult weevils can also damage the leader. White pine weevil or spruce leader weevil (Pissodes strobi) is a weevil in the family Curculionidae (weevils or snout beetles) in the order Coleoptera. To have a digest of information delivered straight to your email inbox, visit https://extension.msu.edu/newsletters. To emerge, the adults chew small round emergence holes through the bark. Reference to commercial products or trade names does not imply endorsement by MSU Extension or bias against those not mentioned. Infected leaders should be cut back at the level of the topmost whorl of unaffected branches. Physical control The white pine weevil prefers open-growing trees 1.5 to 8 m (6 to 25 feet) tall, in sunny locations. When mature, the larva is approximately 7 mm long, legless, and sli… Adults overwinter in the forest litter and, in early spring, they emerge when the temperature rises to 2-4oC. They will feed in the phloem under the bark for several weeks, pupate and then emerge as new adults around mid-summer. They remain on the host tree to feed until the temperature drops in fall, when they seek shelter in the litter to overwinter. If you had weevil damage last year and need to control the weevils, do it early this spring. Weevils also disperse by flying on warm sunny days. Jeffrey W. Dwyer, Director, MSU Extension, East Lansing, MI 48824. The adult weevils overwinter on the ground, protected and insulated by the litter (fallen needles). This is happening now around Lansing, Michigan, and will probably not happen until the end of April around Cadillac, Michigan. Other biological control agents, such as predators and parasitoids, play an important role in additional brood mortality. Eastern white pine, Engelmann spruce, jack pine, Norway spruce, scots pine, Sitka spruce, white spruce, Larvae into a terminal shoot of eastern white pine, Eggs in their natural position into a terminal shoot, Holes chewed by an adult in the stem for feeding and egg-laying, Appearance of a damaged terminal shoot on Norway spruce, Abnormal eastern white pine terminal shoot attacked, Abnormal terminal shoot on eastern white pine attacked par white pine weevil, Trees, insects and diseases of Canada's forests, Simple steps for controlling the white pine weevil, A simple effective tool for controlling white pine weevil and blister rust on Norway spruce and eastern white pine. A white pine weevil is also referred to as a spruce weevil or an Engelmann spruce weevil. To truly end your weevil infestation, you will need to the help of a professional pest control service. Studies have shown, however, that in Norway spruce, the impact on volume productivity can be negligible when the trees reach commercial size. Those eggs will hatch within a few weeks and the larvae chew their way through the bark. If you need to control white pine weevil, your best opportunity is early in spring. In western Canada, its distribution coincides with that of various species of spruce. The first symptom of weevil attack is resin oozing from small (0.5-1.0 mm) feeding punctures in the spring. Use a persistent product because the adult weevils don’t all warm up at the same rate. This information is for educational purposes only. Each time a female weevil makes a feeding wound on the terminal, she lays one to four eggs in the wound. In both cases, insecticide selection depends on the product label. This resin originates from special structures called resin canals found in the bark of the leader. It will absorb into the bark of the tree and offer both immediate control of … Indeed, the weevil's love of spruce is exemplified by its alternate common name, Engelmann Spruce Weevil, or simply Spruce Weevil. They crawl up the trunks of nearby host trees to the terminal shoot and begin to feed before mating. Michigan State University Extension programs and materials are open to all without regard to race, color, national origin, gender, gender identity, religion, age, height, weight, disability, political beliefs, sexual orientation, marital status, family status or veteran status. Although it occurs naturally in our forests, in eastern Canada, it is considered to be the most serious pest of white pine, jack pine and Norway spruce plantations. For more information, visit https://extension.msu.edu. The white pine weevil has only one generation per year, but the adults can live and continue laying eggs for several years. It has irregularly shaped patches of brown and white scales on the front wings. Insecticides labeled for application on spruce trees to control bark beetles or wood-boring beetles probably also would kill white pine weevils, but it is University of Idaho policy only to recommend products that specifically include both the target plant (spruce trees) and the target pest (white pine weevil). Symptoms are usually noticeable by late June. To contact an expert in your area, visit https://extension.msu.edu/experts, or call 888-MSUE4MI (888-678-3464). Since then, regular outbreaks have occurred. This is happening now around Lansing, Michigan, and will probably not happen until the end of April around Cadillac, Michigan. Grow evergreen trees under a canopy of 50% shade to make the leader shoots less attractive to the white pine weevil. Adult weevils are brown with white spots; they occur in spruce and pine ecosystems throughout Canada. This insect was first described in 1817 by W. D. Peck, a professor at Harvard University. Near the apex of the front wings is a large white patch. Centipedes. With the years, the insect became very common due to the increased number of plantations and the absence of control methods. If you can direct your spray to the leader (uppermost branch pushing upwards), and avoid spraying the rest of the tree, you will conserve beneficial species like predatory mites. At the end of their feeding period, the larvae burrow in the pith or directly under the bark, forming pupal cells lined with strands of wood chips. During outbreaks, the combined damage caused by adults and larvae results in reduced growth and usually in the total loss of the previous and current years’ terminal shoots. White pine weevil larvae kill the terminal leader and the top two to four years of growth on many varieties of spruce, as well as white and Scots pine trees.