Destruction due to a white pine weevil is very distinctive. To truly end your weevil infestation, you will need to the help of a professional pest control service. If you have young pine trees and want to ensure they don’t get targeted by pine weevils or other wood borers, spray them each spring with MAXXTHOR EC. It has irregularly shaped patches of brown and white scales on the front wings. White pine weevil is the smaller of the two pests, measuring about ¼ inch (6–7 mm) long; males are slightly smaller than females. This is happening now around Lansing, Michigan, and will probably not happen until the end of April around Cadillac, Michigan. 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). Small oviposition punctures covered by blackish fecal caps can also be seen, usually near the top of the previous year's leader.Tree mortality due to the white pine weevil is rare, however. Damage from the pest was first reported in the early 20th century in eastern Canada. 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. Pruning should be done while the larvae are still active under the bark and before the emergence of the new generation of adults. The larvae are white, legless, C-shaped grubs with a medium brown head and several long, silken hairs on the body. Overwintering mortality of the weevil is considered a key factor in the reduction of the weevil population in white pine plantations. PINE WEEVIL CONTROL. This article was published by Michigan State University Extension. Apply these products at rates given on the label for bark beetles or borers. In young plantations, trees should be inspected annually as soon as they reach 1m, to ensure early detection of the pest. Damage from white pine weevil can be distinguished from other types of injury by the somewhat curled shape of the leader, sometimes referred to as a “shepherd’s crook” (see photo). The adult is a small rust-colored weevil that is about 4-6 mm long. The following year, pruning should be done to restore the shape of the tree. No single control method by itself can provide adequate pest suppression. When mature, the larva is approximately 7 mm long, legless, and sli… If you need to control white pine weevil, your best opportunity is early in spring. Direct control through the use of pesticides may be necessary but is not advised without first consulting a specialist in tree pest control. The white pine weevil has only one generation per year, but the adults can live and continue laying eggs for several years. How can the large pine weevil be controlled? Check out the MSU Fruit and Vegetable Crop Management Certificate Program! Effective management of the white pine weevil requires an integrated approach that ideally brings together biological, horticultural, and mechanical pest control methods with the judicious use of insecticides. Weevil adults could feed on the terminals for three weeks or perhaps longer. Use a persistent product because the adult weevils don’t all warm up at the same rate. During the summer, predation by larvae of the fly Lonchaea corticis may cause the death of up to 85% of the new generation. Is the weevil that you are dealing with the white pine weevil (Pissodes strobi) that feeds under the bark on the upper leaders of the conifer trees and that cause a "shepherds crook" to form and kills the new growth?If that is the pest, then it is too late to spray topical insecticides on the trees to prevent the weevils from putting the next generation of eggs under the bark. Diversification of the tree population can also prove effective. Issued in furtherance of MSU Extension work, acts of May 8 and June 30, 1914, in cooperation with the U.S. Department of Agriculture. Other biological control agents, such as predators and parasitoids, play an important role in additional brood mortality. Chemical Control (Planning Ahead) Conifers may be protected against white pine weevil in two ways: by spraying the tops of the trees in early spring or by making a fall application of a systemic insecticide. Native to North America, the white pine weevil occurs throughout the range of white pine in eastern Canada. Where habitat conditions are suitable for the weevil, outbreaks develop in pine or spruce regeneration after the overstory is removed by natural (fire, windthrow, bark beetle) or man-made disturbance (harvesting). This usually coincides with the ripening of wild raspberries around mid-July. It will absorb into the bark of the tree and offer both immediate control of … 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. pine weevil control (Table 1). Populations are monitored by the provincial departments.Damage is caused mainly by the larvae, which feed under the bark of the tree’s terminal leader. Centipedes. An alternative method for pine weevil suppression is the application of entomopathogenic nematodes to tree stumps harbouring developing pine weevils. The larval stage, which lives beneath the bark, is white with a distinct brown head. The white pine weevil has only one generation per year, but the adults can live and continue laying eggs for several years. Other pests related to Weevils . Insecticide should be applied to the terminal leader once it begins to warm up, somewhere around 25 to 65 growing degree-days base 50. Symptoms are usually noticeable by late June. Damage from white pine weevil can be prevented by spraying the upper trunk and terminals of spruce and pine in early to mid-April and again two weeks later with products that contain bifenthrin, permethrin or cyfluthrin. A basal soil drench with imidacloprid at this time may be too late to protect against white pine weevil this year. Infected ornamental specimens lose their aesthetic value. Winter mortality due to poor litter quality and ground predation was also observed in jack pine plantations. Those eggs will hatch within a few weeks and the larvae chew their way through the bark. The female lays her eggs in feeding cavities in the bark made with her rostrum. Physical control The white pine weevil prefers open-growing trees 1.5 to 8 m (6 to 25 feet) tall, in sunny locations. Dave Smitley, Michigan State University, Department of Entomology - If you need to control white pine weevil, your best opportunity is early in spring. An alternative treatment is basal application of imidacloprid (Bayer Tree and Shrub Insect Control) at the rate given for borers. It’s better to be a bit early than to be late with this application. They will feed in the phloem under the bark for several weeks, pupate and then emerge as new adults around mid-summer. 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. Reference to commercial products or trade names does not imply endorsement by MSU Extension or bias against those not mentioned. The adult weevils damage seedlings by chewing small holes on the stem above and below the ground. How can I prevent weevils invading? The curling effect is caused by more weevil larvae feeding on one side of the leader. The lateral branches on the whorl will compete for apical dominance. This resin originates from special structures called resin canals found in the bark of the leader. In the springtime, female weevils begin laying eggs and feeding on branch tips at the top of their favorite tree hosts. During the weevil life-cycle, different mortality factors affect the eggs, larvae, pupae and adults. Adult weevils are brown with white spots; they occur in spruce and pine ecosystems throughout Canada. MSU is an affirmative-action, equal-opportunity employer. For more information, visit https://extension.msu.edu. 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. If you had weevil damage last year and need to control the weevils, do it early this spring. White Pine Weevil (Pissodes strobi) is a native conifer pest with a wide host appetite. In western Canada, its distribution coincides with that of various species of spruce. With the years, the insect became very common due to the increased number of plantations and the absence of control methods. Check out the MSU Landscape and Nursery Management Certificate Program! Its host range includes Scotch, jack, red, pitch, and eastern white pines as well as Douglas-fir and all spruces. These extra leaders increase oviposition sites and food supply. Adults overwinter in the forest litter and, in early spring, they emerge when the temperature rises to 2-4oC. PINE WEEVIL CONTROL If you have young pine trees and want to ensure they don’t get targeted by pine weevils or other wood borers, spray them each spring with MAXXTHOR EC.