White pine weevil: what the agencies record

This page reports what the official source says. It is not legal advice: ask the office named here. It does not identify what is wrong with any tree and does not say what should be done about one. The white pine weevil (Pissodes strobi) is a native insect of North America, and none of the three pages read lists it as regulated or notifiable. Each section names its source, all read on October 9, 2026. The parent page, insect pests of trees, compares it with the other pests on the list.

Names

Natural Resources Canada, called NRCan, gives the scientific name Pissodes strobi (Peck), the French name charançon du pin blanc, and the other common name spruce weevil. It lists Pissodes engelmanni and Pissodes sitchensis as synonyms and explains that the weevils once thought to attack Engelmann and Sitka spruce in the west are recognized as the same single species. It places the insect in the weevil family, Curculionidae.

Hosts and where it is found

NRCan calls it a widespread native insect of young pine and spruce trees, with a range that matches its main hosts: eastern white pine, jack pine, white spruce, Engelmann spruce and Sitka spruce. It says the distribution runs across Canada and south into the eastern United States to the northern forests of the mid-Atlantic and Lake States, and through the Pacific Northwest and Rocky Mountains to Colorado. Norway spruce, blue spruce and Scots pine are listed as secondary hosts, especially in Christmas tree and landscape plantings. Penn State Extension rates it the most destructive insect pest for eastern white pine across North America and adds Colorado blue, Norway and Serbian spruces, and Scots, red, pitch, jack and Austrian pines, and occasionally Douglas-fir as hosts. It says trees become susceptible at a height of about three feet and that the weevil prefers trees in direct sunlight. The University of Kentucky says the weevil can breed in a wide variety of spruces and pines.

What the sources say to look for

NRCan describes the adult as a dark brown beetle 6 to 7 millimetres long, covered in white and tan spotted scales, with the snout typical of weevils. Penn State gives 4 to 6 mm, rust-colored, with a large white patch near the apex of the front wings. NRCan says resin may flow in early spring from feeding pits the adults make on the leader just below the terminal bud, and that the larvae are white, legless and 9 to 10 millimetres when grown. Penn State describes glistening resin droplets on terminal leaders in late March and April as the first symptom, and larvae that are white with a distinct brown head. Kentucky also names pitch flow on terminal shoots as the first sign, followed by stunted new growth and wilting needles.

Both NRCan and Penn State describe the same end result. The larvae feed downward under the bark and girdle the leader, the leader above wilts and droops, and NRCan calls the resulting shape a shepherd's crook, "the unmistakable signature" of attack. By late summer the dead leader is riddled with round emergence holes.

Life cycle as the sources state it

NRCan and Penn State give one generation a year. NRCan says eggs are laid in feeding pits just below the terminal bud and plugged with macerated phloem, hundreds may be laid in a single leader, and larvae feed on the phloem before pupating in a chamber of wood shreds in the pith. Penn State says adults overwinter in the leaf litter, become active from mid-March through April, mate and lay one to five eggs per feeding wound from mid-April through early May, and that eggs hatch in about seven days. Larvae mature in mid to late July, and adults emerge in 10 to 15 days, usually in late July and August. NRCan adds that adults may live up to four years. Kentucky says adults winter in litter on the ground and that larvae bore downward in the cambium and pupate in late July.

Damage as the sources describe it

NRCan says attacks are most common on vigorously growing trees with leader diameters over 4 millimetres and heights under 6 metres, with attack rates falling after about 20 years, which makes the weevil a bigger problem in plantations, Christmas tree plantings and nurseries. It says that before large-scale logging in the late 19th century the weevil was a relatively harmless inhabitant of forest edges and gaps, and that open, warm plantations favored population increases. Damaged trees send up several new shoots, and the legacy of repeated attacks is crooked stems, multiple leaders and twisted tops decades later. Penn State says injury to eastern white pine and some spruces is usually confined to the leader grown the year before the attack, that damage on Scots pine and several spruces often runs down two or three years of growth, and that infested trees are seldom killed. It describes a permanently crooked or forked tree when side shoots take over.

Regulated status and reporting

None of the three pages names a regulation, quarantine order or report line for the white pine weevil. For the agencies that take reports of regulated pests, see the guides on reporting a pest in Canada and the United States.

Management as the sources list it

NRCan lists shelterwood and small harvest blocks that keep partial shade, clipping and destroying infested leaders, selecting less susceptible trees, and a predatory fly, Lonchaea corticis, as a common natural enemy, and it says pesticide treatment is hard because adults are active early on warm open sites and larvae sit under the bark. Penn State describes pruning and burning infested leaders and an insecticide application aimed at feeding adults, and says birds, predators and parasitoids feed on the weevil but not enough to prevent damage. Kentucky lists spraying seedlings and new growth to kill feeding adults. This page gives no product names, rates or timings. For who may apply pesticides, see pesticide licences. A related species page covers the blue spruce, which NRCan and Penn State list as a host.