European elm bark beetle: what the agencies record

This page describes what the named sources say. It is not a diagnosis of any tree and does not say what should be done with one. The European elm bark beetle (Scolytus multistriatus) is an introduced insect in North America, and none of the three pages read lists the beetle itself as regulated or notifiable. Each section names its source, all read on October 8, 2026. The disease the beetle carries has its own page, Dutch elm disease. The parent page, insect pests of trees, compares this beetle with the other pests on the list.

Names

Natural Resources Canada, called NRCan, gives the scientific name Scolytus multistriatus (Marsham), the French name scolyte europeen de l'orme and the other common names smaller European elm bark beetle and lesser European elm bark beetle. It places the beetle in the family Curculionidae. Utah State University Extension uses the abbreviation SM for the same species in its Elm Bark Beetles page, which sets it beside the banded elm bark beetle, Scolytus schevyrewi. The Morton Arboretum names it as one of two insects that transmit Dutch elm disease, the other being the native elm bark beetle, Hylurgopinus rufipes.

Hosts

NRCan says the main host in Canada and the United States is white or American elm, and that all native and introduced elm species in North America are attacked, including rock elm, slippery elm, Siberian elm, Chinese elm and the closely related Japanese zelkova. It adds that the beetle is noted on other broadleaved trees in other places, and that none of those are susceptible to Dutch elm disease. Utah State lists elm as the host and hackberry as possible. The Morton Arboretum says all native elms and European elms are susceptible to the disease, while lacebark and Siberian elms, which it calls Asiatic elms, are highly resistant to it.

What the sources say to look for

NRCan describes adults 2.2 to 3.9 millimetres long with a black thorax and reddish-brown wing covers. Utah State gives a size of 1/13 to 1/9 inch, reddish brown, with a thumbnail-like rear end and a central spine, and describes the larvae as legless white grubs with a brown head. NRCan lists red sawdust on the bark around holes on the lower trunk and larger branches of dying trees as evidence of colonization. Under the bark, it says, the egg gallery is a single branch running across the grain of the wood, horizontal or V-shaped, 2.5 to 5.5 centimetres long, and the larval tunnels radiate from it in a fan shape. It contrasts these with the native elm bark beetle, whose larval tunnels run parallel to the grain at right angles to the egg gallery. NRCan also says round exit holes from emerging adults may be clustered in a shot-hole pattern.

Life cycle as the sources state it

NRCan says there are two generations a year in Canada and three farther south in the United States, and that the beetle overwinters as larvae, pupae or sometimes adults under the bark. Utah State gives two to three generations a year, overwintering larvae and adult emergence from April to mid-May and through summer. The Morton Arboretum gives two generations a year in the Midwest. NRCan describes two feeding habits. Adults feed in the crotches of small twigs on healthy elms, which it calls the common site of infection. They bore into moribund or recently dead trees to lay eggs, finding them through chemicals the dying trees give off and then drawing other beetles with an aggregation pheromone. It says healthy trees are used for feeding and are rarely colonized for breeding.

The link to Dutch elm disease

NRCan says the beetle does little direct harm to healthy trees, and that its greatest threat is as a prominent vector of the fungi Ophiostoma ulmi and O. novo-ulmi, which cause Dutch elm disease. Spores stick to adults emerging from infected trees and enter healthy trees through the feeding scars in twigs. NRCan stresses that it is the pathogen, not the beetle, that kills the tree. It reports that the beetle is one of three bark beetles known to carry either fungus in North America, that it has displaced the native elm bark beetle as the main vector in the southern parts of their shared range, and that it shares much of its range with the banded elm bark beetle. Utah State says that without disease transmission neither species typically kills trees, and that larval feeding can girdle branches or trees. The Morton Arboretum says the beetles lay eggs in infected trees and carry spores to healthy trees when they emerge to feed on twigs and upper branches.

Where it is reported

NRCan says the beetle is native throughout Europe, including western Russia and Turkey. It reached North America on elm logs carrying live larvae, was first found in Massachusetts in 1909 and in Ontario in 1946, and is present from Nova Scotia to British Columbia and in most of the contiguous United States. It lists the beetle as also introduced to Lebanon, Iran, Egypt, Algeria, Australia, New Zealand and possibly temperate South America. NRCan adds that Canadian records west of the native range of white elm, many from British Columbia, come from survey traps and have no host record. Utah State describes the beetles as very common but rarely damaging to Utah's common Siberian elms.

Regulated status and reporting

None of the three pages names an order or a report line for the beetle. NRCan notes that pheromones and pesticides are regulated products in Canada and that registered products can be checked in the Health Canada database. For the agencies that take reports of regulated pests, see the guides on reporting a pest in Canada and the United States.

Moving wood

NRCan says that restrictions on moving firewood, or any wood with bark, out of infected areas matter because that is a common way beetles and the pathogen are carried. The Morton Arboretum says transporting diseased elm firewood may spread the disease to areas without it. Wider rules are on the moving wood and firewood page.

Management as the sources list it

NRCan says many trials of chemical control aimed at the beetles, and introductions of nematodes and parasitoids, were made, that the results are hard to assess, and that the general conclusion is that reducing beetle numbers has made little impact on the spread of the disease. It lists monitoring susceptible stands, keeping trees vigorous, removing dead, damaged and infected trees, preventing movement of infected wood, and pheromone traps for monitoring and in some cases suppression, and calls active sanitation probably the most effective practice. Utah State lists reducing tree stress and removing dead or dying elm wood from the site. The Morton Arboretum names sanitation as a key preventive measure, since the beetles breed in dead or dying elms and in elm wood with the bark on. This page gives no product names, rates or timings. For who may apply pesticides, see pesticide licences.