Montana Field Guide

The Banded Elm Bark Beetle (Scolytus schevyrewi) is a nondescript bark beetle. Adults are around 2.7-4.3 mm in length with a reddish to dark brown coloring and typically has a dark/black band across the elytra (LaBonte 2010). Larvae are 4.8 -7.5 mm in length with a white body, cream colored head and brown mouthparts. As with other bark beetles, larvae feed on the cambium of trees forming galleries within the bark of host trees.

This exotic bark beetle is native to Russia, China, and other central Asian countries. Its primary hosts are deciduous trees such as Siberian elm and Russian Olive. In addition to mechanical damage caused by larvae leading to the death of host trees, this species can also serve as a vector for Dutch elm disease. The species was first found in north America in Colorado in 2003, although it had been collected as early as 1998 in New Mexico. As of 2011 has been found in 28 states including Montana, and four Canadian provinces

The phenology of this species has not been described in Montana. In Colorado flights were initiated in April and ceased in October (Lee et al. 2011). In Manitoba and Saskatchewan, the adult flight period was May through October (Veillleux 2012). As emergence is corelated with temperature (Veillleux 2012), emergence dates in Montana are likely more similar to those observed in Saskatchewan.

Overwintering pupa emerge as adults in the spring or early summer. Females find a suitable host tree, and dig a gallery in the phloem. Males search for these burrow entrances to find females and mate. After fertilization females deposit 20 – 120 eggs in separate chambers within the gallery (Wang 1992). Upon hatching, larvae burrow through the phloem, and eventually migrate to the outer bark and construct pupal chambers. This species is thought to have five larval instars (Wang 1992, Fan et al. 2011). Upon emergence adult beetles feed on bark in the crotches of twigs of healthy trees (Witchosky 2004 ). Generation within the species native range is 40-45 days (Wang 1992). At northern latitudes, a second generation may be produced in the summer (Veillleux 2012), so in total 2-3 generations per year.

This species can be definitively identified by the characteristic band across the elytra from which its common name is derived and when present the shape and position of the spine on the sternum. For an in-depth discussion of these characteristics see LaBonte 2010.

Deciduous forests. This species appears to favor dry climates but can be found anywhere its host species exist (see food comments section below for specific species).

As its common name suggests the Banded Elm Bark Beetle is most commonly associated with Ulmus species (elms). However, in its native range host trees also include species in the following genera: Caragana, Elaeagnus, Malus, Prunus, Pyrus, and Salix (as reviewed in Veillleux 2012). In North America the species has been found in association with the American Elm (U. Americana), English Elm (U. procera), Siberian Elm (U. pumila), and Rock Elm (U. thomasii) (Negrón et al. 2005). Of these species, only the American Elm is native to Montana although other species used in landscaping or otherwise introduced may be impacted.

The Banded Elm Bark Beetle does not disperse far from infected host trees, so long-distance movement can be reduced through restrictions on transport of wood and wood products from host trees.

For information and resources on plant pests and diseases see the USDA's Animal and Plant Health Inspection Service's Plant Pests and Diseases Profiles