''Dendroctonus rufipennis'', the spruce beetle, is a species of

bark beetle A bark beetle is the common name for the subfamily of beetles Scolytinae. Previously, this was considered a distinct family (Scolytidae), but is now understood to be a specialized clade of the "true weevil" family (Curculionidae). Although th ...

native to

British Columbia British Columbia is the westernmost Provinces and territories of Canada, province of Canada. Situated in the Pacific Northwest between the Pacific Ocean and the Rocky Mountains, the province has a diverse geography, with rugged landscapes that ...

Newfoundland and Labrador Newfoundland and Labrador is the easternmost province of Canada, in the country's Atlantic region. The province comprises the island of Newfoundland and the continental region of Labrador, having a total size of . As of 2025 the populatio ...

Nova Scotia Nova Scotia is a Provinces and territories of Canada, province of Canada, located on its east coast. It is one of the three Maritime Canada, Maritime provinces and Population of Canada by province and territory, most populous province in Atlan ...

Ontario Ontario is the southernmost Provinces and territories of Canada, province of Canada. Located in Central Canada, Ontario is the Population of Canada by province and territory, country's most populous province. As of the 2021 Canadian census, it ...

Quebec Quebec is Canada's List of Canadian provinces and territories by area, largest province by area. Located in Central Canada, the province shares borders with the provinces of Ontario to the west, Newfoundland and Labrador to the northeast, ...

, Northern

Manitoba Manitoba is a Provinces and territories of Canada, province of Canada at the Centre of Canada, longitudinal centre of the country. It is Canada's Population of Canada by province and territory, fifth-most populous province, with a population ...

, the

Yukon Yukon () is a Provinces and territories of Canada, territory of Canada, bordering British Columbia to the south, the Northwest Territories to the east, the Beaufort Sea to the north, and the U.S. state of Alaska to the west. It is Canada’s we ...

, Alaska, Colorado, Wyoming, Montana, and

Maine Maine ( ) is a U.S. state, state in the New England region of the United States, and the northeasternmost state in the Contiguous United States. It borders New Hampshire to the west, the Gulf of Maine to the southeast, and the Provinces and ...

. They are known to destroy forests of

spruce A spruce is a tree of the genus ''Picea'' ( ), a genus of about 40 species of coniferous evergreen trees in the family Pinaceae, found in the northern temperate and boreal ecosystem, boreal (taiga) regions of the Northern hemisphere. ''Picea'' ...

trees including Engelmann,

White White is the lightest color and is achromatic (having no chroma). It is the color of objects such as snow, chalk, and milk, and is the opposite of black. White objects fully (or almost fully) reflect and scatter all the visible wa ...

, Sitka, and Colorado blue spruce. Adults average 4 to 7 mm in length.

Life cycle

The spruce beetle ''Dendroctonus rufipennis'', about 6 mm long, is one of the larger bark beetles found in

.Rose, A.H.; Lindquist, O.H. 1985. Insects of eastern spruces, fir and, hemlock, revised edition. Gov’t Can., Can. For. Serv., Ottawa, For. Tech. Rep. 23. 159 p. (cited in Coates et al. 1994, cited orig ed 1977) White spruce and

Engelmann spruce ''Picea engelmannii'', with the common names Engelmann spruce, white spruce, mountain spruce, and silver spruce, is a species of spruce native to western North America. It is highly prized for producing distinctive tone wood for acoustic guitars ...

are the principal hosts.Wygant, N.D.; Lejeune, R.R. 1967. Engelmann spruce beetle ''Dendroctonus obesus'' (Mann.) (= ''D. engelmanni'' Hopk.). p. 93–95 ''in'' Davidson, A.G.; Prentice, R.M. (Compilers and Eds.). Important forest insects and diseases of mutual concern to Canada, the United States, and Mexico. Can. Dep. For. Rural Devel., Ottawa ON, Pub. 1180. The beetles are attracted strongly to blowdowns, cull logs, and freshly-cut logs. Outbreaks of the spruce beetle, a transcontinental North American species, have been devastating to white and Engelmann spruces throughout western North America, from Arizona to Alaska, while smaller outbreaks have occurred in Alberta and Saskatchewan.Ives, W.G.H.; Wong, H.R. 1988. Tree and shrub insects of the prairie provinces. Gov’t Can., Can. For. Serv., Edmonton AB, Inf. Rep. NOR-X-292. 327 p.

oates et al. 1994 Oates may refer to: __NOTOC__ People * Oates (surname) * Kate Micucci, half of the musical comedy duo Garfunkel and Oates Places * Oates, Missouri, an unincorporated community in the United States * Mount Oates, on the border between Alberta and Br ...

/ref> The spruce beetle is the most serious pest of mature and overmature Alberta spruce in British Columbia;Cottrell, C.B. 1978. Spruce beetle in British Columbia. Environ. Can., Can. For. Serv., Victoria BC, For. Pest Leafl. 13. 4 p. small-diameter, rapidly growing trees were least susceptible to attack or death from spruce beetle, and the greater susceptibility of large-diameter, slowly-growing trees was more closely related to recent radial growth than to diameter.Hard, J.S.; Werner, R.A.; Holsten, E.H. 1983. Susceptibility of white spruce to attack by spruce beetles during the early years of an outbreak in Alaska. Can. J. For. Res. 13(4):678–684. (Cited in Coates et al. 1994). Measures that maintain radial growth rates offer the most likely defence.Hard, J.S. 1985. Spruce beetles attack slowly growing spruce. For. Sci. 31(4):839–850. (Cited in Coates et al. 1994).Hard, J.S.; Holsten, E.H. 1985. Managing white and Lutz spruce stands in south-central Alaska for increased resistance to spruce beetle. USDA, For. Serv., Pacific NW For. Range Exp. Sta., Portland OR, Gen. Tech. Rep. PNW-188. 21 p.Safranyik, L. 1985. Infestation incidence and mortality in white spruce stands by ''Dendroctonus rufipennis'' Kirby (Coleoptera: Scolytidae) in central British Columbia. J. Appl. Ent. 99(1):86–93. (Cited in Coates et al. 1994). The initial attack in the lower trunk is indicated by the red boring dust in the bark crevices and by pitch tubes, especially when weakened or recently dead trees are attacked. Overwintering adults construct egg tunnels for brood 1 in June, and a second set of tunnels in late July for brood 2. Some members of brood 1 emerge as adults in late July and construct additional tunnels, while others overwinter as mature

larva A larva (; : larvae ) is a distinct juvenile form many animals undergo before metamorphosis into their next life stage. Animals with indirect development such as insects, some arachnids, amphibians, or cnidarians typically have a larval phase ...

e and emerge as adults in July, along with another segment of the population that has overwintered as early larvae. A smaller bark beetle often found in spruce is the foureyed spruce bark beetle '' Polygraphus rufipennis''. The insect has a 1-, 2-, or 3-year life cycle, with 2-year being the most common, in which the flight and attack period starts in June or soon after most of the snow around the trees has melted. About 6 galleries per 929 cm², each about 12.5 cm long and parallel with the grain of the wood, are made in the inner bark, and 3 to 4 groups of eggs are laid along the sides of the galleries, about 100 eggs per gallery. Eggs hatch in 3 to 4 weeks. Larvae vary in size from about one-quarter to fully grown by the onset of the dormant season. They resume development the following June, pupate during the summer, and transform to the adult stage in later summer or early fall. The adults generally emerge from the trees, fall or crawl to the ground, and re-enter the same tree to hibernate, often clumping together under the bark. They emerge the following spring and fly to green trees, blowdowns, cull logs, or stumps to start another generation. The beetle may have a 1-year cycle at lower elevations, on warmer sites, or during an abnormally warm year, reaching the adult stage before the onset of winter. The 3-year cycle occurs at high elevations, on cold sites, or during unseasonably cold years.

Fungi A fungus (: fungi , , , or ; or funguses) is any member of the group of eukaryotic organisms that includes microorganisms such as yeasts and mold (fungus), molds, as well as the more familiar mushrooms. These organisms are classified as one ...

such as '' Leptographium abietinum'' may help beetles to overcome the defences of weakened trees during mass attack.Ohsawa, M.; Langor, D.; Hiratsuka, Y.; and Yamaoka, Y. 2000. Fungi associated with ''Dendroctonus rufipennis'' and ''Polygraphus rufipennis'' and white spruce inoculation tests. Can. J. Plant Pathol. 22:254–257. Fungi was isolated from ''Dendroctonus rufipennis'' and ''Polygraphus rufipennis'' and from discoloured wood around their galleries in white spruce in Canada. ''Leptographium abietinum'' was the most commonly isolated blue stain fungus for both beetle species. Inoculation of 5 species of fungi commonly isolated from both beetles on white spruce seedlings resulted in 71% of the seedlings colonized by ''L. abietinum'' being killed quickly, but with no mortality of seedlings inoculated with other fungi.

Population increase

The spruce beetle is one of many beetle species that have recently increased their breeding times due to

global warming Present-day climate change includes both global warming—the ongoing increase in global average temperature—and its wider effects on Earth's climate system. Climate change in a broader sense also includes previous long-term changes ...

. Their spread has also been aided by loggers leaving stumps that the beetles can overwinter within. Spruce beetle population has been correlated with drought conditions, this provides important information, as when periods of drought are predicted, population can be expected to increase. This overall pattern of climate is more predictive, and less variable than simply tempurature. The overpopulation of beetles in some forests in Kenai,

Alaska Alaska ( ) is a non-contiguous U.S. state on the northwest extremity of North America. Part of the Western United States region, it is one of the two non-contiguous U.S. states, alongside Hawaii. Alaska is also considered to be the north ...

, has damaged several spruce species that are no longer able to dwell there. The spruce beetle destroyed (2 billion board feet) of spruce forests in Alaska from 1992 to 1999 (about 30 million trees per year at the peak), and of

Utah Utah is a landlocked state in the Mountain states, Mountain West subregion of the Western United States. It is one of the Four Corners states, sharing a border with Arizona, Colorado, and New Mexico. It also borders Wyoming to the northea ...

forests in the 1990s (more than 3 million trees). Outbreaks from 1975 to 2000 were seen in

Montana Montana ( ) is a landlocked U.S. state, state in the Mountain states, Mountain West subregion of the Western United States. It is bordered by Idaho to the west, North Dakota to the east, South Dakota to the southeast, Wyoming to the south, an ...

(loss of 25 million board feet),

Idaho Idaho ( ) is a landlocked U.S. state, state in the Pacific Northwest and Mountain states, Mountain West subregions of the Western United States. It borders Montana and Wyoming to the east, Nevada and Utah to the south, and Washington (state), ...

(loss of 31 million board feet),

Arizona Arizona is a U.S. state, state in the Southwestern United States, Southwestern region of the United States, sharing the Four Corners region of the western United States with Colorado, New Mexico, and Utah. It also borders Nevada to the nort ...

(loss of over 100 million board feet), and British Columbia (loss of 3 billion board feet). As of 2000, the beetle was responsible for the loss of about 400 million board feet annually. ''Dendroctonus rufipennis'' is also a part of the ecosystem in

Colorado Colorado is a U.S. state, state in the Western United States. It is one of the Mountain states, sharing the Four Corners region with Arizona, New Mexico, and Utah. It is also bordered by Wyoming to the north, Nebraska to the northeast, Kansas ...

References

{{Taxonbar, from=Q6938319 Woodboring beetles Scolytinae Beetles of North America Insect pests of temperate forests

Life cycle

Population increase

See also

References