Dendroctonus rufipennis (spruce beetle)
- Taxonomic Tree
- Notes on Taxonomy and Nomenclature
- Distribution Table
- Risk of Introduction
- Hosts/Species Affected
- Host Plants and Other Plants Affected
- Growth Stages
- List of Symptoms/Signs
- Biology and Ecology
- Natural enemies
- Notes on Natural Enemies
- Plant Trade
- Wood Packaging
- Environmental Impact
- Threatened Species
- Detection and Inspection
- Similarities to Other Species/Conditions
- Prevention and Control
- Distribution Maps
Don't need the entire report?
Generate a print friendly version containing only the sections you need.Generate report
PicturesTop of page
IdentityTop of page
Preferred Scientific Name
- Dendroctonus rufipennis (Kirby, 1837)
Preferred Common Name
- spruce beetle
Other Scientific Names
- Dendroctonus borealis Hopkins, 1909
- Dendroctonus engelmanni Hopkins, 1909
- Dendroctonus obesus (Mannerheim, 1843)
- Dendroctonus piceaperda Hopkins, 1901
- Dendroctonus similis LeConte, 1857
- Hylurgus obesus Mannerheim, 1843
- Hylurgus rufipennis Kirby, 1837
International Common Names
- English: Alaska spruce beetle; beetle, Alaska spruce; beetle, eastern spruce; beetle, Engelmann spruce; beetle, red-winged pine; beetle, sitka-spruce; beetle, spruce; eastern spruce beetle; Engelmann spruce beetle; spruce bark beetle
- French: dendroctone d' Engelmann; dendroctone de l'épinette; dendroctone de l'epinette sitka
Local Common Names
- Germany: Riesenbastkaefer, Sitkafichten-; Sitkafichten Riesenbastkäfer
- DENCRU (Dendroctonus rufipennis)
Taxonomic TreeTop of page
- Domain: Eukaryota
- Kingdom: Metazoa
- Phylum: Arthropoda
- Subphylum: Uniramia
- Class: Insecta
- Order: Coleoptera
- Family: Scolytidae
- Genus: Dendroctonus
- Species: Dendroctonus rufipennis
Notes on Taxonomy and NomenclatureTop of page
DescriptionTop of page
Eggs of beetles of the family Scolytidae are smooth, ovoid, white and translucent. Spruce beetle eggs (1-2 mm long) are deposited in short rows along both sides of the egg gallery at a rate of between 4 and 14 eggs per centimetre of gallery (Holsten et al., 1989).
The larval stages of insects of the family Scolytidae are all similar in appearance and difficult to separate. They are white, 'c'-shaped, legless grubs. The head capsule is lightly sclerotized, amber in colour with dark, well-developed mouthparts. The abdominal segments each have two or three tergal folds and the pleuron is not longitudinally divided. The larvae do not change as they grow. Spruce beetle beetle larvae pass through four larval instars and are 4-6 mm long when mature (Holsten et al., 1989).
Scolytid pupae are white and mummy-like. They are exarate, with legs and wings free from the body. Some species have paired abdominal urogomphi. The elytra are either rugose or smooth, sometimes with prominent head and thoracic tubercles.
Adults are blackish-brown to black with reddish-brown or black elytra. They are cylindrical and range in length from 3.4 to 5.0 mm (average 4.2 mm) long and about 3 mm wide. The elytra are 2.5 times the length of the pronontum (Wood, 1982; Holsten et al., 1989).
DistributionTop of page
D. rufipennis is found throughout the range of spruce in North America, from eastern Canada, south along the Appalachian Mountains, west across the boreal forests of Canada and Alaska and south along crests of the Rocky Mountains and Cascades to northern California, Arizona and New Mexico (see map in Holsten et al., 1989).
See also CABI/EPPO (1998, No. 61).
Distribution TableTop of page
The distribution in this summary table is based on all the information available. When several references are cited, they may give conflicting information on the status. Further details may be available for individual references in the Distribution Table Details section which can be selected by going to Generate Report.Last updated: 24 Jul 2020
|Continent/Country/Region||Distribution||Last Reported||Origin||First Reported||Invasive||Reference||Notes|
|South Africa||Absent, Invalid presence record(s)|
|-British Columbia||Present, Widespread||Native||Invasive|
|-New Brunswick||Present, Widespread||Native||Invasive|
|-Newfoundland and Labrador||Present, Widespread|
|-Northwest Territories||Present, Widespread||Native||Invasive|
|-Nova Scotia||Present, Widespread||Native||Invasive|
|-Prince Edward Island||Present|
|Mexico||Absent, Unconfirmed presence record(s)||A record for Mexico in CABI/EPPO (1997) is now considered erroneous.|
|United States||Present, Widespread|
|-New Hampshire||Present, Widespread|
|-New Mexico||Present, Widespread||Native||Invasive|
|-New York||Present, Widespread||Native||Invasive|
|-South Dakota||Present, Widespread|
Risk of IntroductionTop of page
Pathways for human-assisted dispersal include transport of unprocessed pine logs or lumber, crates, pallets and dunnage containing bark strips. It is conceivable that larvae, pupae and overwintering adults could survive an ocean voyage and be introduced into a new location. Should this new location have spruce forests, it could become established and cause severe damage. A related North American species of Dendroctonus, the red turpentine beetle (D. valens) has recently been introduced and established in China and has killed more than 6 million pines in recent years (Sun et al., 2003).
HabitatTop of page
Hosts/Species AffectedTop of page
Normally D. rufipennis does not attack Picea mariana (black spruce). However, in outbreak situations, black spruce trees as small as 2 inches in diameter at breast height have been successfully attacked (Holsten E, USDA Forest Service, Alaska, personal communication, 2004).
Host Plants and Other Plants AffectedTop of page
Growth StagesTop of page
SymptomsTop of page
On standing trees, the most conspicuous evidence of attack is the presence of reddish-brown sawdust in the bark crevices on the bole and around the base of infested trees. Less noticeable evidence of attack includes entrance holes without sawdust and sawdust-clogged entrance holes. Masses of resin may accumulate around the entrance holes. These symptoms are most visible in the summer following attack and become less noticeable later in the year.
Sawdust in bark crevices and on the ground directly below the stems is a sign of infestation on windthrown trees and residual trees from harvesting operations. Spruce beetles are most common on the lower surfaces of fallen trees.
During the first autumn and winter following attack, trees are typically debarked by woodpeckers in search of larvae.
The removal of the bark of infested trees should reveal egg and larval galleries and life stages of the spruce beetle (Holsten et al., 1989).
List of Symptoms/SignsTop of page
|Leaves / yellowed or dead|
|Stems / gummosis or resinosis|
|Stems / necrosis|
|Stems / visible frass|
|Whole plant / frass visible|
|Whole plant / plant dead; dieback|
Biology and EcologyTop of page
The genus Dendroctonus consists of 19 species worldwide. Most occur on conifers in North and Central America. Two species: Dendroctonus armandi, native to China, and D. micans are found in Palearctic conifer forests (Wood, 1982). Several species are important forest pests, capable of reaching epidemic levels and killing thousand of trees. The genus Dendroctonus contains some of the most destructive forest insects in North and Central America.
In the Rocky Mountains, a generation of spruce beetle typically requires 2 years to complete. However, they can complete a generation in 1 year on warm sites at low altitudes or may require 3 years in cool, shaded locations on north-facing slopes. Two-year cycle spruce beetles may emerge between May and October, depending on local temperature. They attack soon after emergence. Adults emerging from August to October may represent a re-emergence of parent adults or the movement of maturing brood adults to overwintering sites.
Females bore through the outer bark and, after attracting a male and mating, construct egg galleries in the cambium layer and inner bark. Egg galleries are slightly wider than the adults and are tightly packed with frass and boring dust except for the terminal portion of the gallery. Total gallery length is about 13 cm. Eggs are deposited in short rows along both sides of the egg gallery at the rate of between 4 and 14 eggs per centimetre of gallery.
Larvae bore outward from the egg gallery, and feed communally for the first two instars. The third and fourth instars feed in individual galleries. The larval stage is the predominant life stage during the first winter, although some parent adults and eggs may also be present. Two-year cycle spruce beetles pupate about 1 year after attack by the parent adults. Pupation generally lasts 10-15 days and takes place in cells at the end of the larval galleries.
The second winter is passed in the adult stage, either in pupal sites or at the base of infested trees. During the following summer, the brood adults emerge from their overwintering sites and attack new host material.
In Alaska, 2 years are required to complete a generation. In eastern North America and in the coastal areas of the Northwest, a 1-year cycle may be more common. Adults emerge and attack from June to August and the brood overwinters as larvae. They resume development the following spring and emerge as adults in June (Holsten et al., 1989).
Natural enemiesTop of page
|Natural enemy||Type||Life stages||Specificity||References||Biological control in||Biological control on|
Notes on Natural EnemiesTop of page
For further information on the natural enemies of D. rufipennis, see Bellows et al. (1998) and Schmid and Frye (1977).
Plant TradeTop of page
|Plant parts liable to carry the pest in trade/transport||Pest stages||Borne internally||Borne externally||Visibility of pest or symptoms|
|Stems (above ground)/Shoots/Trunks/Branches||adults; eggs; larvae; nymphs; pupae||Yes||Pest or symptoms usually visible to the naked eye|
Wood PackagingTop of page
|Wood Packaging liable to carry the pest in trade/transport||Timber type||Used as packing|
|Solid wood packing material with bark||Spruce - crating, pallets, dunnage||Yes|
ImpactTop of page
North American spruce forests have a long history of spruce beetle outbreaks. According to early records, spruce beetle was first recognized as a pest of spruce in the north-eastern USA in the early 1800s, when several outbreaks killed large numbers of trees (Hopkins, 1901). These outbreaks continued until the beginning of the twentieth century but have since dwindled to smaller outbreaks covering several thousand acres, presumably due to a reduction in the area of mature spruce forests (Weiss et al., 1985). This insect has also been a serious pest in the Rocky Mountains and in portions of Oregon and Washington (Furniss and Carolin, 1977). Historical records summarized by Schmid and Frye (1977) report on outbreaks in western Colorado in the mid 1870s. During this same period an outbreak killed more than 90% of the spruce on more than 5300 ha in southern New Mexico. Another massive outbreak occurred in western Colorado between 1942 and 1948 following a severe storm resulting in extensive windthrow. Spruce beetle has been a continuing problem in portions of Alaska since the early 1970s. This outbreak began to increase significantly in 1992 and peaked in 1996 when nearly 460,000 ha were infested (Ciesla and Coulston, 2002).
Environmental ImpactTop of page
Threatened SpeciesTop of page
|Threatened Species||Conservation Status||Where Threatened||Mechanism||References||Notes|
|Rangifer tarandus (reindeer)||No Details||;||Ecosystem change / habitat alteration||US Fish and Wildlife Service (1994)|
|Tamiasciurus hudsonicus grahamensis (Mount Graham red squirrel)||USA ESA listing as endangered species||Arizona||Ecosystem change / habitat alteration||US Fish and Wildlife Service (2007)|
Detection and InspectionTop of page
Similarities to Other Species/ConditionsTop of page
In Alaska, Canada and the north-eastern USA, the Allegheny spruce beetle (Dendroctonus punctatus) also attacks spruce. This insect may be distinguished from spruce beetle by its uniformly brown colour (Holsten et al., 1989). D. rufipennis also resembles to some extent the Douglas-fir beetle (D. pseudotsugae). However, D. pseudotsugae is found on Pseudotsuga menziesii (Furniss and Carolin, 1977).
To ensure positive identification, bark beetles believed to be a new introduction, should be examined by a taxonomist with expertise in the family Scolytidae.
Prevention and ControlTop of page
Due to the variable regulations around (de)registration of pesticides, your national list of registered pesticides or relevant authority should be consulted to determine which products are legally allowed for use in your country when considering chemical control. Pesticides should always be used in a lawful manner, consistent with the product's label.Cultural Control
A number of cultural tactics, designed to modify forest conditions, are available to manage spruce beetle infestations. Infested and susceptible spruce can be removed from the overstorey to encourage regeneration of a new, healthy, vigorous forest. Partial cuts can be used to remove infested and susceptible trees to improve the growth of the residual stand. Trap trees, green trees of large diameter (>46 cm), can be felled before adult flight to attract flying beetles. Trap trees must be removed from forests before the brood completes development and emerges (Holsten et al., 1989).
No biological control programme has been developed for spruce beetle. Unless large volumes of favourable host material exist, this insect is kept at low levels by a combination of factors including a complex of natural enemies (Bellows et al., 1998).
Several tactics involving chemicals have been used. The application of chemicals to the boles of infested trees to kill broods and emerging adults has been used. However, as is the case with other bark beetles, this procedure is expensive and of marginal effectiveness as long as forest conditions are favourable for the development of spruce beetle outbreaks. The boles of high value, uninfested trees in recreation sites or homesites can be sprayed with a residual insecticide to prevent attack. This treatment can protect trees for up to 2 years (Holsten et al., 1989).
Aggregating pheromones can increase the effectiveness of trap trees. The anti-attractant pheromone methylcyclohexenone shows promise as a repellent but is not yet an operational pest management tactic (Holsten et al., 1989).
Infested logging debris or windthrow can be exposed to direct sunlight to kill spruce beetle broods. Infested material is cut into 1.5-2 m lengths and rotated at 2-week intervals to expose the bark surface to the sun. This technique is effective in the Rocky Mountains but not in Alaska (Holsten et al., 1989).
Infested material can be piled and burned to destroy broods. Only the bark has to be burned (Holsten et al., 1989).
Monitoring of spruce beetle consists of aerial and ground surveys designed to locate groups of dead and dying trees and confirm the presence of infestations. In areas where this insect has a history of causing damage, these surveys are conducted on an annual basis. Attractant pheromones can also be used to monitor the relative abundance of adult beetles.
Integrated Pest Management
Integrated pest management of spruce beetle consists of monitoring of forests for the presence of infestations and management to keep forests in a healthy growing condition. Guidelines are available to rate the hazard of spruce forests for susceptibility to spruce beetle attack (Alexander, 1986). The removal of infested and high-risk trees, treatment of logging debris and windthrow, and the judicious use of trap trees are effective pest management tactics. Attacks in high value trees can be prevented by the application of insecticides. Many forests with a heavy spruce component and susceptible to outbreaks of spruce beetle occur at high altitudes (e.g. the Rocky Mountains) or remote, inaccessible areas (e.g. Alaska) where it is logistically difficult to implement pest management programmes. Therefore, this insect remains a major threat to North American spruce forests.
ReferencesTop of page
Alexander RR, 1986. Silvicultural systems and cutting methods for old-growth spruce-fir forests in the central and southern Rocky Mountains. USDA Forest Service, Rocky Mountain Forest and Range Experiment Station, General Technical Report RM-GTR-126.
Cibrián Tovar D, Méndez Montiel JT, Campos Bolaños R, Yates III HO, Flores Lara JE, 1995. Forest Insects of Mexico. Chapingo, México: Universidad Autonoma Chapingo. Subsecretaria Forestal y de Fauna Silvestre de la Secretaria de Agricultura y Recursos Hidraulicos, México. United States Department of Agriculture, Forest Service, USA. Natural Resources Canada, Canada. North American Forestry Commission, FAO, Publication 6.
Ciesla WM, Coulston J, 2002. Report of the United States on the criteria and indicators for sustainable management of temperate and boreal forests of the United States, Criterion 3 - Maintenance of ecosystem health and vitality, Indicator 15, Area and percent of forest affected by processes or agents beyond the range of historic variation. USDA Forest Service, On line: http://www.fs.fed.us/research/sustain/.
EPPO, 2014. PQR database. Paris, France: European and Mediterranean Plant Protection Organization. http://www.eppo.int/DATABASES/pqr/pqr.htm
Furniss RL, Carolin VM, 1977. Western Forest Insects. Washington DC, USA: US Department of Agriculture Forest Service, Miscellaneous Publication No. 1339.
Holsten EH, Thier RW, Schmid JM, 1989. The spruce beetle. USDA Forest Service, Forest Insect and Disease Leaflet 127.
Hopkins AD, 1901. Insect enemies of the spruce in the Northeast. USDA Bureau of Entomology, Washington D.C., Bulletin 28, 80 pp.
Schmid JM, Frye RH, 1977. Spruce beetle in the Rockies. USDA Forest Service, Rocky Mountain Forest and Range Experiment Station, Fort Collins, Colorado, USA. General Technical Report RM-49.
Sun J, Gillette NE, Miao Z, Kang L, Zhang Z, Owen DR, Stein JD, 2003. Verbenone interrupts attraction to host volatiles and reduces attack on Pinus tabuliformis (Pinaceae) by Dendroctonus valens (Coleoptera: Scolytidae) in the People's Republic of China. Canadian Entomologist, 135(5):721-732.
Weiss MJ, McCreery LR, Millers I, Miller-Weeks M, O'Brien JT, 1985. Cooperative survey of red spruce and balsam fir decline and mortality in New York, Vermont and New Hampshire, 1984. USDA Forest Service, Northeastern Area, Broomall, PA, USA, Report NA-TP-11.
Wood SL, 1963. A revision of the bark beetle genus Dendroctonus Erichson (Coleoptera: Scolytidae). The Great Basin Naturalist, 23:1-117.
CABI, Undated. CABI Compendium: Status as determined by CABI editor. Wallingford, UK: CABI
Ciesla WM, Coulston J, 2002. Report of the United States on the criteria and indicators for sustainable management of temperate and boreal forests of the United States, Criterion 3 - Maintenance of ecosystem health and vitality, Indicator 15, Area and percent of forest affected by pr., USDA Forest Service. http://www.fs.fed.us/research/sustain/
Schmid JM, Frye RH, 1977. Spruce beetle in the Rockies. In: USDA Forest Service, Rocky Mountain Forest and Range Experiment Station, Fort Collins, Colorado, USA. General Technical Report RM-49,
Weiss MJ, McCreery LR, Millers I, Miller-Weeks M, O'Brien JT, 1985. Cooperative survey of red spruce and balsam fir decline and mortality in New York, Vermont and New Hampshire, 1984., Broomall, PA, USA: USDA Forest Service, Northeastern Area.
Distribution MapsTop of page
Select a dataset
CABI Summary Records
Unsupported Web Browser:
One or more of the features that are needed to show you the maps functionality are not available in the web browser that you are using.
Please consider upgrading your browser to the latest version or installing a new browser.
More information about modern web browsers can be found at http://browsehappy.com/