Forest Insect

& Disease

Leaflet 11

Revised June 2009

U.S. Department of Agriculture • Forest Service

Jeffrey Pine Beetle

Sheri L. Smith1,Robert R. Borys 2 and Patrick J. Shea 3

Jeffrey pine beetle (Dendroctonus jeffreyi 

Hopkins) is the primary insect pest of 

Jeffrey pine (Pinus jeffreyi Grev. and Balf.). 

The beetle is native to North America, 

with a range that follows Jeffrey pine, its 

only host, in California, Nevada, Oregon 

and Baja Norte California, 

Mexico. As with other aggressive, 

tree-killing bark beetles, D. 

jeffreyi experiences boom or bust 

population fluctuations that cause 

dramatic and extensive mortality 

of Jeffrey pines following severe 

or prolonged drought. During 

outbreaks, any tree greater than 4” 

diameter at breast height may be 

attacked and killed; tree mortality 

tends to occur in groups, with 

group sizes ranging from 10 to 50 

to several hundred trees. Larger 

diameter trees are often preferred 

with mortality occurring singly or 

in small groups (Figure 1). Larger 

“group kills” frequently occur in 

pole-size stands (Figure 2). Long 

term and widespread prevention 

is dependent on tree and forest 

resistance related to tree density. 

Management activities that 

reduce stand density help lower 

susceptibility to Jeffrey pine beetle. 

Records of Jeffrey pine mortality 

date back to the early 1920’s on the 

Figure 1. Large diameter Jeffrey pines killed by Jeffrey pine 

beetle, Luther Pass, Lake Tahoe Basin Management Unit, 

2007.

1 Regional Entomologist, USDA Forest Service, Forest Health Protection, Pacific Southwest Region, 

Susanville, CA.

2 Entomologist, retired, USDA Forest Service, Pacific Southwest Research Station, Placerville, CA.

3 Research Entomologist, retired, USDA Forest Service, Pacific Southwest Research Station, Davis, CA.

Inyo National Forest (Inyo County, CA), 

where beetle populations reached outbreak 

levels in windthrow and subsequently 

caused the death of more than 13 million 

board feet of standing timber across 

32,000 acres. 
2

Figure 2. Groups of Jeffrey pines killed by Jeffrey pine beetle, Lake Tahoe Basin Management Unit, 1995.

More recently, outbreaks of Jeffrey pine 

beetle have typically been associated with 

drought. During 1965-1966 outbreaks 

were recorded in Lassen, Modoc, Placer, 

and Plumas Counties, CA. High levels of 

Jeffrey pine mortality was also recorded 

between 1976-1981 throughout much 

of the range of Jeffrey pine in California 

and again between 1992 and 1994 on 

the east side of the Sierra Nevada range 

from Bishop, CA north to the southern 

end of the Cascade Range. This outbreak 

occurred near the end of a 6 year drought 

period. During a recent (2002-2004) 

severe drought in Southern California 

this beetle caused high levels of Jeffrey 

pine mortality. Many stands historically 

dominated by Jeffrey pine or a mixture 

of Jeffrey and ponderosa pines now are 

much denser and have a large component 

of white fir. During protracted or severe 

drought periods, the large diameter pines 

do not compete well with the smaller 

trees for water and nutrients and are thus 

attacked and killed by bark beetles. Jeffrey 

pine beetle will attack fire-injured trees; 

however, subsequent outbreaks within 

the fire perimeter or in surrounding uninjured trees are not common. 

Jeffrey pine beetle is native to North 

America, and is being distributed 

throughout most of the range of Jeffrey 

pine from the southern border of Oregon 

down through eastern California, west 

into Nevada and south to the Sierra San 

Pedro Mártir Mountains of Baja Norte 

California, Mexico (Figure 3). Although 

Jeffrey pine occurs in the San Jacinto, 

Santa Rosa and Laguna mountain ranges 

in Southern California, Jeffrey pine beetle 

has not been observed there.

Host

Jeffrey pine is the only known host of 

the beetle. This pine is the dominant 

yellow pine in forests east of the Sierra 

Nevada crest, in some parts of the 

Southern Cascades, southward into the 

Transverse and Peninsular ranges and 

into northern Baja California. Forests in 

the Sierra San Pedro Mártir, Baja Norte 

California, Mexico are the southern limit 

for this pine species and the Klamath 

Mountains in southwest Oregon are the 

northern limit. Jeffrey pine’s distribution 

is intimately linked with serpentine soils 

in the northwest portion of the range and 

strongly reflects climatic and elevational 

factors in the northeast, central, and 

southern portions. Jeffrey pine is cold 

hardy, drought tolerant and adapted to 
3

Figure 3. Distribution of Jeffrey pine and Jeffrey pine beetle in North 

America. 

short growing seasons. It competes well 

and typically dominates other conifers on 

cold and xeric sites, and those with poor 

soil conditions. Jeffrey pine’s innately 

short growing season, limited nutrient and 

water demands, and extensive root growth 

are adaptations to poor sites; however, 

they are slow growing, which makes the 

loss of large trees a long-term impact.

Evidence of Attack and 

Infestation

Jeffrey pine beetle-attacked trees are not 

usually detected until their crowns fade 

from green to yellow to reddish-brown. 

Foliage on trees attacked successfully 

during early summer may begin to fade 

during late fall of the same year. Trees 

attacked later in the summer typically do 

not fade until late spring or early summer 

of the following year. Trees killed by 

Jeffrey pine beetle usually 

fade evenly throughout the 

crown. Crown fading does 

not typically occur until 

Jeffrey pine beetle larvae are 

well developed; offspring 

beetles have likely already 

vacated a tree when the 

crown turns reddish-brown. 

Large, reddish pitch tubes 

(Figure 4) are readily 

observed on the bark 

surface of infested trees. 

Pitch tubes mark the points 

of attack and can be found 

long before crown fading. 

Attacks are made on the 

mid-bole with additional 

attacks extending high up 

on the bole and down to 

ground line. Successful 

attacks are indicated by 

pink to dark-reddish 

pitch tubes containing 

boring dust and frass, 

while unsuccessful attacks 

(“pitchouts”) are typically 

creamy white to yellow 

and may lack boring dust 

and frass. Confirmation of 

successful vs. unsuccessful 

attacks is gained by removing bark and 

looking for life stages or galleries. During 

droughty periods trees may lack sufficient 

resin to produce pitch tubes. In these 

cases boring dust in bark crevices and 

around the tree base may be the only 

visible indicators of successful attack.

Successful attacks can be confirmed by 

removing a section of bark and examining 

the gallery pattern in the phloem or 

inner bark. Galleries are constructed by 

adult beetles and serve as sites for egg 

deposition. Gallery patterns created by 

Dendroctonus bark beetles are typically 

species-specific and can be used to 

identify which beetles have attacked 

the tree. Jeffrey pine beetle galleries are 

predominantly straight, vertically oriented 

with the tree bole, packed with frass and 

usually have a characteristic “J” shape 

(Figure 5). The length of galleries varies 

greatly but typically they range from about 

10 to 40 inches. Larval mines are much 
4

smaller, extending across the grain at 

right angles from the parent gallery, and 

terminating in open, oval-shaped pupal 

cells. Circular emergence holes can be 

seen on the outer bark surface following 

adult emergence. Larger holes, caused by 

woodpeckers scaling and drilling for food, 

may also be observed on the tree bole 

(Figure 6). It is estimated that over 20,000 

beetles can emerge from a single, largediameter Jeffrey pine tree (Josep Riba, 

unpublished data). 

When diagnosing Jeffrey pine beetle as 

the cause of tree mortality, it is important 

to establish that the infested tree is a 

Jeffrey pine. Ponderosa pines look very 

similar to Jeffrey pines but are attacked by 

the mountain pine beetle (Dendroctonus 

ponderosae Hopkins), a closely related 

species that is similar in appearance and 

habit to Jeffrey pine beetle. Ponderosa 

and Jeffrey pines are often found growing 

in mixed stands and a closer look is 

often needed to differentiate between 

these trees. Jeffrey pines can often be 

distinguished from ponderosa pines by 

their aromatic bark that smells like vanilla. 

Other distinguishing characteristics are 

foliage color; Jeffrey pine needles are more 

blue-green compared to the yellow-green 

needles on ponderosa pines; the under 

surface of the bark scales on Jeffrey pines 

are red-brown compared to powderyyellow on ponderosa pines; and the cones 

(3-6” in length) on ponderosa pines have 

spines pointing outward which are prickly, 

whereas Jeffrey pine cones (5-9” in length) 

have recurved spines. Ponderosa pines are 

Figure 4. Jeffrey pine beetle pitch tube on outer 

surface of bark. 

Figure 5. Jeffrey pine beetle galleries are 

predominantly straight, vertically oriented and 

usually have a characteristic “J” shape.

Figure 6. Holes in the bark created by 

woodpeckers drilling to feed on Jeffrey pine 

beetles.
5

also attacked by the western pine beetle 

(Dendroctonus brevicomis LeConte) which 

has a sinuous gallery pattern. This beetle 

does not attack Jeffrey pine.

 

Life History

Jeffrey pine beetle is one of the largest 

species of bark beetles. Adults are stout, 

cylindrical beetles about five-sixteenths 

inch long and dark-brown to black 

(Figure 7). Beetles develop through 

four life stages: egg, larva, pupa and 

adult. Life stages can be observed in 

an infested tree by removing a section 

of bark and examining the inner bark. 

Upon emergence Jeffrey pine beetle adults 

fly to a new tree and attack it by boring 

through the outer bark into the phloem. 

The female beetle arrives first, forms an 

entrance tunnel, and is then joined by the 

male beetle. Although not completely 

understood, evidence strongly suggests 

that aggregating pheromones are released, 

attracting high numbers of additional 

female and male beetles to the same tree. 

The beetles usually attack at mid-bole; 

however, attacks on the upper and lower 

bole are also common. Pole size and 

larger trees are typically attacked, but trees 

as small as 4 inches in diameter can be 

attacked during outbreaks.

In newly attacked trees, beetles etch 

vertical galleries on the inner surface 

of the bark by boring diagonally across 

the wood grain for two or three inches, 

then vertically upward and parallel to the 

grain for an additional two to three feet. 

Each gallery is constructed by a single 

pair of beetles. As construction of the 

gallery progresses, the female deposits 

individual eggs in niches along the sides 

(Figure 8). The gallery is packed solidly 

with boring dust and frass. Eggs are oval, 

pearly-white (Figure 8), and hatch in one 

to three weeks. Larvae are curved, white, 

legless grubs with yellow (sclerotized) 

head capsules (Figure 9). Mature larvae, 

similar in size to adult beetles, tunnel in 

the phloem, away from the main gallery, 

across the wood grain. Pupae are white, 

slightly smaller than last instar larvae 

(Figure 10) and mature into adults in 

about 10 days. Mature larvae, pupae, and 

new adults are in cells at the ends of the 

larval galleries. Beetles emerge from the 

pupal cells by tunneling out through the 

bark.

Figure 7. Jeffrey pine beetle adults are stout, cylindrical beetles about five-sixteenths inch long and 

dark-brown to black.
6

One or two generations can be completed 

per year depending on location and 

temperature. One generation may be 

more common in northern California, 

whereas a second generation may occur 

in the same year in warmer areas like 

Southern California and Baja Norte 

California, Mexico. The occurrence 

of multiple generations can be easily 

confused with an extended emergence 

period. The principal period of attack is 

in June and July, but attacks can also occur 

through September into early October. 

The beetle overwinters primarily in the 

larval stage. 

Common Associates

Many organisms occur with the Jeffrey 

pine beetle. Adult beetles carry yeasts 

along with the mycangial blue-staining 

fungus, Ophiostoma clavigerum RobinsonJeffrey & Davidson (Six and Paine 1997) 

into trees. These organisms find a fertile 

medium for development in the inner bark 

and sapwood, and their growth decreases 

the flow of nutrients and water in the 

tree. This aids in tree death and causes 

the characteristic crown fading patterns. 

Bluestain fungi can discolor the sapwood 

to a bluish-color in one to several months, 

reducing value for wood products.

Associated insects, mostly minor species 

that invade after the tree is declining, 

are also found in trees attacked by the 

Jeffrey pine beetle. Common associates 

include the pine engraver (Ips pini Say.), 

the emarginate ips (I. emarginatus Lec.), 

the red turpentine beetle (D. valens Lec.) 

) and the California flatheaded borer 

(Melanophila californica Van Dyke). The 

pine engraver may precede the Jeffrey pine 

beetle or attack at about the same time. 

It mines in the top part of the tree bole, 

usually above the area infested by Jeffrey 

pine beetle. The emarginate ips generally 

attacks shortly after Jeffrey pine beetle 

and works in the lower part of the stem 

where its galleries are often intermingled 

with Jeffrey pine beetle galleries. Attacks 

by the red turpentine beetle may precede, 

be simultaneous with, or follow attacks 

by Jeffrey pine beetle. Attacks by red 

turpentine beetle are usually on the lower 

bole near the ground and can extend 

into the root system. The California 

flatheaded borer is often found after most 

bark beetles have emerged, but can also 

be found prior to attack by Jeffrey pine 

beetle in slow growing, drought-stressed 

or diseased trees. Trees attacked by Jeffrey 

Figure 8. Jeffrey pine beetle eggs.

Figure 9. Jeffrey pine beetle larvae.

Figure 10. Pupa in pupal cell on inner surface of 

bark.
7

pine beetle also commonly have some level 

of western dwarf mistletoe (Arceuthobium 

campylopodum Engelm.) infection.

The blackbellied clerid (Enoclerus 

lecontei Wolcott), the redbellied clerid (E. 

sphegeus F.), and the blue-green ostomid 

(Temnochila chlorodia Mannerheim) are 

important predators of Jeffrey pine beetle. 

In addition, woodpeckers feed heavily on 

most life stages (Figure 6). 

Long-term Prevention

Normally Jeffrey pine beetle populations 

are kept in check by natural enemies, 

climatic factors, and host resistance. 

During periods with adequate 

precipitation, Jeffrey pine beetle-caused 

tree mortality usually goes unnoticed, 

consisting of only a few trees across the 

landscape. During drought periods, 

however, Jeffrey pine beetles can cause 

high levels of tree mortality across 

extensive areas. Management activities 

that promote tree health and vigor will 

reduce tree susceptibility to successful 

attack. Reducing stand density and 

improving tree resistance hampers beetle 

success; thinning is the only treatment 

available to increase tree resiliency 

to drought and bark beetles over the 

long term. Maintaining an appropriate 

basal area and a diversity of species and 

age classes is the best defense against 

undesirable Jeffrey pine beetle-caused 

tree mortality, even during outbreaks. 

Thinning also reduces flammable fuels, 

thereby reducing fire threat to people and 

structures during years of high fire danger.

During thinning projects, consideration 

should be given to the use of a stump 

treatment to prevent annosus root disease 

caused by the fungus Heterobasidion 

annosum ([FR] Bref.). Annosus root 

disease is widespread throughout many 

areas of California and can cause mortality 

of infected trees. Windborne spores enter 

through stump surfaces. The fungus 

grows into the roots, causes decay, and 

eventually can kill the tree. The disease 

spreads from tree to tree through root 

contacts. The best way to avoid infection 

is prevention. Treatment of all freshly cut 

stumps with a registered borate compound 

prevents infection. Stumps should be 

treated within 4 hours after trees are cut.

Short-term Prevention

 Insecticides

Insecticides are available to prevent 

bark beetle attacks. Such treatments are 

typically reserved for high value trees, 

such as those located in campgrounds, 

administrative sites, or on private 

property. Smith (1982) assessed the 

residual toxicity of carbaryl (2% a.i.) on 

treated logs and found a 92% reduction in 

length of egg galleries of Jeffrey pine beetle 

compared to untreated logs. Additional 

trials are underway to determine efficacy 

and duration of insecticides registered 

for use against bark beetles. Based on 

circumstantial evidence from Jeffrey pines 

sprayed in campgrounds in California 

and Nevada, some of the same preventive 

insecticides effective against other western 

bark beetles may also be effective against 

Jeffrey pine beetle.

Preventive sprays should be applied 

to the tree bole to bark saturation and 

should reach as high up the bole as the 

equipment will allow (at least mid-bole 

or higher, 30-40 feet). Tree protection 

can be gained for 1-2 years depending 

on the insecticide. Insecticide use is 

governed by the provisions of the Federal 

Insecticide, Fungicide, and Rodenticide 

Act, as amended. This act is administered 

by the Environmental Protection Agency 

(EPA). Registrations of pesticides are 

under constant review by the EPA; consult 

your local forest entomologist, county 

agriculture agent, or State extension 

specialist to be sure the intended chemical 

and use are legal. It is always important to 

carefully follow all label instructions when 

using registered pesticides.

 Removing infested trees

Removing infested trees can reduce the 

number of trees infested in the immediate 

surrounding area the following year. 
The U.S. Department of Agriculture (USDA) prohibits discrimination in all its programs and activities on the 

basis of race, color, national origin, age, disability, and where applicable, sex, marital status, familial status, 

parental status, religion, sexual orientation, genetic information, political beliefs, reprisal, or because all or 

part of an individual’s income is derived from any public assistance program. (Not all prohibited bases apply 

to all programs.) Persons with disabilities who require alternative means for communication of program 

information (Braille, large print, audiotape, etc.) should contact USDA’s TARGET Center at (202) 720-2600 

(voice and TDD). To file a complaint of discrimination, write USDA, Director, Office of Civil Rights, 1400 

Independence Avenue, S.W., Washington, D.C. 20250-9410, or call (800) 795-3272 (voice) or (202) 720-6382 

(TDD). USDA is an equal opportunity provider and employer.

published by:

USDA Forest Service

Pacific Northwest Region (R6)

Portland, Oregon

FS-R6-RO-FIDL#11/003-2009

Successful infested-tree removal projects 

were conducted in the Lake Tahoe Basin 

Management Unit, Lassen Volcanic 

National Park and on the Lassen and 

Tahoe National Forests during the late 

1980’s and early 1990’s. Subsequent 

mortality was reduced in all areas when 

trees were removed prior to beetle 

emergence. If tree removal is not possible, 

infested trees may also be cut and burned 

or chipped to kill beetles.

Additional Information

Private landowners can get information 

from County Extension Agents, State 

Agricultural Departments, or their local 

State Forestry office. Federal resource 

managers contemplating action against the 

Jeffrey pine beetle should contact Forest 

Health Protection, USDA Forest Service 

(www.fs.fed.us/foresthealth/). This 

publication and other Forest Insect and 

Disease Leaflets (FIDLs) can be found at 

www.fs.fed.us/r6/nr/fid/wo-fidls/.

Six, D.L., and T.D. Paine. 1997. 

Ophiostoma clavigerum is the mycangial 

fungus of the Jeffrey pine beetle, 

Dendroctonus jeffreyi. Mycologia, 

89:858-866.

Smith, R.H. 1982. Log bioassay of residual 

effectiveness of insecticides against bark 

beetles. Res. Paper PSW-168. Berkeley, 

CA: USDA Forest Service, Pacific 

Southwest Forest and Range Experiment 

Station. 8 p. 

Acknowledgments

This revision is based on an earlier 1956 

version by Charles B. Eaton, deceased, 

and a 1971 version by Richard H. Smith. 

Critical reviews were provided by Brian 

Strom, Andris Eglitis and Ed Holsten. 

Assistance with layout and publication 

was provided by Mike Hamel. Kathy 

Sheehan is greatly appreciated for her 

work in maintaining the FIDL website and 

coordinating FIDL printing.

Figure Credits

Figures 1, 2, 4, 5, 6, 8, 9, 10: Sheri Smith, 

USDA Forest Service, Forest Health 

Protection, Pacific Southwest Region. 

Figure 3: Zachary Heath, USDA Forest 

Service, Forest Health Protection, Pacific 

Southwest Region. Figure 7: Erich Vallery, 

USDA Forest Service, Southern Research 

Station.

Pesticides used improperly can be injurious to humans, animals, and plants. 

Follow directions and read all precautions on the labels. Consult your local 

forest health specialist, county agricultural agent, or State extension agent 

about restrictions and registered uses of particular pesticides.