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How to identify it
- Adults are stout, cylindrical, dark brown to black beetles about 5/16 inch long, among the largest bark beetles.[1]
- Large, pink to dark-reddish pitch tubes holding boring dust and frass mark successful attacks, mostly on the middle of the trunk but also higher up and down to the ground. Creamy white to yellow tubes, often without dust, are usually failed attacks, where the tree pitched the beetles out.[1]
- Under the bark the egg galleries are mostly straight and run up the trunk, packed with frass, and usually hook into a J shape at the bottom; they are typically 10 to 40 inches long. Larval mines run across the grain and end in oval pupal cells.[1][2]
- Infested trees fade evenly through the crown from green to yellow to reddish brown, usually after the new beetles have already left. Trees attacked in early summer may fade by late fall; those attacked later often don't fade until the next spring or early summer.[1]
- In drought, stressed trees may not make pitch tubes, and boring dust in bark crevices and around the base may be the only visible sign.[1]
Look-alikes
| Look-alike | How to tell them apart |
|---|---|
| Mountain pine beetle | A close relative, similar in appearance and habit, that attacks ponderosa pine instead. Jeffrey pine has vanilla-scented bark, blue-green needles, red-brown under its bark scales, and 5- to 9-inch cones with spines that curve back; ponderosa pine has yellow-green needles, powdery yellow under its scales, and 3- to 6-inch cones with prickly, outward-pointing spines.[1] |
| Western pine beetle | Attacks ponderosa pine, not Jeffrey pine, and makes winding, sinuous galleries rather than straight J-shaped ones.[1] |
Where it lives
Its range follows Jeffrey pine, its only host, from the southern border of Oregon down through eastern California and into Nevada, south to the Sierra San Pedro Martir in Baja California. It has not been seen in the San Jacinto, Santa Rosa and Laguna mountains of southern California, although Jeffrey pine grows there.[1]
Biology and life cycle
Jeffrey pine is the only known host. Pole-size and larger trees are usually attacked, but during outbreaks any tree over about 4 inches in diameter can be killed.[1][2]
The female arrives first and bores in, the male joins her, and pheromones probably draw many more beetles to the same tree. Each pair bores diagonally across the grain for 2 or 3 inches, then straight up for another 2 to 3 feet, and the female lays pearly-white eggs in niches along the sides.[1]
Eggs hatch in one to three weeks. The larvae are curved, white, legless grubs with yellow heads; pupae turn into adults in about 10 days, and the new beetles chew out through the bark, leaving round exit holes.[1]
There are one or two generations a year: one is more common in northern California, and a second may develop in warmer areas such as southern California and Baja California. Most attacks happen in June and July but continue into early October, and the beetle overwinters mainly as larvae under the bark.[1][2]
The beetles carry a blue-stain fungus that discolors the sapwood within one to several months and helps kill the tree. More than 20,000 beetles can emerge from one large tree.[1]
The pine engraver, emarginate ips, red turpentine beetle and California flatheaded borer often attack the same trees. Clerid and ostomid beetles prey on the Jeffrey pine beetle, and woodpeckers feed heavily on it, leaving holes in the bark.[1]
Damage and signs
- It is the primary insect pest of Jeffrey pine. Large trees tend to die singly or in small groups, and big group kills of 10 to several hundred trees happen in pole-size stands.[1]
- Outbreaks follow drought: California had outbreaks in 1965-66, 1976-81 and 1992-94, and the 2002-2004 drought in southern California led to high mortality. Dense stands, many now crowded with white fir, leave large pines short of water in dry years.[1]
- It will attack fire-injured trees, but outbreaks afterward within the burn or in nearby uninjured trees are not common.[1]
Health risk
The Forest Service and UC IPM describe it only as a pest of Jeffrey pine; neither mentions any risk to people or pets.[1][2]
Control
Prevention
Healthy, uncrowded trees resist attack. Thinning dense stands is the only treatment that builds long-term resilience to drought and bark beetles; in landscapes, irrigate properly and avoid compacting soil or injuring roots and trunks.[1][2]
When thinning, treat fresh stumps with a registered borate product within 4 hours of cutting to prevent annosus root disease.[1]
Sanitation
Removing infested trees before the new beetles emerge reduced later losses around Lake Tahoe and in Lassen and Tahoe national forests; if removal isn't possible, infested trees can be cut and burned or chipped to kill the beetles.[1]
When to call a professional
Preventive insecticide sprays are reserved for high-value trees, such as those on private property. The trunk is sprayed to saturation at least to mid-trunk, 30 to 40 feet, before attack, and protection lasts 1 to 2 years. UC IPM notes these bark sprays are not available to home users and won't save a heavily infested tree.[1][2]
Common questions
- My pine has reddish pitch tubes on the trunk. Is it Jeffrey pine beetle?
- If the tree is a Jeffrey pine and the tubes are pink to dark red with boring dust in them, Jeffrey pine beetle is likely; creamy white or yellow tubes without dust are usually attacks the tree fought off.[1]
- How do I know it's a Jeffrey pine and not a ponderosa?
- Jeffrey pine bark smells like vanilla, its needles are blue-green, and its cones are 5 to 9 inches long with spines that curve back, unlike the prickly, outward-pointing spines on ponderosa pine cones.[1]
- Can spraying save my tree?
- Only as prevention, before beetles attack; sprays won't save a heavily infested tree, and the effective bark sprays are applied by professionals.[2][1]
Sources
- USDA Forest Service, “Jeffrey Pine Beetle (Forest Insect & Disease Leaflet 11, revised June 2009).” www.fs.usda.gov/foresthealth/docs/fidls/FIDL-11-JeffreyPineBeetle.pdf (accessed 2026-11-08)
- University of California Statewide IPM Program, “Pest Notes: Bark Beetles (Publication 7421).” ipm.ucanr.edu/PMG/PESTNOTES/pn7421.html (accessed 2026-11-08)
- iNaturalist, “Dendroctonus jeffreyi taxon page (order and family).” www.inaturalist.org/taxa/50257 (accessed 2026-11-08)