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How to identify it
- Adults are 2.5 to 4.7 mm long and dark brown to black, with a densely hairy face. The wing covers are about 1.6 times longer than wide and round off at the rear, and the hairs along the middle of that sloping rear are very short and nearly all the same length.[1]
- Length of those hairs on the rear slope of the wing covers is the most reliable feature separating these beetles from western pine beetles to the west; genitalia shape also differs. In practice, location sorts them: the two species are separated by the Great Basin, Mojave and Sonoran Deserts.[2][1]
- Pitch tubes, small masses of resin mixed with boring dust around entry holes on the bark, are the easiest early sign. They are 1/4 to 1/2 inch across and creamy white to brownish red. Sometimes there is only boring dust, when the tree can no longer push out resin.[1]
- Under the bark the adult galleries wind across the trunk.[1]
Look-alikes
| Look-alike | How to tell them apart |
|---|---|
| Western pine beetle (Dendroctonus brevicomis) | Its sibling species west of the Great Basin, separated in 2019; western populations have longer hairs on the rear slope of the wing covers and respond more to exo-brevicomin than endo-brevicomin.[2][3] |
| Arizona fivespined ips (Ips lecontei) | Pine engravers such as this one top-kill ponderosa pines, and top-killed trees are more open to southwestern pine beetle attack.[1] |
| Roundheaded pine beetle (Dendroctonus adjunctus) | A common associate in the same ponderosa pine stands, along with mountain pine beetle.[1] |
| Mountain pine beetle (Dendroctonus ponderosae) | Another associate that can compete with southwestern pine beetle for the same trees.[1] |
Where it lives
Arizona, Colorado, New Mexico, Nevada, Utah and Texas, and the Mexican states of Chihuahua, Coahuila, Durango, Nuevo Leon and Tamaulipas, with the largest impacts in Arizona, New Mexico and Texas. Ponderosa pine is the main host; pinyon pine and Rocky Mountain Douglas-fir are occasional hosts. iNaturalist still files these beetles under western pine beetle, Dendroctonus brevicomis.[1]
Biology and life cycle
There are generally three generations a year, with beetles active from April to October and broods overlapping. In spring and summer the egg-to-adult cycle takes about 50 to 60 days: eggs hatch in 7 to 10 days, larvae feed 3 to 4 weeks, first in the phloem and then in the outer bark, and pupation lasts about a week. Winter is spent as larvae and pupae, stretching that generation to about 8 months.[1]
Females find a tree, probably by its odor and silhouette, and release the aggregation pheromone endo-brevicomin as they bore in; males answer with frontalin, and together with resin odors from the wounded tree this draws a mass attack. Mated pairs then give off verbenone and trans-verbenol, which tell other beetles to stay away.[1]
Eastern (southwestern pine beetle) females produce relatively more endo-brevicomin than western pine beetle females, and in field trapping eastern beetles were more attracted to endo- than exo-brevicomin, the reverse of western beetles.[3]
Woodpeckers flake off bark to eat larvae, pupae and adults. A trogositid beetle, Temnoscheila virescens, is an important predator, and a parasitoid wasp and a nematode are known parasites.[1]
Damage and signs
- Trees die after a mass attack because larvae and adults girdle the phloem and beetle-carried fungi block the water-conducting wood. Needles turn light yellow-green, then red or reddish brown, then drop, over weeks to months; hot, dry weather speeds this up.[1]
- Mostly creamy-white pitch tubes with no boring dust suggest the attacks failed and the tree will survive.[1]
- Dense ponderosa pine stands with trunks 8 to 20 inches in diameter are the most susceptible. Drought is likely the biggest trigger for outbreaks, and pines weakened by fire (moderately injured trees most of all), lightning or mechanical damage are favored.[1]
Health risk
A tree pest; the Forest Service leaflet describes harm to pines only.[1]
Control
Prevention
Thinning makes the remaining trees more vigorous and harder to colonize. Bringing stand density below 80 square feet of basal area per acre is expected to work best, though data for this species are limited and there are no thinning guidelines written specifically for it. Pines that survive a prescribed fire may be weakened and more open to attack for a while afterward.[1]
Sanitation
Removing or destroying infested trees, for example by taking off or damaging the bark, can hold down tree deaths over a few acres if most infested trees are treated. It has to be done before the new beetles emerge and fly.[1]
Pesticides
Several insecticides are registered to protect pines from bark beetles: bole sprays of bifenthrin, carbaryl or permethrin, or injections of emamectin benzoate formulations, applied before the tree is attacked. One application generally protects for one to three seasons. State regulatory agencies keep lists of registered products, and because little research has been done on this species specifically, consult a forest health professional first.[1]
A repellent blend called Verbenone Plus cut beetle catches in west Texas trials, and in a two-year test at the Davis Mountains Preserve, 27.4 percent of ponderosa pines died on treated plots compared with 52.4 percent on untreated plots. The leaflet notes it is not currently registered for operational use.[4][1]
When to call a professional
Landowners can get help from university cooperative extension offices, county agricultural commissioners, state natural resource agencies and the USDA Forest Service Forest Health Protection program.[1]
Common questions
- Is this just the western pine beetle?
- It was treated as the same species from 1963 until 2019, when differences in body hairs, genitalia, genetics and pheromones led researchers to separate it again. The two are split by the Great Basin and the southwestern deserts, so ponderosa pines from Arizona, New Mexico, Colorado, Utah and west Texas have this species.[1][2]
- My pine has pitch tubes. Will it die?
- Not always. Mostly creamy-white pitch tubes with no boring dust suggest the tree pushed the beetles out. Fading needles that turn yellow-green and then reddish after a heavy attack mean the tree has been killed.[1]
- Can I protect a valuable pine in my yard?
- Registered bole sprays or injections, applied before the tree is attacked, give one to three seasons of protection. Ask your state agency or extension office which products are registered where you live.[1]
Sources
- USDA Forest Service, Forest Health Protection, “Forest Insect and Disease Leaflet 192: Southwestern Pine Beetle (Gomez, Audley and Fettig, November 2025).” www.fs.usda.gov/foresthealth/docs/fidls/FIDL-192-SouthwesternPineBeetle.pdf (accessed 2026-11-10)
- Insects (MDPI), “Valerio-Mendoza, Garcia-Roman, Becerril, Armendariz-Toledano, Cuellar-Rodriguez, Negron, Sullivan and Zuniga. Cryptic species discrimination in western pine beetle, Dendroctonus brevicomis, based on morphological characters and geometric morphometrics. Insects 10 (2019) 377, PMID 31671535.” pubmed.ncbi.nlm.nih.gov/31671535/ (accessed 2026-11-10)
- Journal of Chemical Ecology (Springer), “Sullivan et al. Evidence for semiochemical divergence between sibling bark beetle species: Dendroctonus brevicomis and Dendroctonus barberi. Journal of Chemical Ecology 47 (2021) 10-27, PMID 33405044.” pubmed.ncbi.nlm.nih.gov/33405044/ (accessed 2026-11-10)
- Journal of Economic Entomology (Entomological Society of America), “Gomez, Audley, Fettig, Trainer, Mortenson, Davis, Wiseman and Mafra-Neto. Evaluation of a semiochemical tool for management of southwestern pine beetle, Dendroctonus barberi, in West Texas. Journal of Economic Entomology 119 (2026) 3496-3506, PMID 42380065.” pubmed.ncbi.nlm.nih.gov/42380065/ (accessed 2026-11-10)
- iNaturalist, “Dendroctonus barberi taxon page (order and family).” www.inaturalist.org/taxa/218218 (accessed 2026-11-10)