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How to identify it
- Adults are about 0.2 inch (5 mm) long. New adults are light brown and darken to black as they mature. The rear of the wing covers carries five small spines on each side.[1]
- Females measure 4.0 to 4.7 mm. Males have a split bump in the middle of the face just above the mouthparts, which separates them from other five-spined Ips.[2]
- It looks very much like pinyon ips. On the Arizona fivespined ips, the gap between the first and second spines is about twice as wide as on pinyon ips, and pinyon ips usually stays in pinyon pines.[1]
- Signs on the tree: within a few weeks of attack the needles at the top of the crown fade to light straw color, and the fading spreads until all needles are yellow or yellowish-brown. Tan to reddish-brown boring dust collects in bark crevices and at the base of the tree, and small mounds of it show up on infested slash.[1]
Look-alikes
| Look-alike | How to tell them apart |
|---|---|
| Pinyon ips (Ips confusus) | Nearly identical, with the first two declivity spines closer together; normally confined to pinyon pines.[1] |
| Pine engraver (Ips pini) | Also attacks ponderosa pine in the Southwest but is usually less aggressive in killing live trees in low to mid elevation Arizona stands.[1] |
| Western pine beetle and other Dendroctonus | Dendroctonus species also attack Southwest ponderosa pine but tend to infest the lower trunk, while Ips attack the tops of larger pines.[1] |
Where it lives
Southern Utah south through Mexico and Guatemala to Honduras. Economically important damage in the United States is mostly limited to Arizona, where ponderosa pine is the main host and Chihuahua pine has also been attacked in the Chiricahua Mountains; few beetles occur above 8,000 feet. A 2019 identification key lists United States records from Arizona and New Mexico.[1][2]
Biology and life cycle
At low to mid elevation ponderosa pine sites in Arizona (5,250 to 6,750 feet) there are typically three generations a year. Overwintered adults come out in March or April, the next flight follows in mid-June to early July, and a third generation starts in mid-August and usually stays under the bark until spring, although beetles have been trapped flying into mid-November at the lowest sites.[1]
A male bores through the bark and makes a nuptial chamber, and one to five females, usually three, join him. Each female cuts an egg gallery up to 25 inches long, keeps it clear of frass and lays eggs along both sides; summer eggs hatch in about a week. The legless larvae feed on the inner bark in side galleries running at right angles to the egg gallery and pupate between the inner and outer bark.[1]
The beetles prefer freshly cut slash. Live trees are attacked when beetle numbers are high and trees are stressed, for example after an extremely dry winter.[1]
Natural enemies include predatory checkered beetles and trogositid beetles, small parasitic wasps and internal nematodes that can cut a female's egg laying by as much as 50 percent. A few days at -5 degrees F or below kill many beetles, which may set the northern and upper elevation limits of the species.[1]
Damage and signs
- Attacks kill trees outright or kill their tops, and top-kill is common in trees of every size. An outbreak may take a few scattered pines or several thousand in groups.[1]
- Outbreaks usually follow prolonged drought or other stresses that weaken pine defenses. They also start where thinning or other work leaves lots of slash, especially on poor sites or where treatments run two or more years in a row.[1]
- Dying pines are not always this beetle. Pine engraver (Ips pini), Ips knausi, Ips calligraphus and several Dendroctonus bark beetles also attack ponderosa pine in the Southwest.[1]
Health risk
A pine pest; the Forest Service leaflet reports damage to trees only.[1]
Control
Prevention
Avoid creating pine slash for two or more seasons in a row, especially in low-elevation ponderosa pine in central and southern Arizona. If you thin or cut trees, do it from July to December: those trees dry out over fall and winter and are generally unsuitable for the beetles the next year. Late summer or early fall is best.[1]
Sanitation
Treat or remove slash larger than 4 inches in diameter; few beetles come out of smaller pieces. Cutting slash into pieces under 1 foot long has been shown to limit Ips brood in Arizona, and burning, chipping or burying green slash takes away breeding material. Do this within 30 days of cutting.[1]
Fresh chips give off odors that can draw bark beetles to the trees you kept. Chip from fall through early winter, when beetles are not flying, and rake or use tarps so chips do not pile up against tree trunks.[1]
Traps and physical control
Brood in infested wood 4 inches or more across can be killed under clear plastic: stack small piles of bolts in an open, sunny spot, cover them with plastic thicker than 6 mil and anchor it to the ground. The inside has to pass 113 degrees F, which deep or shaded piles may not reach. Debarking infested slash, or hauling it 3 miles or more from ponderosa pine stands, also works.[1]
Pesticides
Carbaryl and pyrethroid products are registered as preventive sprays for pines that have not been attacked, and should be used only after talking with a forest health professional. They are not recommended for trees already infested, and systemic insecticides are not recommended for prevention or cure.[1]
Common questions
- My pine's top turned straw-colored. Is it this beetle?
- Possibly. Fading that starts at the top of the crown, plus tan to reddish-brown boring dust in the bark cracks and at the base, fits this ips, but other Ips and Dendroctonus beetles cause similar symptoms in Southwest ponderosa pine, and not every tree with these signs is infested by this one.[1]
- Can I save a pine that is already infested?
- The leaflet does not recommend sprays for trees already infested. The focus is on protecting uninfested trees and dealing with the infested wood: burn, chip, bury, debark or solarize it, or move it at least 3 miles from ponderosa pine.[1]
- Is it safe to leave thinning slash on the ground?
- Pieces under 4 inches across produce few beetles. Larger slash left untreated is what this beetle breeds in, so handle it within 30 days and avoid making new slash two seasons running.[1]
Sources
- USDA Forest Service, Forest Health Protection (with University of Arizona Cooperative Extension), “Forest Insect & Disease Leaflet 116: Arizona Fivespined Ips, Ips lecontei Swaine, in the Southwestern United States (McMillin and DeGomez, revised December 2008).” www.fs.usda.gov/foresthealth/docs/fidls/FIDL-116-ArizonaFivespinedIps.pdf (accessed 2026-11-10)
- Canadian Journal of Arthropod Identification (Biological Survey of Canada), “Douglas, Cognato, Grebennikov and Savard. Dichotomous and matrix-based keys to the Ips bark beetles of the World: factsheet, Ips lecontei. Canadian Journal of Arthropod Identification 38 (2019), doi:10.3752/cjai.2019.38.” cjai.biologicalsurvey.ca/dcgs_38/factsheets/Ips_lecontei.htm (accessed 2026-11-10)
- iNaturalist, “Ips lecontei taxon page (order and family).” www.inaturalist.org/taxa/305538 (accessed 2026-11-10)