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How to identify it
- Adults are reddish-brown to black beetles about 3 to 5.5 mm (1/8 to 1/4 inch) long. The rear of the wing covers is hollowed out and edged with five toothlike spines on each side.[1]
- Under the bark, the egg galleries usually form an inverted Y (a wishbone shape) with arms 4 to 6 inches long running with the grain, branching from a central chamber.[1][2]
- Early signs are reddish boring dust in bark crevices, in branch crotches and on cobwebs, or piled around entrance holes on cut logs and limbs. Pitch tubes are rare except on Coulter pine.[1]
- Infested pines fade from green to yellow, then orange, then reddish brown, and the sapwood of dying trees turns blue from a stain fungus the beetles carry.[1]
Look-alikes
| Look-alike | How to tell them apart |
|---|---|
| Western pine beetle and mountain pine beetle | These bark beetles often attack the trunks of pines that the California fivespined ips has already top-killed, so more than one beetle may be found in the same tree.[1] |
Where it lives
Found west of the crests of the Sierra Nevada and Cascade Mountains, from northern Oregon to southern California, from sea level to timberline.[1]
Biology and life cycle
Hosts are pines, including ponderosa, sugar, Coulter, western white, lodgepole, Jeffrey, knobcone, Monterey and bishop pines and knobcone-Monterey hybrids, and probably introduced pines planted within its range.[1][2]
Normally it attacks only scattered trees that are suppressed, diseased or injured, where the bark is 1/8 to 1 inch thick: saplings and pole-size pines 1 to 10 inches in diameter and the thin-barked tops of bigger trees. In outbreaks it kills trees up to 26 inches across, and it breeds in fresh slash of almost any size.[1]
The male bores a mating chamber in the inner bark and releases a pheromone that draws in more beetles of both sexes; enough of them can kill a small group of trees. Usually three females join each male, and each cuts an egg gallery.[1]
Eggs hatch in 5 to 14 days, larvae feed for 2 to 5 weeks, and the summer pupal stage lasts 1 to 2 weeks; near the middle of its range, at about 3,000 feet, one summer generation takes 45 to 60 days. More than half of the parent beetles often leave after about 20 days and attack fresh material to start a second brood.[1]
Cooler parts of the range usually have two spring and summer generations plus an overwintering one; warmer parts can have up to five, and generations overlap. In warm areas adults attack from mid-March to mid-November.[1][2]
Late-season attacks produce a brood that overwinters under the bark as mature larvae, pupae or adults.[1]
About 20 native parasitic and predatory insects attack it, along with mites, nematodes, woodpeckers and fungi, but they don't act fast enough to prevent outbreaks.[1]
Damage and signs
- The beetles kill trees or the tops of trees. The blue-stain fungus they introduce kills the tissue around the entrance holes so the tree can't push the beetles out with resin; enough attacks girdle the tree, and the crown dies quickly.[1]
- In summer, the needles begin to fade within a month of the first attack, and by the time the foliage fades the new beetles have often left. Trees attacked in late fall may not fade fully until the next spring.[1]
- Outbreaks are sporadic and seldom last more than a year. Widespread outbreaks occurred in California during the droughts of 1929-32, 1959-61 and 1975-77, and mortality usually drops the year after a drought.[1]
- Besides drought, storm damage, fire, lightning, flooding, crowding, root disease, dwarf mistletoe, and injuries from logging or construction make pines more likely to be attacked.[1]
Health risk
The Forest Service and UC IPM describe it only as a pest of pines; neither mentions any risk to people or pets.[1][2]
Control
Prevention
Keep landscape pines vigorous: water them properly during drought to avoid stress, and avoid compacting soil, injuring roots and trunks, or excavating, filling and paving near the root zone.[2][1]
UC IPM advises against pruning pines from February to mid-October, when the beetles are flying.[2]
Sanitation
Fresh pine slash, logs and firewood breed beetles, especially when cut between March and June. Keep them at least several yards from living trees, and don't pile unseasoned, freshly cut wood near landscape plants or move firewood to new areas.[1][2]
To keep cut pine from producing beetles, cut and chip it into small pieces, scatter limbs in the sun, or pile it in a sunny spot and cover it tightly with thick clear plastic; UC IPM suggests 10-mil plastic left in the sun for several months.[1][2]
Remove severely infested trees, or burn or treat them, before the new brood emerges.[2][1]
When to call a professional
Insecticides won't save a heavily infested tree. A valuable, uninfested pine can be protected by spraying the trunk, root collar and larger branches with a pyrethroid or carbaryl before beetles bore in; UC IPM notes these products are not available to home users, and the Forest Service suggests hiring a professional tree care service for trees recently stressed by fire, drought, flooding, transplanting or construction.[2][1]
Common questions
- Why is the top of my pine turning orange?
- Top-killing is typical of the California fivespined ips, which attacks the thin-barked tops of larger pines. Infested foliage fades from green to yellow, orange and then reddish brown.[1]
- Can I stack fresh pine firewood next to my trees?
- No. Fresh pine slash, logs and firewood are breeding material, and beetles emerging from them can attack nearby stressed trees; keep them at least several yards away.[1][2]
- Can spraying save a pine that is already dying?
- No. Insecticides won't save heavily infested trees; spraying is only a preventive for valuable trees that haven't been attacked yet, and the effective products are for professional applicators.[2]
Sources
- USDA Forest Service, “California Fivespined Ips (Forest Insect & Disease Leaflet 102).” www.fs.usda.gov/foresthealth/docs/fidls/FIDL-102-CaliforniaFiveSpinedIps.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, “Ips paraconfusus taxon page (order and family).” www.inaturalist.org/taxa/786881 (accessed 2026-11-08)