Eucalyptus longhorned borers: what the agencies record

This page reports what the official source says. It is not legal advice: ask the office named here. It does not identify what is wrong with any tree and does not say what should be done about one. Two closely related beetles in the longhorned beetle family, Phoracantha semipunctata and Phoracantha recurva, bore under the bark of eucalyptus trees. Each section names its source, all read on October 9, 2026. The parent page, insect pests of trees, compares them with the other pests on the list.

Names and arrival in California

The University of California Statewide Integrated Pest Management Program, called UC IPM, says P. semipunctata is native to Australia and was introduced into Southern California in the 1980s. The University of California Riverside Center for Invasive Species Research, called CISR, dates the first find to Orange County in 1984. UC IPM says it then appeared throughout the state wherever eucalyptus grows. Both sources say a second species, P. recurva, was found in 1995 in Southern California, in Los Angeles, Riverside and San Bernardino counties per CISR, and in those three plus Orange County per UC IPM. UC IPM says it has since spread through much of the state.

The two species side by side

Point	P. semipunctata	P. recurva
Wing covers (UC IPM)	Mostly dark brown, with a zigzag line across the cream-colored middle	Mostly cream to yellowish, with dark brown limited mainly to the rear third
First found in California	1984, Orange County (CISR)	1995, Southern California (CISR, UC IPM)
Biological control	CISR: an egg parasitoid wasp from Australia, imported in 1992 and established by 1993, is credited with greatly reducing damage	CISR and UC IPM: biological control has been less effective
Life cycle (UC IPM)	Two and possibly three overlapping generations a year	Develops faster, with adults present for a longer part of the year and emerging as early as February

Size, hosts and what attracts them

CISR describes the beetles as large, often more than an inch long, with prominent long antennae. UC IPM says the antennae are as long as or longer than the body and that male antennae carry prominent spines. Both sources name eucalyptus as the host. CISR says about 90 of the more than 700 eucalyptus species have been brought to North America. Both sources say the beetles are drawn to freshly cut eucalyptus wood, dying limbs and trees under stress, especially water stress. UC IPM adds that eucalyptus species from wetter parts of Australia were planted in California, and that trees without irrigation are seasonally water stressed in hot summers. It says vigorous, suitably watered trees are usually left alone, and that species with some resistance can answer an attack with large amounts of resin.

Life cycle as the sources state it

UC IPM says P. semipunctata females lay eggs in groups of 3 to 30 under loose bark or in bark crevices, can live a month or more and can lay up to 300 eggs, which hatch in about 1 to 2 weeks. Larvae bore into the inner bark or feed briefly on the surface first, leaving a dark trail from 1/4 inch to several inches long. Most feeding is in the cambium, and tunnels can run several feet. Larvae need about 70 days in fresh wood in hot summer months and up to 180 days in drier logs, and UC IPM says only fairly fresh logs support them. Before pupating they cut a chamber in the wood and pack the entry with frass. In spring and summer a generation takes 3 to 4 months; from fall it can take up to 9 months. UC IPM says larvae can be present at any time of year and adults can emerge from April through October. CISR gives 2 to 3 generations a year in California and says feeding by many larvae can be heard from some distance.

Signs and damage as described

UC IPM lists holes in the bark and stains or oozing liquid on limbs or trunks as common symptoms, along with discolored, wilting foliage and limb dieback. It says larval feeding can spread around the whole circumference and girdle the trunk. Trees at that stage have a thin canopy with wilted or dry leaves and cracked bark packed with larval frass, and UC IPM says they usually die within a few weeks of girdling, though sprouts can come from the base. CISR gives the same mechanism: the cambial layer is ringed, so water and nutrients can no longer move from roots to leaves. CISR also notes that larvae suffer high mortality in trees with high internal moisture, because water floods the tunnels.

A change between the two species

CISR reports that the egg parasitoid kills up to 90 percent of P. semipunctata eggs laid under bark, but does not kill P. recurva eggs as effectively. It says the control of the first species reduced competition and let P. recurva become a more serious pest, with that species making up 0.1 percent of beetles in field samples in 1995, 4.7 percent the following year and 74 percent in 1997. UC IPM says P. recurva, along with several other new pests, can stress and kill eucalyptus.

Where they are recorded

CISR says P. semipunctata has been carried into virtually all eucalyptus-growing regions of the world and names Brazil, the Canary Islands, Chile, Egypt, France, Israel, Italy, Morocco, Reunion Island, Spain and South Africa. EPPO's Global Database, whose distribution pages were last updated January 23, 2026, lists P. semipunctata as present and widespread in Australia, South Africa, Zimbabwe, Chile, Uruguay, Israel and Portugal, and present in the United States with restricted distribution, California named. It lists the Netherlands as absent because the pest is no longer present, and Sweden and Switzerland as absent with interceptions only. For P. recurva EPPO lists Australia as widespread and Papua New Guinea as widespread, the United States as restricted distribution with California named, and Spain, France, Greece and Cyprus as few occurrences. EPPO marks a New Zealand record for P. recurva as absent, invalid record.

Regulated status

None of these sources gives a California or United States quarantine for either beetle. EPPO's categorization page for P. semipunctata lists it on the A1 list of Bahrain from 2003, as a quarantine pest of China from 2021, on the A1 list of the code CAN from 1992 and the A2 list of the code IAPSC from 1989. It also records an earlier EPPO A1/A2 listing from 1975 that was removed in 1999. For P. recurva EPPO records only a former place on the EPPO Alert List, added in 2003 and removed in 2006. For where to send reports of unfamiliar pests in the United States, see reporting a pest in the United States.

Management as the sources list it

UC IPM says the same approach covers both species: reducing tree stress, handling eucalyptus wood so it stops attracting egg-laying beetles, planting resistant species and not disrupting biological control, and that pesticide applications generally are not effective. It lists wood handling steps such as removing bark and chipping or solarizing infested wood, and a table of species by susceptibility. This page gives no timings, products or step lists. For rules on moving wood, see moving wood in California.