Bug FAQCommon Eucalyptus Longhorn
Phoracantha semipunctata · Order: Coleoptera · Family: Cerambycidae
Also called: Eucalyptus Longhorn Borer, Eucalyptus Longhorned Borer
Source: Wikipedia
Adults are dark brown to beige, about 1.5 to 2.3 cm long, with females slightly larger than males. The larvae feed inside the wood, destroying the cambium and can kill the whole tree.
Source: Wikipedia
How to recognize it
The beetle has a dark reddish body and a protruding spine at the rear.
Source: Wikipedia
Size
Adults measure roughly 15 to 23 mm (1.5 to 2.3 cm) in length, with females a bit larger than males.
Source: Wikipedia
Is it a pest in the house?
It is an invasive pest that harms introduced eucalyptus trees outside its native range.
Source: Wikipedia
Where it lives
They are most active at dusk in hot, dry regions where eucalyptus trees are abundant.
Source: Wikipedia
What it eats
Adults emerge in spring and summer evenings to feed on pollen and nectar of eucalyptus trees.
Source: Wikipedia
Life cycle
Larvae develop for up to 2.5 months, growing to 30 to 40 mm, cream-colored and legless.
Source: Wikipedia
When you see it
Adults are seen in spring and summer, becoming active in the early evening.
Source: Wikipedia
Where it comes from
The species is native to Australia.
Source: Wikipedia
Lookalikes
It looks similar to P. recurva but is larger and has more extensive dark markings.
Source: Wikipedia
Where it is found in the US
Recorded in 2 of 51 states and DC. Most records: California, Hawaii.
Darker = more records. Counts are museum and citizen-science records, not population size.
Source: GBIF
Months it is reported in the US
Source: GBIF
More photos
Questions people ask
How can I identify a Common Eucalyptus Longhorn?
Look for a dark reddish beetle about 1.5 to 2.3 cm long with a spine at the rear; females are slightly larger than males.
Source: Wikipedia
What trees does this beetle damage?
Its larvae feed inside eucalyptus trees, destroying the cambium and can kill the whole tree.
Source: Wikipedia
When are the adults active?
Adults appear in spring and summer and are most active during the early evening hours.
Source: Wikipedia
Is this beetle native to my area?
The species originates from Australia and is considered invasive where eucalyptus is introduced.
Source: Wikipedia
Same family (Cerambycidae)
House LonghornHylotrupes bajulusCan damage your home
Asian Longhorned BeetleAnoplophora glabripennisDamages trees, gardens or crops
Red Milkweed BeetleTetraopes tetrophthalmus
White-spotted SawyerMonochamus scutellatusCan damage your home
Red Pine Longhorn BeetleStictoleptura rubra
Spotted Longhorn BeetleRutpela maculataSources
- Wikipedia: https://en.wikipedia.org/wiki/Phoracantha_semipunctata
Look it up elsewhere: GBIF · iNaturalist · BugGuide · ITIS · Wikipedia
Text written 2026-10-24 from the sources above and checked sentence by sentence against them. Data fetched 2026-10-22.