Bug FAQPriacma bleach beetle
Priacma serrata · Order: Coleoptera · Family: Cupedidae
Male Priacma bleach beetles are 9.6 to 12.5 mm long and are strongly drawn to bleach odor. They live under loose bark in coniferous forests of western North America, emerge as adults in irregular, large swarms, and have empty, withered guts as adults.
Source: Wikipedia
How to recognize it
Males are strongly attracted to the smell of bleach.
Source: Wikipedia
Size
Males range from about 9.6 mm to 12.5 mm in length.
Source: Wikipedia
Where it lives
They are found under loose bark in coniferous forests.
Source: Wikipedia
What it eats
Dissections of adult males show empty, withered intestines, indicating they do not feed as adults.
Source: Wikipedia
Life cycle
Adult emergence occurs in highly episodic, sporadic events that can involve large numbers of beetles.
Source: Wikipedia
When you see it
Collections show that adult emergence is irregular and occurs in sporadic bursts.
Source: Wikipedia
Where it comes from
The species is native to western North America.
Source: Wikipedia
Lookalikes
It is the only living species in the genus Priacma, so there are no close look-alikes.
Source: Wikipedia
Where it is found in the US
Recorded in 6 of 51 states and DC. Most records: California, Idaho, Oregon, Montana, Washington, Nevada.
Darker = more records. Counts are museum and citizen-science records, not population size.
Source: GBIF
Status: native in North America; native in Canada. Source: iNaturalist
Months it is reported in the US
Source: GBIF
More photos
Questions people ask
When do adult beetles appear?
Adults emerge in irregular, large swarms during sporadic events.
Source: Wikipedia
How big are Priacma bleach beetles?
Males measure between about 9.6 mm and 12.5 mm long.
Source: Wikipedia
Sources
- Wikipedia: https://en.wikipedia.org/wiki/Priacma_serrata
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 2026-10-24.