Bug FAQMarbled Cellar Spider
Holocnemus pluchei · Order: Araneae · Family: Pholcidae
Source: Wikipedia
Marbled cellar spiders are about 5 to 7 mm long, with long fragile legs that have black and white rings at the joints. They live in homes, building webs in attics, basements, eaves, under rocks or on walls, and are now common in Southern California as an urban pest. They eat insects such as fruit flies, houseflies and damselflies, and can live up to a year in the lab.
Source: Wikipedia
Size
Males are 5 to 7 mm and females are 5 to 7.5 mm long.
Source: Wikipedia
Is it a pest in the house?
They are a common household spider and are considered an urban pest in Southern California.
Source: Wikipedia
Does it bite or sting?
Although they are venomous, their fangs cannot deliver a strong bite, so they are not dangerous to humans.
Source: Wikipedia
Where it lives
They build nests in attics, basements, eaves, under rocks, on walls of buildings, and under eaves of houses.
Source: Wikipedia
What it eats
They prey on insects such as fruit flies, houseflies and damselflies.
Source: Wikipedia
Life cycle
In laboratory conditions they can live up to one year.
Source: Wikipedia
Where it comes from
They are native to the Mediterranean region of Europe and northern Africa.
Source: Wikipedia
Where it is found in the US
Recorded in 24 of 51 states and DC. Most records: California, Texas, Oregon, Arizona, Maryland, Utah, Nevada, Washington.
Darker = more records. Counts are museum and citizen-science records, not population size.
Source: GBIF
Status: introduced in North America; introduced in United States; introduced in Canada. Source: iNaturalist
Months it is reported in the US
Source: GBIF
More photos
Questions people ask
Where in my house might I find them?
They often make webs in attics, basements, eaves, under rocks or on walls.
Source: Wikipedia
What do they eat?
They feed on insects like fruit flies, houseflies and damselflies.
Source: Wikipedia
Are they a problem in Southern California?
Yes, they are now commonly found there and are considered an urban pest.
Source: Wikipedia
Same family (Pholcidae)
Sources
- Wikipedia: https://en.wikipedia.org/wiki/Holocnemus_pluchei
Look it up elsewhere: GBIF · iNaturalist · BugGuide · ITIS · Wikipedia
Text written 2026-10-23 from the sources above and checked sentence by sentence against them. Data fetched 2026-10-22.