Bug FAQOak Artichoke Gall Wasp
Andricus foecundatrix · Order: Hymenoptera · Family: Cynipidae
Also called: Artichoke Gall
Source: Wikipedia
The oak artichoke gall wasp creates large, oval galls on oak buds that can reach about 2 cm in length and are covered in long whitish hairs when young. The wasp lives inside the gall, feeds on the nutritious tissue of the bud, and the adult females emerge in spring to lay eggs that cause the next generation of hairy catkin galls.
Source: Wikipedia
How to recognize it
Young galls have a tuft of long, whitish hairs sticking out from the centre of the artichoke shape.
Source: Wikipedia
Size
A mature gall can be up to 2 cm long, while the smaller hairy catkin galls are about 0.3 cm long.
Source: Wikipedia
Is it a pest in the house?
Even when many galls appear on scrub oaks, they cause no measurable damage. Removing and destroying galls before they dry can reduce the local wasp population.
Source: Wikipedia
How to get rid of it
Destroying galls before the adult emerges helps keep their numbers low.
Source: Wikipedia
What it eats
The gall provides both shelter and food for the developing wasp larvae, consisting of starch-rich bud tissue.
Source: Wikipedia
Life cycle
Females emerge from the oak artichoke gall in spring, lay a single egg in male oak flowers, which induces the formation of the hairy catkin gall; the adult may emerge the next spring or wait 2 to 3 years.
Source: Wikipedia
When you see it
After August the gall is just a distorted bud that has fallen, no longer a living structure.
Source: Wikipedia
Where it comes from
The species is currently called Andricus foecundatrix.
Source: Wikipedia
Lookalikes
A similar gall on yew is caused by the fly Taxomyia taxi, not by this wasp. Andricus curvator, which makes the collared-bud gall, often lays eggs on buds already used by A. foecundatrix.
Source: Wikipedia
More photos
Questions people ask
How can I get rid of oak artichoke gall wasps?
Remove and destroy the galls before they dry and the adult wasps emerge.
Source: Wikipedia
Are the galls harmful to my oak trees?
The galls cause no measurable harm to the trees.
Source: Wikipedia
Same family (Cynipidae)
Sources
- Wikipedia: https://en.wikipedia.org/wiki/Andricus_foecundatrix
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.