Callirhytis quercusoperator

The woolly catkin gall is distinctive among oak galls. The combination of: (1) location on catkins rather than leaves or stems, (2) fuzzy/woolly surface texture, and (3) association with oak (Quercus) hosts separates this species from Callirhytis quercuspunctata (gouty oak gall, which forms on twigs) and Callirhytis seminator (acorn plum gall, which forms on acorns). The gall's seasonal timing and succulent texture when young may help distinguish it from the harder, later-season galls of Callirhytis clavula.

Found in oak-dominated habitats including deciduous forests, woodlands, and areas with Quercus species present. The species requires access to flowering oak catkins for gall formation.

Documented from North America, with observations spanning multiple regions. The species has been recorded in northwestern Missouri and appears to have a broad distribution coinciding with its oak hosts.

Activity is tied to oak catkin development. Based on related species and the context of June observations in Missouri, the sexual generation likely emerges and forms galls in spring when catkins are present. The timing distinguishes it from fall-active generations of some related species.

• Quercus - gall inductionSpecific oak species not documented in sources; forms galls on catkins

Exhibits heterogony (alternation of generations) typical of Cynipidae, with sexual and parthenogenetic generations producing different gall types on different plant tissues. The woolly catkin gall represents one generation; the alternate generation and its associated gall form are not specified in available sources.

Females induce gall formation on oak catkins through oviposition. The gall provides nutrition and protection for developing larvae.

As a gall inducer, modifies oak reproductive structures (catkins), potentially affecting pollen production and seed set. Serves as a food source for gall-inhabiting parasitoids and inquilines, though specific associates are not documented.

No documented economic or medical significance. Of interest to naturalists and entomologists studying gall wasp diversity and oak ecology.

• Callirhytis quercuspunctataForms gouty oak galls on twigs rather than catkins; galls are woody and spherical, not woolly
• Callirhytis seminatorForms acorn plum galls on acorns, not catkins; gall is a single smooth swelling rather than woolly
• Callirhytis clavulaForms hard, woody galls in fall; lacks the succulent, woolly texture of C. quercusoperator galls
• Antistrophus spp.Induces stem galls on Silphium (rosinweed), not oak catkins; host plant and gall location differ

• gall wasp
• cynipid
• oak gall
• heterogony
• catkin gall
• Hymenoptera

• BugGuide
• iNaturalist taxon
• NCBI Taxonomy
• ID Challenge #3 | Beetles In The Bush