Zapatella davisae

Zapatella davisae can be distinguished from other oak gall wasps by its association with black oak (Quercus velutina) and the specific gall morphology it produces on stems. The species was formally described in 2016, separating it from previously misidentified or undescribed Zapatella species. Identification to species level typically requires examination of adult morphological features; DNA barcoding has been used to confirm parasitoid associations and may aid in distinguishing closely related species.

Mature black oak (Quercus velutina) forests in the northeastern United States. Larvae develop beneath bark on stems and branches.

Northeastern United States: Long Island, New York; Cape Cod, Martha's Vineyard, and Nantucket, Massachusetts; coastal Rhode Island. The species' range is actively expanding, with newer infestations documented in Nantucket, MA and coastal Rhode Island following initial outbreak areas.

Larvae develop under bark in late summer; adults emerge in early spring.

Phytophagous; feeds on black oak (Quercus velutina).

• Quercus velutina - primary host plantGall formation and larval development occur on stems and branches of black oak. This is the only confirmed host plant.

Larvae develop under bark in late summer; adults emerge in early spring. The sexual/asexual status of populations remains uncertain; genetic studies found significant deviations from Hardy–Weinberg equilibrium and excess clonal individuals, but were inconclusive regarding the Meselson effect due to limited sampling.

Forms stem galls on black oak. During population outbreaks, causes extensive foliar damage including flagging, leaf clumping, and limb loss. Population dynamics are strongly influenced by parasitism; near-total population collapse has been observed following high parasitism rates.

Herbivore capable of causing significant tree mortality and canopy damage during outbreaks. Serves as host for a parasitoid community dominated by Sycophila species, particularly S. nr. novascotiae and S. foliatae. Parasitism rates appear to regulate population densities, with lag effects observed in newly invaded regions where natural enemy communities may be less established.

Significant forest pest causing extensive damage and mortality to black oak trees, with economic and ecological impacts on northeastern U.S. oak forests. Management concerns focus on predicting spread and impact in newly invaded areas.

• Other Zapatella speciesCongeneric oak gall wasps; Z. davisae distinguished by host specificity to Quercus velutina and formal description in 2016
• Other Cynipini on QuercusMany oak gall wasps share similar life histories; identification requires host association and gall morphology examination

• gall wasp
• forest pest
• oak
• invasive
• parasitoid
• Cynipidae
• outbreak
• Quercus velutina
• northeastern United States

• BugGuide
• iNaturalist taxon
• NCBI Taxonomy
• Development of microsatellite markers for an outbreaking species of oak gall wasp,Zapatella davisae(Hymenoptera: Cynipidae), in the northeastern United States
• Life History and Potential Hosts of Zapatella davisae (Hymenoptera: Cynipidae), a Recent Invader on Black Oak in the Northeastern United States
• Identification of the parasitoid community associated with an outbreaking gall wasp,Zapatella davisae, and their relative abundances in New England and Long Island, New York