Andricus coquilletti

Identification of Andricus coquilletti requires examination of the specific gall morphology it induces on oak hosts, as adult wasps are minute (typically 2-4 mm) with reduced morphological differentiation between closely related species. The galls produced by this species would be distinguishable from those of congeners such as Andricus palustris by their specific location on the plant (leaf blade, petiole, or vein), size, shape, and surface texture. Adult specimens may be identified through microscopic examination of antennal segmentation, wing venation patterns, and genitalia structure, ideally by comparison with type specimens.

Found in habitats supporting oak species (Quercus), including deciduous woodlands, mixed forests, savannas, and urban parks with mature oak trees. The presence of suitable host oaks is the primary habitat requirement.

Distribution corresponds to the range of its oak host species; specific range records are limited in available sources but the genus Andricus is broadly distributed across North America, Europe, and Asia with highest diversity in temperate regions.

Adult emergence timed to coincide with oak leaf flush in spring; galls visible on developing leaves from late spring through summer. Specific phenology data for this species is not documented in available sources.

Larvae feed on nutritive tissue within the gall induced on oak leaves. Adults are not known to feed extensively, though some cynipids may consume honeydew or nectar.

• Quercus - gall hostSpecific oak host species not documented in available sources

Females deposit eggs into developing oak leaf tissue using a slender ovipositor. The egg-laying event and subsequent larval secretions induce localized plant cell proliferation, forming a gall that encloses the developing larva. The larva grows within the gall, feeding on specialized nutritive plant tissue, and pupates within a chamber inside the gall. Adults emerge from the gall to seek mates and oviposition sites. Many Andricus species exhibit complex heterogonic life cycles with alternating sexual and asexual generations that may produce different gall types, though this has not been explicitly documented for A. coquilletti.

As a gall inducer, modifies oak leaf architecture and creates microhabitats that may be exploited by inquilines (other insects that inhabit galls without inducing them) and parasitoids. The galls represent a significant sink for plant resources and may influence leaf-level photosynthesis and tree fitness, though typically without causing severe host damage.

Of minor direct economic importance; oak galls generally do not require management intervention. The species may be encountered by arborists, foresters, and naturalists observing oak trees.

• Andricus palustrisAlso induces spherical galls on pin oak leaves; differentiation requires examination of gall size, surface texture, and specific location on leaf or petiole, or microscopic identification of adult specimens
• Other Cynipidae on QuercusNumerous congeners and related genera (e.g., Neuroterus, Cynips) induce galls on oaks; precise identification relies on gall morphology and host tissue specificity

• gall wasp
• Cynipidae
• oak gall
• Quercus
• parasitoid
• plant-insect interaction
• cecidogenesis
• Hymenoptera

• BugGuide
• iNaturalist taxon
• Bembicid Holdings | Entomology Research Museum
• Bug Spotlight | Entomology Research Museum
• Primary Type List | Entomology Research Museum
• Field Guide Selected References
• Gall darn it! Gall insects on hickory, oak, and elm, Phylloxera caryaecaulis, Andricus palustris, Colopha ulmicola — Bug of the Week
• Bug Eric: Wasp Wednesday: Poecilopompilus algidus