Andricus quercusstrobilanus

The galls of A. quercusstrobilanus are distinguished by their clustered, cone-shaped structure resembling a strobilus or pine cone, formed by multiple wedge-shaped segments radiating from a central point. This differs from other oak galls such as the round bullet galls of Disholcaspis quercusglobulus (single, detachable, round twig galls) or the various leaf galls produced by other Andricus species. The color progression from pink/red through yellow to brown is also characteristic.

Found in forests and woodlands supporting white oak species, including bur oak, swamp white oak, and overcup oak.

North America. Specific range details beyond this continental distribution are not well documented in available sources.

• Quercus alba - gall hostwhite oak
• Quercus macrocarpa - gall hostbur oak
• Quercus bicolor - gall hostswamp white oak
• Quercus lyrata - gall hostovercup oak

The life cycle involves adult females laying eggs in oak tissue, inducing gall formation. Larvae develop inside the gall wedges, feeding on the specialized plant tissue. The larva pupates within a hollow kernel inside each wedge. The specific timing of adult emergence and details of the sexual generation are not documented; cynipid wasps typically have complex alternating generations with sexual and asexual phases, but this has not been confirmed for A. quercusstrobilanus.

Larvae induce gall formation by secreting substances that manipulate plant growth hormones, causing the oak to produce the specialized cone-shaped gall structure. The galls are tightly clustered and break apart easily when dry.

The galls serve as a microhabitat supporting a community of associated insects. Guest wasps found in the galls include inquilines such as Synergus lignicola (Cynipidae), which inhabit the galls without inducing them, and parasitoids such as Eurytoma sp. (Eurytomidae), which attack the gall wasp larvae.

The galls are noticeable and distinctive structures that may attract attention from naturalists and entomologists. No economic significance to agriculture or forestry has been documented.

• Disholcaspis quercusglobulusAlso produces galls on white oaks, but forms single, round, detachable twig galls rather than clustered cone-shaped leaf or twig galls.
• Andricus dimorphusAnother Andricus species producing clustered galls on oaks, but forms midrib galls on leaves of chinquapin oak rather than cone-shaped structures.
• Andricus pattoniProduces galls on post oak leaves, but these are small, discrete structures on the leaf surface rather than large clustered cone-shaped galls.

• gall wasp
• Cynipidae
• oak gall
• inquilines
• parasitoids

• BugGuide
• Wikipedia
• iNaturalist taxon
• NCBI Taxonomy
• Gall darn it! Gall insects on hickory, oak, and elm, Phylloxera caryaecaulis, Andricus palustris, Colopha ulmicola — Bug of the Week
• Cynipidae | Beetles In The Bush
• The Insects Behind the Weird Growths on Plants
• Ted C. MacRae | Beetles In The Bush | Page 8