Oak-gall
Guides
Andricus quercusstrobilanus
lobed oak gall wasp, pine cone oak gall wasp
Andricus quercusstrobilanus is a gall wasp in the family Cynipidae that induces distinctive cone-shaped galls on white oaks in North America. The species name references both its oak host ('quercus') and the strobilus-like (cone-shaped) structure of the gall it produces. The galls are sometimes called 'pine cone oak galls' due to their appearance. Adults of this species have not been formally described.
Andricus reticulatus
Andricus reticulatus is a species of cynipid gall wasp in the family Cynipidae. Like other members of the genus Andricus, this species induces characteristic galls on oak (Quercus) host plants. Cynipid gall wasps are highly specialized insects with intimate evolutionary relationships with their host plants, typically forming species-specific gall structures that serve as both shelter and food source for developing larvae. The genus Andricus is one of the most diverse within the Cynipidae, with numerous species associated with various oak species.
Andricus robustus
Andricus robustus is a species of cynipid gall wasp in the family Cynipidae. Like other members of the genus Andricus, this species induces characteristic galls on oak trees (Quercus spp.). The specific gall morphology and host associations of A. robustus have not been extensively documented in the available literature. The species follows the typical cynipid life cycle involving an alternation of generations between sexual and asexual forms, though detailed studies of its biology remain limited.
Andricus sessilum
Andricus sessilum is a species of gall wasp in the family Cynipidae, a group known for inducing distinctive plant growths called galls on oak trees (Quercus spp.). Like other members of the genus Andricus, this species exhibits high host specificity, with females laying eggs in oak tissues to initiate gall formation. The developing larva secretes chemical signals that manipulate plant growth, creating a specialized structure that provides both food and shelter. Cynipid gall wasps are among the most diverse gall-forming insects, with each species typically producing a characteristic gall morphology on specific host plants or plant parts.
Andricus stellulus
stellar gall wasp
Andricus stellulus is a gall-inducing cynipid wasp that forms distinctive stellar galls on oak leaves. The species is known from arid regions of the southwestern United States, particularly the Mojave Desert of California, where it induces small, uniquely structured galls on scrub oak and shrub live oak. The galls consist of thin, hair-like stalks topped with toothed cups, representing one of the more architecturally unusual gall forms among the highly diverse Cynipidae.
Andricus stropus
leafy-wreath gall
Andricus stropus is a species of cynipid gall wasp in the family Cynipidae that induces distinctive galls on oak trees. The species is part of the highly diverse Andricus genus, which contains numerous oak-associated gall wasps, each producing characteristic gall structures. Like other cynipids, A. stropus has a complex life cycle involving manipulation of plant tissue through chemical secretions that redirect host oak growth patterns. The species is known from observations primarily in North America.
Andricus texanus
Andricus texanus is a species of gall wasp in the family Cynipidae, a diverse group of insects that induce characteristic growths on oak trees. Like other members of its genus, this species manipulates plant tissue to form specialized structures that provide shelter and food for developing larvae. The specific gall morphology and host associations distinguish it from related Andricus species.
Andricus tubularius
A cynipid gall wasp in the genus Andricus that induces distinctive galls on oak hosts. Like other members of this large and diverse genus, this species exhibits high host specificity and complex life cycles typical of oak gall wasps. The specific gall morphology and exact host associations for this species require further documentation.
Andricus vacciniifoliae
Golden Oak Apple Gall Wasp, Golden Oak Apple Wasp
Andricus vacciniifoliae is a gall-forming cynipid wasp native to the west coast of North America. The species creates distinctive stem galls on huckleberry oak (Quercus vacciniifolia) and canyon live oak (Quercus chrysolepis). The galls are colorful and fruit-like in appearance, often leading to misidentification as actual fruit. The wasp has been reclassified from Andricus to Trichoteras in some taxonomic treatments, though both names remain in use.
Andricus weldi
Andricus weldi is a species of cynipid gall wasp in the family Cynipidae. Like other members of this diverse family, it induces the formation of specialized plant galls on oak hosts. The species was named in honor of Lewis H. Weld, a prominent American cynipidologist who authored foundational works on gall wasps of the eastern United States. Specific details regarding its gall morphology, host associations, and biology remain limited in the available literature.
Andricus wheeleri
Andricus wheeleri is a species of gall wasp in the family Cynipidae. Like other members of this genus, it induces distinctive gall formations on oak host plants. The species is part of a highly diverse radiation of cynipid wasps that have evolved intimate associations with Quercus species. Specific details regarding its gall morphology and host relationships are not well documented in the available literature.
Antron
Antron is a genus of gall wasps in the family Cynipidae. These insects induce distinctive galls on oak trees (Quercus species), with the urchin gall induced by A. quercusechinus being particularly notable for its striking appearance. The genus belongs to the tribe Cynipini, which contains the majority of oak gall wasps. Species in this genus are specialized to specific oak hosts and gall locations.
Antron douglasii
Spined Turban Gall Wasp
A cynipid gall wasp that induces distinctive spined turban galls on oak leaves. The galls are characterized by their fleshy, pink to reddish appearance with bristly projections. This species is part of the highly diverse oak gall wasp fauna of western North America. The wasp manipulates plant tissue development through chemical cues, though the precise mechanism remains unknown.
Antron quercusechinus
urchin gall wasp
Antron quercusechinus is a gall-inducing cynipid wasp that induces the distinctive 'urchin gall' on oak trees. The gall is spherical, approximately 1.5 cm in diameter, and covered with prominent spines that give it a sea urchin-like appearance. The species primarily targets blue oaks (Quercus douglasii) but has been observed on other white oaks. Heavy infestations can produce thousands of galls on individual trees.
Antron quercusnubila
Antron quercusnubila is a gall-inducing cynipid wasp native to the southwestern United States. The species exhibits an alternating sexual and asexual generation cycle, a trait confirmed through molecular analysis of cytb and ITS2 sequences. Like other members of the Cynipidae, this wasp manipulates oak host tissue to form protective galls that shelter and nourish developing larvae.
Atrusca
Atrusca is a genus of gall wasps in the family Cynipidae, tribe Cynipini, comprising approximately 42 species distributed across North and Central America. These tiny wasps are specialized herbivores that induce characteristic galls on oak (Quercus) host plants. The genus forms a phylogenetically distinct clade most closely related to Cynips, Philonix, and Xanthoteras, and morphologically resembles Cynips and Antron. Species exhibit high host specificity, with each typically restricted to one or a few closely related oak species.
gall-waspCynipidaeoak-gallQuercusherbivoreparasitoidNorth-AmericaMexicoCentral-AmericaCynipiniinduced-gallplant-insect-interactionhost-specificityalternation-of-generationsasexual-reproductionsexual-reproductionecosystem-engineerinquilinehyperparasitoidbella-species-complexphylogeneticstaxonomyKinsey-1930Atrusca aggregata
Atrusca aggregata is a species of cynipid gall wasp described by Weld in 1926. Like other members of the family Cynipidae, this tiny wasp induces the formation of characteristic galls on oak leaves. The genus Atrusca is known for producing colorful, detachable leaf galls on various Quercus species. Adult females emerge from galls and use their ovipositor to inject eggs into leaf tissues, initiating the next generation of galls.
Atrusca brevipennata
little oak-apple gall wasp
Atrusca brevipennata is a cynipid gall wasp that produces distinctive galls on oak leaves in western North America. Formerly known as Andricus pellucidus, this species was first described by Gillette in 1893 and later studied by Alfred Kinsey. The wasp is locally common in the American Southwest, with records extending as far north as Denver. It oviposits into leaves of shrub live oak (Quercus turbinella) and Gambel oak (Q. gambelii), inducing the formation of small oak-apple galls. The species is visually similar to Atrusca bella and may be confused with it in the field.
Atrusca capronae
striped oak-apple gall wasp
Atrusca capronae, commonly called the striped oak-apple gall wasp, is a cynipid wasp species that induces characteristic galls on oak leaves in southwestern North America. The species is most frequently observed in Arizona but occurs throughout the region where its host plants grow. The wasp's common name derives from the striped appearance of the galls it produces, though stripe intensity varies geographically. The species is considered fairly common within its range.
Atrusca carolina
Atrusca carolina is a species of gall wasp in the family Cynipidae. Like other members of the genus Atrusca, this species induces galls on oak leaves. The genus is known for producing colorful and structurally distinctive galls on Quercus species. Specific details about A. carolina's biology, host associations, and distribution remain poorly documented in available literature.
Atrusca cubitalis
Atrusca cubitalis is a species of cynipid gall wasp, a group of tiny wasps known for inducing characteristic plant galls on their host plants. As a member of the family Cynipidae, this species exemplifies the highly specialized host relationships typical of gall wasps, where each species typically induces a distinct gall type on a specific host plant or closely related group of plants. The genus Atrusca is known for producing colorful and structurally distinctive galls on oak leaves (Quercus spp.), with A. cubitalis specifically associated with post oak (Quercus stellata) based on related species observations. The life cycle involves the female wasp using her ovipositor to inject eggs into leaf tissue, after which the developing larvae secrete plant growth hormones that cause the formation of a specialized gall structure within which they feed and develop.
Atrusca quercuscentricola
Spotted Oak Apple Gall Wasp
Atrusca quercuscentricola is a cynipid gall wasp that induces distinctive colorful galls on the leaves of post oak (Quercus stellata). The galls are particularly notable for their bright coloration and the presence of a visible adult emergence hole upon maturation. Like other cynipid gall wasps, the female lays eggs in leaf tissue using her ovipositor, and the developing larvae secrete plant growth hormones that cause the plant to form a specialized gall structure. The larva develops inside this gall, feeding on the plant tissue, before emerging as an adult through a chewed exit hole.
Atrusca unica
Atrusca unica is a species of cynipid gall wasp in the family Cynipidae. Like other gall wasps, it induces the formation of specialized plant structures called galls on its host plant. The genus Atrusca is known for producing colorful, prominent leaf galls on oaks (Quercus spp.). This species appears to be relatively well-documented with 227 observations on iNaturalist, suggesting it is not exceptionally rare, though specific details about its biology remain limited in the provided sources.
Bassettia
Bassettia is a genus of gall wasps in the family Cynipidae, restricted to North America. The genus was established by William Harris Ashmead in 1887, named in honor of H. F. Bassett, an amateur entomologist who contributed significantly to the study of gall wasps. As of 2007, the genus comprises nine recognized species distributed across the United States from Connecticut to California, with one species extending into Panama. These wasps induce galls on oak trees (Quercus species), with each species typically associated with specific host plants and geographic regions.
Bassettia flavipes
Bassettia flavipes is a gall wasp in the family Cynipidae that induces galls on oaks, particularly Quercus macrocarpa (bur oak). This species exhibits an alternation of generations between sexual and asexual forms, a trait now confirmed through molecular data. It was originally described from the sexual generation by Gillette in 1889 and was later transferred from the genus Neuroterus to Bassettia based on genetic and morphological evidence. The species is distributed across the northern United States and southern Canada.
Belonocnema
Belonocnema is a genus of cynipid gall wasps restricted to the southeastern United States. The genus comprises three recognized species that induce distinct galls on section Virentes oaks, including live oaks. All species exhibit heterogony, with alternating sexual and asexual generations producing morphologically and ecologically different gall types. The genus has been subject to taxonomic revision, with Dryorhizoxenus now synonymized under Belonocnema.
Burnettweldia californicordazi
Burnettweldia californicordazi is a species of oak cynipid gall wasp described in 2021 as the type species of the new genus Burnettweldia. The genus was established to accommodate five Nearctic species previously assigned to other genera or newly described. As a member of tribe Cynipini, this species induces galls on oak trees (Quercus spp.). The species name references California, indicating the geographic region of its type locality.
Burnettweldia corallina
Coral Gall Wasp
Burnettweldia corallina is a cynipid gall wasp that induces distinctive detachable galls on blue oaks (Quercus douglasii) in California. The species was formerly classified under the genera Disholcaspis and Holcaspis before its current placement in Burnettweldia. The wasp oviposits at the base of leaf petioles, and the resulting galls change color dramatically as they mature.
Burnettweldia plumbella
Beaked Twig Gall Wasp
Burnettweldia plumbella is a gall wasp that induces distinctive galls on oak trees. The species was transferred from the genus Disholcaspis to the newly erected genus Burnettweldia in 2021. It is commonly known as the beaked twig gall wasp due to the pointed tip of the galls it produces. The wasp has been documented on multiple oak species in western North America.
Burnettweldia washingtonensis
fuzzy gall wasp
Burnettweldia washingtonensis is a cynipid gall wasp that induces distinctive stem galls on white oaks (Quercus sect. Quercus) along the Pacific coast of North America. The species was originally described as Cynips washingtonensis in 1894 and later transferred to Disholcaspis before its current placement in Burnettweldia. It is locally common and among the more frequently observed oak gall wasps in its range, with over 1,400 citizen science records.
Callirhytis
Callirhytis is a genus of gall wasps comprising more than 90 described species, all members of the family Cynipidae. These wasps are specialized herbivores that induce the formation of galls on oak trees (Quercus spp.) in North America. The genus exhibits complex life cycles with alternating sexual and asexual generations, often producing morphologically distinct galls. Callirhytis species are among the most extensively studied cynipids due to their ecological importance and the structural diversity of their galls.
Callirhytis balanacea
Callirhytis balanacea is a species of cynipid wasp in the family Cynipidae, known for inducing pea-sized galls on oak trees. The species produces distinctive pip galls on oak hosts, which exude sugary secretions that serve as food sources for other insects. It has been documented as a gall-forming insect with specific ecological interactions, including serving as a food source for hairstreak butterflies that feed on gall exudates rather than nectar.
Callirhytis balanopsis
Callirhytis balanopsis is a species of gall wasp in the family Cynipidae. The species induces galls on oak hosts, continuing the genus's well-documented association with Quercus species. Like other Callirhytis species, it exhibits a complex life cycle with alternating sexual and asexual generations that produce distinct gall types. The specific epithet 'balanopsis' references the acorn-like appearance of its galls.
Callirhytis carmelensis
Mottled Acorn Gall Wasp
A cynipid gall wasp endemic to California that induces distinctive galls on acorns of coast live oak (Quercus agrifolia) and interior live oak (Quercus wislizeni). The galls form at the acorn attachment point, often preventing normal nut development. The species produces a honeydew secretion that attracts other insects. Despite being described in 1922, it remains uncommon and poorly studied relative to other California oak gall wasps.
Callirhytis clavula
Callirhytis clavula is a species of gall wasp in the family Cynipidae, known to induce galls on oak trees (Quercus). Like other members of the genus Callirhytis, it exhibits a complex life cycle involving alternating generations that produce different gall types on different plant tissues. The species is native to eastern North America, with records from Canada and the United States. Specific details of its gall morphology and biology remain poorly documented in the primary literature.
Callirhytis ellipsoida
Callirhytis ellipsoida is a species of gall wasp in the family Cynipidae. Like other members of its genus, it induces the formation of galls on oak hosts. The species exhibits the typical complex life cycle of oak cynipids, with alternating sexual and asexual generations that produce morphologically distinct galls.
Callirhytis elliptica
Callirhytis elliptica is a species of gall wasp in the family Cynipidae. The species is known to induce galls on oak hosts, consistent with the genus's well-documented association with oaks. As with other members of Callirhytis, this species exhibits the complex life cycles typical of cynipid gall wasps, often involving alternating sexual and asexual generations that produce different gall forms. Specific details regarding the morphology of its galls and precise host oak species remain limited in published sources.
Callirhytis favosa
Honeycomb leaf gall wasp
Callirhytis favosa is a gall wasp in the family Cynipidae that induces distinctive honeycomb-patterned galls on oak leaves. The species exhibits the complex life cycle typical of many cynipids, with alternating sexual and asexual generations that produce different gall types on different oak tissues. The specific epithet 'favosa' refers to the honeycomb-like appearance of the galls.
Callirhytis flavipes
Callirhytis flavipes is a species of gall wasp in the family Cynipidae. Species in this genus are known to induce galls on oak trees (Quercus spp.). The genus Callirhytis is part of the tribe Cynipini, which comprises the oak gall wasps. Specific biological details for C. flavipes remain poorly documented in accessible literature.
Callirhytis frequens
Callirhytis frequens is a species of gall wasp in the family Cynipidae. Members of the genus Callirhytis are known to induce galls on oak species (Quercus). The species exhibits the complex life cycle typical of many cynipids, with alternating sexual and asexual generations that often produce morphologically distinct galls on different oak tissues or species. As with most Callirhytis species, detailed natural history information for C. frequens remains limited in published literature.
Callirhytis furva
Callirhytis furva is a species of gall wasp in the family Cynipidae. Like other members of the genus Callirhytis, it induces galls on oak trees (Quercus spp.). The species exhibits the complex life cycle typical of many cynipid wasps, with alternating sexual and asexual generations that often produce distinct gall morphologies on different plant tissues.
Callirhytis gallaestriatae
Callirhytis gallaestriatae is a species of gall wasp in the family Cynipidae. As with other members of this genus, it induces galls on oak hosts (Quercus species). The species exhibits the complex life cycle typical of many cynipids, with alternating sexual and asexual generations that often produce morphologically distinct galls. The specific epithet "gallaestriatae" suggests association with galls bearing striations or stripes.
Callirhytis glandulus
Callirhytis glandulus is a species of gall wasp in the family Cynipidae. Like other members of the genus Callirhytis, this species induces the formation of galls on oak hosts (Quercus). The species was described by Beutenmüller in 1913. As with many Cynipidae, it likely exhibits an alternating generation life cycle with distinct sexual and asexual phases that produce different gall morphologies.
Callirhytis juvenca
Callirhytis juvenca is a species of gall wasp in the family Cynipidae. Like other members of its genus, it induces galls on oak hosts (Quercus species). The species exhibits the typical complex life cycle of cynipid gall wasps, with alternating sexual and asexual generations that often produce morphologically distinct galls. Specific details regarding its host associations and gall morphology remain limited in published literature.
Callirhytis lanata
Callirhytis lanata is a species of gall wasp in the family Cynipidae. It induces galls on oak species (Quercus), with specific host associations and gall morphology distinguishing it from congeners. The species exhibits the typical cynipid life cycle with alternating sexual and asexual generations that produce different gall forms.
Callirhytis pedunculata
Callirhytis pedunculata is a species of gall wasp in the family Cynipidae. Like other members of its genus, it induces galls on oak trees (Quercus species). The species exhibits the typical complex life cycle of cynipid gall wasps, with alternating sexual and asexual generations that often produce distinct gall morphologies on different oak tissues.
Callirhytis perdens
Ruptured Twig Gall Wasp
Callirhytis perdens is a gall wasp in the family Cynipidae that induces distinctive stem galls on several oak species in California. Unlike many gall wasps where larvae develop entirely within attached galls, this species exhibits a unique life history where mature larval capsules are expelled from fissures in the gall and complete development on the ground. The species was formerly classified under the genus Andricus. It is considered locally abundant within its restricted range.
Callirhytis perditor
Callirhytis perditor is a species of gall wasp in the family Cynipidae. Like other members of its genus, it induces the formation of galls on oak trees (Quercus species). The species exhibits the complex life cycle typical of many cynipid wasps, with alternating sexual and asexual generations that often produce morphologically distinct galls on different parts of the host plant.
Callirhytis perfoveata
leaf ball gall wasp
Callirhytis perfoveata is a cynipid gall wasp endemic to California that induces distinctive spherical leaf galls on oak trees. Formerly classified as Andricus perfoveata, this species specifically targets coast live oak (Quercus agrifolia), interior live oak (Q. wislizeni), and occasionally California black oak (Q. kelloggii). The galls form embedded within leaf tissue, appearing as roughly spherical structures that emerge bright green and mature to brown.
Callirhytis pigra
oak midrib gall
A cynipid gall wasp that induces distinctive galls on oak leaves. The species exhibits the typical complex life cycle of oak gall wasps, with alternating sexual and asexual generations that produce different gall morphologies on different oak tissues. The common name refers to the gall's position along the leaf midrib.