Eriophyid
Guides
Acalitus brevitarsus
Alder erineum mite
Acalitus brevitarsus is an eriophyid mite that induces distinctive galls on alder species (Alnus). The mite lives and feeds within erineum—dense mats of hair-like structures—on the lower leaf surface, causing pale, domed swellings on the upper surface. It overwinters in old cones and bark crevices during autumn. The species is known from Europe, ranging from Spain to Russia.
Acalitus ruelliae
Acalitus ruelliae is a species of gall mite in the family Eriophyidae. This microscopic arachnid induces abnormal plant growths (galls) on its host plants. The species epithet indicates an association with plants in the genus Ruellia (Acanthaceae). Like other eriophyid mites, it is highly host-specific.
Aceria aceris
maple gall mite, maple erineum mite
Aceria aceris is a gall-forming eriophyid mite that infests maple species (Acer), producing distinctive erineum galls on leaf surfaces. The mite has a worm-like, elongated body with four legs and annular ridges typical of the superfamily Eriophyoidea. It is one of numerous Aceria species specialized on maple hosts, with populations often associated with specific maple species or varieties.
Aceria elongata
Crimson Erineum Mite
Aceria elongata, commonly known as the crimson erineum mite, is an eriophyid mite that induces distinctive erineum galls on the upper leaf surfaces of sugar maple (Acer saccharum). The galls progress from pale greenish patches to rich red-purple coloration as the season advances. This microscopic, worm-like mite has two alternating generations per year and is known from the eastern coast of the United States and Canada. At high densities, it can cause leaf distortion and premature leaf drop, though damage is generally not severe enough to require control measures.
Aceria erinea
Walnut Blister Mite
Aceria erinea is a gall-forming eriophyid mite that induces characteristic blister-like galls on the leaves of common walnut (Juglans regia). First described by Alfred Nalepa in 1891, this microscopic arachnid is a specialized plant parasite with a highly restricted host range. The mite's feeding activity causes distinctive erineum galls—fuzzy, felt-like patches on leaf surfaces. Like other eriophyid mites, it has a worm-like body with only four legs and undergoes rapid development, completing its life cycle in approximately one to two weeks under favorable conditions.
Aceria fraxini
Ash Bead Gall Mite
Aceria fraxini, commonly known as the ash bead gall mite, is an eriophyid mite that induces distinctive capsule galls on ash trees (Fraxinus spp.). This species exhibits a complex life cycle involving alternation of generations, with an overwintering generation consisting solely of parthenogenetic females (deutogynes) and a summer generation containing both sexes (protogynes and males). The mite is distributed across North America, where it is considered a minor pest of ornamental and native ash species.
Aceria fraxiniflora
ash flower gall mite
Aceria fraxiniflora is a North American gall mite that produces distinctive galls on ash trees, particularly on male flowers. Native to North America, it was first recorded in Europe in southeast Hungary in 2017 and has since spread rapidly across eight Central-Eastern European countries by 2023. The mite appears to be a strict specialist on North American ash species, with no records from native European ashes. Its rapid spread on invasive green ash has raised interest in its potential as a biocontrol agent, though its real impact on host fitness remains unquantified.
Aceria mackiei
Live Oak Erineum Mite
Aceria mackiei, commonly known as the live oak erineum mite, is an abundant eriophyoid mite that induces distinctive leaf-blister galls on several species of live oak. This mite is notable for its unique ability to form galls on oaks belonging to both the black oak group and the intermediate oak group, a trait not shared by other eriophyoid mites. The species is widely distributed across western North America and was previously classified under the genus Eriophyes.
Aceria nyssae
Black Tupelo Gall Mite
Aceria nyssae is an eriophyid gall mite that induces distinctive leaf curl galls on Nyssa sylvatica (black tupelo, sour gum). The mite's feeding activity causes leaf margins to curl inward, forming hollow pockets that shelter the mites and their eggs. This species exemplifies the highly specialized host relationships typical of Eriophyoidea, where individual species are often restricted to a single plant host genus. The galls are most evident on young leaves at branch tips during the growing season. Like other eriophyid mites, A. nyssae is extremely small and difficult to observe directly, with populations typically assessed through gall symptoms rather than mite counts.
Aceria paracalifornica
California Sagebrush Gall Mite
Aceria paracalifornica, commonly known as the California Sagebrush Gall Mite, is a species of eriophyid mite in the family Eriophyidae. As a member of the superfamily Eriophyoidea, it is a worm-like, four-legged mite that parasitizes plants. The genus Aceria includes numerous species that cause distinctive plant deformities including galls, witches' brooms, and leaf distortions. The specific epithet "paracalifornica" suggests a close relationship to or similarity with A. californica, a species associated with California sagebrush (Artemisia californica). Eriophyid mites in this genus are highly host-specific, typically specializing on a single plant species or genus.
Aceria parulmi
Elm Finger Gall Mite
Aceria parulmi is an eriophyid mite species commonly known as the Elm Finger Gall Mite. It is a plant-parasitic mite that induces distinctive gall-like structures on elm leaves. Like other members of the genus Aceria, it has a worm-like, elongated body with four legs and is extremely small, typically less than 0.2 mm in length. The mite is specialized to feed on elm species (Ulmus), causing characteristic finger-shaped galls on leaf surfaces.
Aculops rhois
Poison Ivy Gall Mite, Poison Ivy Leaf Mite
Aculops rhois is an eriophyid mite species found in North America that induces distinctive galls on poison ivy and related plants. The species forms small red pouch galls on the upper leaf surfaces of its hosts, which include Toxicodendron species and some Rhus species such as fragrant sumac. The bright coloration of these galls makes the mite more conspicuous than many related Aculops species, contributing to its relatively frequent reporting despite limited formal study.
Eriophyes betulae
Birch gall mite
Eriophyes betulae is a gall-forming eriophyid mite that induces characteristic galls on birch trees (Betula species). The mite is microscopic, worm-like in body form with only two pairs of legs—diagnostic features of the Eriophyidae family. It has been documented in Denmark and other parts of Europe. Like other eriophyid mites, it feeds on plant tissues and manipulates host growth to create sheltered feeding structures.
Eriophyes cerasicrumena
Black Cherry Leaf Gall Mite
Eriophyes cerasicrumena is a gall mite in the family Eriophyidae that induces distinctive spindle-shaped galls on black cherry (Prunus serotina) leaves. The species was formerly classified under the genus Phytoptus. The galls serve as a food source for caterpillars of the cherry gall azure butterfly (Celastrina serotina), which consume both gall tissue and the mites themselves. The species is documented across eastern North America with over 8,600 observations.
Eriophyes leiosoma
Lime Felt Gall Mite
Eriophyes leiosoma is an eriophyid mite species in the family Eriophyidae. The genus Eriophyes contains species associated with plant galls and deformities, including economically significant pests of fruit crops. Some Eriophyes species, such as E. dimocarpi, are known to cause witches' broom disease in longan (Dimocarpus longan) through toxic saliva that induces curled, malformed shoot growth. E. leiosoma itself has been recorded in Scandinavia (Denmark, Norway, Sweden).
Eriophyes tiliae
lime nail gall mite, bugle gall mite, red nail gall mite
Eriophyes tiliae is a gall-forming eriophyid mite that induces distinctive tubular galls on lime (linden) tree leaves. The mite is less than 0.2 mm long and overwinters in bark crevices and around buds before colonizing foliage in spring. Chemicals released during sap-feeding trigger the formation of hollow, finger-like galls that range from yellow-green to red and reach up to 5 mm in height. The species has three recognized subspecies (liosoma, tiliae, nervalis) distinguished partly by gall positioning relative to leaf veins. Despite gall abundance, the mite appears not to harm host tree health.
Phyllocoptes didelphis
Phyllocoptes didelphis is a minute eriophyid mite in the family Eriophyidae. This species belongs to a genus containing many gall-forming and vagrant plant-feeding mites. The specific epithet 'didelphis' refers to the Virginia opossum (Didelphis virginiana), though the reason for this association is not documented in available sources. Eriophyid mites are among the smallest arthropods and are exclusively associated with plants.
Vasates aceriscrumena
maple spindle-gall mite
An eriophyid mite that induces distinctive fusiform (spindle-shaped) galls on maple leaves in the eastern United States. The microscopic mite is visible only through the galls it produces. Unlike the related maple bladder-gall mite, its galls are elongate rather than rounded. The species causes minimal harm to host trees despite the conspicuous galls.
Vasates quadripedes
Maple Bladdergall Mite, maple bladder-gall mite
Vasates quadripedes is an eriophyid mite known for inducing distinctive bladder-like galls on maple leaves. The species is native to North America and has been introduced to parts of Europe, including Britain where it was first recorded in 2002. It is associated primarily with silver maple, red maple, and sugar maple. The galls it produces are a reliable indicator of its presence and are more readily observed than the microscopic mites themselves.