Ulmus
Guides
Aceria campestricola
Elm Leaf Gall Mite
Aceria campestricola is a gall-forming eriophyid mite that induces small pouch-like galls on elm leaves. First described in 1865, this microscopic arachnid overwinters in bark crevices before emerging in spring to attack new foliage. The species exhibits complex taxonomic history with related forms previously described under separate names based on gall morphology.
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.
Agromyza aristata
elm agromyzid leafminer
Agromyza aristata is a leaf-mining fly in the family Agromyzidae, commonly known as the elm agromyzid leafminer. The species creates serpentine leaf mines in elm leaves and shows a strong preference for American elm (Ulmus americana) over Asian elms and hybrids. It is widespread throughout eastern North America and has been documented as a pest in urban landscape settings.
Aproceros
Aproceros is a genus of sawflies in the family Argidae, comprising ten recognized species native to eastern Asia. The genus gained international attention following the introduction of Aproceros leucopoda (elm zigzag sawfly) to Europe around 2003 and subsequently to North America in 2020. This invasive species has demonstrated rapid range expansion and significant defoliation capacity on elm trees (Ulmus spp.). Most Aproceros species remain restricted to their native East Asian ranges, with limited biological information available for the genus beyond A. leucopoda.
Aproceros leucopoda
elm zigzag sawfly
Aproceros leucopoda, commonly known as the elm zigzag sawfly, is a small sawfly native to eastern Asia (China and Japan) that has become an invasive pest in Europe since 2003 and North America since 2020. The species derives its common name from the distinctive zigzag-shaped feeding pattern created by young larvae on elm leaves. Populations are entirely female and reproduce through thelytokous parthenogenesis, enabling rapid establishment from single individuals. The species can cause severe defoliation of elm trees and has recently been documented feeding on Japanese zelkova.
Eriosomatini
Eriosomatini is a tribe of gall-forming aphids in the subfamily Eriosomatinae, comprising approximately 140 species across 16 genera. All members induce galls on host plants in the family Ulmaceae, primarily on Ulmus (elms) and Zelkova species. The tribe exhibits complex life cycles with alternation between primary and secondary hosts, though some species have reduced or lost host alternation. Molecular studies have demonstrated that DNA sequencing can reliably associate morphologically distinct life stages to species, addressing a major identification challenge in the group.
Fenusa ulmi
elm leafminer
Fenusa ulmi is a sawfly in the family Tenthredinidae whose larvae mine leaves of elm trees (Ulmus spp.). Native to Europe, it has been introduced to North America where it functions as a pest of ornamental and nursery elms. The species shows strong host specificity, with European elm taxa being most susceptible to damage. Adult emergence and oviposition are tightly synchronized with host leafing phenology, enabling degree-day modeling for monitoring and prediction.
Hylurgopinus rufipes
Native Elm Bark Beetle
The native elm bark beetle is a small scolytine weevil and principal vector of Dutch elm disease in the northern Great Plains and prairie provinces of Canada. Adults are brownish-red, measuring 2.3–2.9 mm, and complete one generation annually. Overwintered adults emerge in spring to colonize weakened or dying American elm, constructing egg galleries in the inner bark where larvae feed on cambium tissue. The species exhibits distinctive acoustic communication: males produce simple multipulse calls, stress/rivalry chirps, and bimodal premating stridulation at gallery sites, while females do not stridulate. Males become strongly arrested at attractive female galleries and engage in brief contests with rival males shortly after a resident male establishes presence.
Magdalis armicollis
Red Elm Bark Weevil
Magdalis armicollis is a bark weevil in the family Curculionidae, commonly known as the red elm bark weevil. The species is strongly associated with elm trees (Ulmus), with larvae developing within wood and adults feeding on foliage. It occurs across eastern and central North America. The common name refers to its association with red elm (Ulmus rubra).
Orchestes
flea weevils
Orchestes is a genus of flea weevils (Curculionidae) comprising six species in North America and additional species in Eurasia. Members are small beetles (2–4 mm) associated with woody host plants, particularly trees in Ulmaceae and Fagaceae. The genus was historically confused with Rhynchaenus, from which it has been redefined. Several species are significant pests: O. steppensis is a destructive invasive of elms in China and North America, O. alni (European elm flea weevil) damages elms in Europe and North America, and O. fagi attacks beech trees. Larval habits vary—most are leaf miners, though O. hustachei uniquely parasitizes aphid galls.
Phyllonorycter occitanica
Phyllonorycter occitanica is a micro-moth in the family Gracillariidae, known from Texas, United States. The larvae are leaf miners that feed on elm species (Ulmus), specifically Ulmus fulva and Ulmus rubra. Like other members of its genus, it produces characteristic blotch mines on the leaves of its host plants. The species was described by Frey and Boll in 1876.
Scaphoideus luteolus
White-banded Elm Leafhopper
Scaphoideus luteolus is a phloem sap-feeding leafhopper native to the eastern United States and the only confirmed vector of Candidatus Phytoplasma ulmi (CPu), the causative agent of elm phytoplasma disease. The species does not cause direct damage through feeding but transmits this pathogen to elm trees (Ulmus spp.), resulting in heavy damage to North American elm populations. It has three developmental stages—egg, nymph, and adult—with overwintering occurring in the egg stage. Both nymphs and adults can acquire and transmit CPu and remain infective for life.
Xanthogaleruca luteola
elm leaf beetle
Xanthogaleruca luteola, the elm leaf beetle, is an invasive leaf beetle native to Europe that has become the most serious defoliator of elm trees in North America. Adults are yellow to olive-green with distinctive black lateral stripes and spots. Both adults and larvae feed on elm foliage, with larvae skeletonizing leaves by consuming soft tissue between veins. The species has multiple generations annually, with larvae overwintering in soil or bark crevices. Biological control using introduced parasitoids has reduced its pest status in many regions.