Celticecis capsularis

The species is primarily identified by its association with the distinctive rosette galls on hackberry (Celtis). The rosette gall structure—tight clusters of shortened, distorted leaves emerging from a single point—distinguishes it from other Celticecis species that produce different gall morphologies. Celticecis spiniformis produces spiny, irregular galls, while Celticecis globosa forms rounded, detachable leaf galls. Adult midges require microscopic examination for definitive identification; the galls provide the most reliable field diagnostic.

Adults are small, delicate flies typical of gall midges, with long, slender legs and reduced wing venation characteristic of the family Cecidomyiidae. The larvae develop within the rosette galls they induce on host plants. The galls themselves appear as clustered, leafy rosette formations—distinct from other hackberry gall types in their compact, bud-like aggregation of distorted leaves and stems.

Associated with hackberry trees (Celtis species) in temperate deciduous forests, woodland edges, riparian corridors, and urban plantings where host trees occur. The presence of suitable host trees is the primary habitat determinant.

Eastern and central North America, following the range of its hackberry host trees. Documented from the Great Plains eastward to the Atlantic coast, and from the Great Lakes region south to the Gulf Coast.

Adult emergence and gall formation occur during the growing season when hackberry leaves are expanding; specific phenology not well documented in available sources. Galls persist on trees through fall and may remain visible in winter.

• Celtis - gall inducerHackberry species; specific host species not definitively documented in available sources

Induces rosette galls by chemical manipulation of hackberry bud or leaf tissue, causing abnormal proliferation of shortened leaves into a compact cluster. Larvae develop within the gall structure, feeding on nutritive tissue the plant produces in response to midge activity.

As a gall inducer, creates microhabitat structures that may be utilized by other organisms. The galls represent a form of plant parasitism that redirects host resources to midge development.

Primarily of interest to entomologists and naturalists studying plant-insect interactions. The galls are conspicuous and may attract attention from observers of hackberry trees, but cause no significant economic or ecological impact. Occasionally noted in urban forestry contexts where hackberries are planted as street trees.

• Celticecis spiniformisAlso induces galls on hackberry, but produces irregular, spiny galls rather than compact rosettes
• Celticecis globosaForms rounded, detachable leaf galls on hackberry, distinct from the sessile rosette structure of C. capsularis
• Pachypsylla speciesPsyllids that induce different gall types on hackberry; galls are typically pouch-like or nipple-shaped rather than rosette-forming

• gall midge
• Cecidomyiidae
• Celtis
• hackberry
• plant gall
• North America

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