also applied to the vein swelling gall; the usage for the bead gall is apparently erroneous

Contarinia negundifolia

Cecidomyiidae

Contarinia

Acer negundo

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Key to shelterbelt insects in the northern great plains

Contarinia a-negundo-bead-gall

Contarinia negundifolia [this specific name is now listed as a synonym of Contarinia negundinis, but the gall Felt describes here matches this leaf gall]

Acer negundo

Variable, subglobose leaf gall, diameter about 2 mm.

Key to American Insect Galls

Contarinia negundifolia Felt
1908 Felt, E. P. N. Y. State Mus. Bul. 124, p. 394
1909 Ent. Soc. Ont. 39th Rep't, p. 43

The species, received through the courtesy of the United States National Museum, was reared April 21, 1885 from leaves of box elder, Negundo aceroides, collected by Theodore Pergande May 12, 1884 in Virginia. Mr Pergande states that the larvae deserted the gall May 15th and entered the ground, remaining there until the following spring. Apparently the same form was received June 20, 1908 from the late Dr James Fletcher, Ottawa, Can., and again July 8, 1916 from Winnipeg, Manitoba, through J. M. Swaine, assistant entomologist of the entomological branch of the Canadian Department of Agriculture. It may possibly be identical with Cecidomyia negundinis Gill.

Gall. Irregular, globose, pocket-shaped, separate or confluent, midrib or vein swellings, usually with a slight enlargement on the lower surface and a marked elevation on the upper surface. The color may vary from a light bluish green to a yellowish or even deep red ; diameter 2 to 4 mm, the opening on the under surface. Badly infested leaves may be crumpled and yellowish.

71st Report of the State Entomologist on injurious and other insects of the state of New York

Contarinia negundifolia [consistent with Felt's usage of this name, but the same source lists D communis as the midge responsible for the boxelder vein swelling gall elsewhere referred to as C negundifolia]

Hemispherical galls on midvein (fig. 66), light green with bluish tint. Boxelder. June to September. Contarinia negundifolia Felt boxelder leafgall

Contarinia sp.

Host: Acer negundo

Globular pouch gall along veins
These reddish, inconspicuous galls appear in June on the upper side of fully expanded leaflets and result from an inpocketing of the leaflet. Each gall contains a single larva.

Range: MD

The plant-feeding gall midges of North America

Irregular bead galls alone or in scattered groups of 2-4 along the midrib (occasionally other veins) on the upper side of Acer negundo leaves. They typically appear gray due to a thick glaucous coating but are green darkening to purplish-red beneath. 

Observations are collected in [this page on BugGuide](https://bugguide.net/node/view/530352).

Three midge galls have been described on Acer negundo: a club-like bud gall, a succulent leaf vein swelling, and a small bead on the upper leaf. 
According to Gagne 1989, Contarinia negundinis is considered responsible for two distinct gall symptoms on Acer negundo. On leaves, it causes succulent pouches along the midrib, sometimes affecting the entire leaf. On stems, it causes the growing tip and the petioles of attached leaves to swell and harden below the bud. The bead gall is considered [an undescribed species](https://bugguide.net/node/view/530352). However, usage in the literature does not uniformly align with this practice.

Gillette gave the name Contarinia negundinis to the bud gall in 1887. Felt reared a midge from a leaf gall (no description given) and named it C negundifolia as early as 1905 (though the species isn't considered formally described until 1908), speculating that it might be a synonym of C negundinis. In 1906, Jarvis attributed the vein gall to C negundinis. Felt's 1917 Key attributes both the bud and vein galls to C negundinis and a gall that seems to match the bead gall to C negundifolia. His 1917 description of C negundifolia is ambiguous but also seems to best match the bead gall. 

All later sources use either C negundinis and C negundifolia to refer to the vein gall or sometimes both the vein and bud galls. Only one source (Stein and Kennedy 1972) mentions the bead gall at all after Felt 1917, and they call it C negundifolia. However, this source also incorrectly calls the vein gall Dasineura communis, so its nomenclature may not be reliable. 

At some point between 1993 and 2010, C negundifolia was officially made a junior synonym of C negundinis. While it would be most convenient to think that C negundinis and C negundifolia always referred to distinct galls that were combined by this synonymy, this doesn't seem to be the case. Without seeing the source in which the two species were made synonymous, it isn't clear which galls are actually included in the synonymy. 

Gallformers ID Notes