Contarinia negundifolia

The gall, caused by several larvae, develops by extensive hypertrophy of the leaf tissues; it is an irregular, elongate, globose swelling along the midrib or along the larger lateral veins of the leaflet. The size varies considerably, depending largely on the number of larvae within, and galls on lateral veins are often smaller than those on the midrib. Usually only one gall forms on a leaflet.

A young gall is green with bright crimson areas, and a mature one is mostly green. Degenerating ones become yellow, then turn brown. Galled leaves degenerate and fall from the tree shortly after larval departure. The mature gall is turgid; the degenerate one is flaccid and rubbery.

Felt described the gall and stated that the opening is on the under-surface of the leaf. Actually, the gall develops while the leaf is still partly closed so that at maturity the opening is a narrow slit formed by that portion of the upper leaf surface at the edge of the gall.

Contarinia negundifolia (Felt)

Hosts: Boxelder

This gall is an elongated, succulent, rolled swelling of the leaf on both sides of the midrib.
Color: green

Cecidomyia negundinis, n. sp.

Galls. — The galls are produced from terminal buds on all parts of the tree, and each is made up of a number of transformed leaves and petioles, arranged in pairs opposite each other, in which the two leaves are opposite. They are sub-globular in outline and vary from less than one-half of an inch to nearly an inch in diameter. The outer basal portion of the gall is formed by an enormous enlargement of the bases of the petioles of two leaves which unite and form a receptacle like the cup of an acorn, holding the inner portions of the gall. In the central part of the gall the leaf blades may be entirely involved or their tips may be expanded.

Contarinia negundifolia Felt (Boxelder gall midge)

Eight ( 4 percent ) of the boxelder areas examined had the boxelder gall midge in 1960; all were in North Dakota. The infestation level, rated by the quantity of galls on each tree, ranged from trace to light. Most areas were shelterbelts, but two natural stands had the insects. An insect, probably this species, was reared from galls on boxelder leaves at Ames, la., prior to 1900. According to Felt ( 1908 ) the infestation was considered "quite serious to boxelder." It was not explained whether this referred to actual injury to the tree or whether the galls were just numerous. The latter is suspected. Damage by this insect probably results from premature leaf fall.

Cecidomyia negundinis

This is a very minute, two-winged fly which lays eggs on the leaves of the box-elder. As a result the leaves form unsightly galls which interfere with the proper functioning of the foliage. Tiny maggots are found inside of the galls.

Cecidomyia negundinis

Acer negundo

Swellings on the midrib of the leaflets of the Box Elder, much resembling Cecidomyia pellex on the White Ash. The swellings form two long circular chambers, one on either side of the midrib, opening on the upper surface by slits running the whole length of the gall. Occurs on Box Elder (Acer negundo). Not common.

Itonida negundinis (Felt), the boxelder gall midge, produces terminal bud galls with a diameter of 1 to 2 cm. or long fleshy galls along the midrib of the leaf. The species is reported to have caused serious injury at Ames, Iowa.

Acer negundo