108 IOWA ACADEMY OF SCIENCES. 



A NEW CECIDOMID INFESTING BOX-ELDER [Negundo aceroides.) 



BY C. P. GILLETTE. 



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 por- 

 tions of the gall. In the central part of the gall the leaf blades may be 

 entirely involved or their tips may be expanded. 



Oall Flies. — Females, dry specimens. Eyeslavge, coal black and coarsely 

 granulated. Antcnncv, one half the length of the insect, 13 jointed, first joint 

 globular, remaining joints cylindrical; second and third joints contracted 

 in the middle; pedicels of joints, short, about one-fourth the length of the 

 joints; all of the joints moderately set with hairs, the longest of which 

 nearly equal the joints in length. Thorax, very dai'k brown, opaque, and 

 naked, except two rows of long gray hairs in longitudinal grooves, running 

 from collar to scutellum, and similar hairs at the sides of the thorax; scutel- 

 lum of the same color as the meso-thoi'ax, and with a few long gray hairs. 

 Beneath the wings it is yellowish. Dorstirn, dark brown; sides of abdomen 

 and venter, light yellow; abdomen sparsely set with gi'ay hairs above and 

 below. Ovipositor, yellowish brown, and in specimens taken while oviposit- 

 ing, it is exserted one and one-half times the length of the insect. Legs, 

 rather pale; tibitv and tarsi infuscate, rather densely set with silvery hairs. 

 Wings, beautifully irridescent, and rather sparsely set with long gray pubes- 

 cence, fringed all the way around; costal and first longitudinal nervures, 

 rather heavy, and united at the apex of the wing as one continuous vein; 

 the little cross vein between the first and second transverse nervures and the 

 outer or upper branch of the fork in thethii'd transverse nervure are almost 

 obsolete and scarcely visible, except in favorable light. Length of dry speci- 

 mens, one and one-half mm.; length of fresh specimens, two mm. 



The eggs are of a bright orange color, four mm. in length, and much 

 elongated; some are straight, others are variously bent, and all are pointed 

 at one end, and usually with a short pedicel attached. 



