SANBORN : KANSAS APHIDID.K. 23 



lias a waxy coating that gives it a similarity to mercury in 

 action and appearance. The insects also have this pulverulent 

 coating. 



Tetraneura ulmi De G. Plate V, fig 34. 



Head black. Antennae dark and annulated ; length of seg- 

 ments: I, 0.01 ram.; II, 0.03 mm. ; III, 0.16 mm. ; IV, 0.07 

 mm.; V, 0.05 ram.; VI, 0.06 ram., including the unguis; 

 unguis alone, 0.01 mm. ; total length, 0.43 rara. Eyes black 

 and large in proportion to the head ; ocular tubercles present ; 

 ocelli large and of a reddish color. Beak dark, 0.18 rara. long, 

 extending midway between the pro- and mesacox^e. 



Prothorax brownish, short and alraost covered dorsally by the 

 raesathorax. Latter dark; wings pellucid, venation dark. 

 Stigraa, 0.14 rara. wide and 0.45 mm. long. Total wing expan- 

 sion, 4.84 rara. Legs dark, slightly hirsute, and norraal in 

 length. 



Abdoraen yellowish brown. Honey-tubes tuberculate. Style 

 obsolete. Total length of body, 1.99 rara. 



This forra was taken June 26, on the elra {Ulmns americana) . 

 It is gregarious, and lives in what is known as a cockscorab 

 gall. Following is Mr. Burrows's description of the gall : "This 

 species forras a cockscorab-like gall on the upper side of the 

 leaf of the elra (Ubiius americana) in June, on the outer young 

 leaves. The gall is usually about 25 rara. in length and about 

 8 rara. in height, and is very conspicuous, being truly cocks- 

 comb-shaped. Its sides are grooved with perpendicular 

 wrinkles and its surarait toothed. In early suraraer the gall is 

 a light green color, lighter than the leaf, turning red after some 

 exposure to the sun. It dies and becoraes a straw color when 

 the insect eraerges. The gall has an external opening on the 

 under side of the leaf, which is a slit-like orifice. The interior 

 of the gall has wrinkles corresponding to the exterior. These 

 galls are not coraraon in this region, being obtained frora only 

 One small elm tree on the Wakarusa river, July 1. This species 

 attacked only the young trees, as far as could be observed ; the 

 larger trees surrounding this tree had no galls, while this young 

 tree and surrounding sprouts were covered with them. Riley'- 

 says that there are several generations of this gall-producing 



12. Eiley, Bull. U. S. Qeol. Surv , vol. V, p. 9. 



