84 BULLETIN 85, UNITED STATES NATIONAL MUSEUM. 



Triosa rotundipennis is merely a variant of this abundant species 

 and not specifically distinct. Although the description of this 

 species appeared before that of albifrons, the latter preceded it in 

 the preUminary sjmopsis and therefore has priority in the name. 



Both this species and quadripundata are exceedingly closely related 

 to the European species urticse, hkewise abundant on nettles. Indeed, 

 it was only after very close comparison that albifrons was not merged 

 into urticx. The principal difference lies in the male forceps; in 

 urticse they are constricted midway, broadened distally and terminate 

 in a conspicuous hook-like process, while in albifrons they are not 

 constricted midway nor broadened distaUy and terminate in a 

 black, subacute tip; they are distinctly shorter and stouter also in 

 albifrons. 



T. quadripunctata is usually easily distinguished from albifrons 

 by the wing markings, but sometimes these maculae are less promi- 

 nent. It is possible that careful life-history studies will show these 

 two American species to be variants of one species. They are 

 apparently often found closely associated in their habitats. 



Nympli. — From 1 to 2 mm in length, according to age, ovate in 

 shape, flat; color: Pale greenish yellow in youngest forms, brown 

 to dark brown in older nymphs; latter with a median dorsal white 

 stripe over entire length, with a fringe of spine-like processes from 

 entire margin and a double row of eight spines on dorsal white stripe. 

 Present in large numbers, singly, on both surfaces of the leaves of 

 Urtica Jioloserecia without flocculence; move about readily and 

 freely. Eggs, nymphs and adults found together in February to 

 April at Stanford University and Nordhoff, California. Adults 

 probably winter over and lay eggs in the early spring. There seem 

 to be several continuous generations. 



The eggs are deposited on the under side of the leaves in great 

 numbers; they are whitish, pyriform in shape, with the large end 

 attached to the leaf, and the other end terminating in an acute point; 

 they stand erect or nearly so. 



TRIOZA FRONTALIS Crawford. 



Figs. 184, 342, 355, 358. 359, 362, 513, 518. 



Trioza frontalis Crawford '10a: 230; '10b: 353; '11a: 426. 



Trioza similis Crawford '10b: 352. 



Trioza similis fovealis Crawford '11a: 438. 



Length of body 2 mm.; length of forewing 2.9 to 3.2; width of 

 head 0.65. General color brownish red, abdomen brownish; genal 

 cones and antennae usually black, at least apically. 



Head narrower than thorax, deflexed; vertex a httle more than 

 half as long as broad, somewhat bulging in front, with a fovea! 

 impression (often deep) on each side of median line; genal cones 



