102 UNIVERSITY OF COLORADO STUDIES 



The species belonging to this genus make galls on the stems of willows. The gall of 

 an unknown species occurs on an undetermined willow in one of the gulches in front of 

 the "flatirons" at Boulder. This gall is similar to that of Euura cooperae Cockerell. 

 The larvae usually live in the gall and may easily be bred by bringing the gall into the 

 laboratory before activity commences in the spring. 



(17) E. macgillivrayi (Rohwer). Female: Length 6 mm. Almost entirely bright 

 reddish-yellow; basal two thirds of the antennae, small spot about the ocelli spots on the 

 mesonotum, and metanotum black. Male: Length 5.5 mm. Black; head below the 

 antennae, posterior and superior orbits, pronotum, tegulae, venter, legs (except coxae), 

 rufo-ferruginous. Gall: on Salix luteosericea Rydb.; a gradual enlargement of the twig 

 about 30 mm. long. Larva: last stage, 5 mm. long, creamy white, head dark. 



Boulder, Colorado, at the mouth of Boulder Canyon. Adults appearing early in 

 May in the field, earlier in the laboratory (S. A. Rohwer). (Type locality.) 



(18) E. bebbianae (Rohwer). Female: Length 6 mm. Mostly black; apical 

 margin of the clypeus pale; ocellar basin present; frontal crest broken; apex of abdomen 

 pale; orbits pale; stigma black, except extreme base. Male: Length 5 mm. Black; 

 clypeus pale; legs below coxae reddish-yellow; stigma all dark; antennal foveae small; 

 lateral ocellar furrows poorly denned. Gall: an abrupt laternal swelling on twigs of 

 Salix bebbiana. Larva: About 5 mm. long (in last stage); creamy white, head dark. 



Boulder, Colorado. Many males and females bred on galls on Salix bebbiana col- 

 lected near the mouth of Boulder Canyon (S. A. Rohwer). (Type locality.) 



Genus PONTANIA Costa 



Transverse radius wanting; second transverse cubitus present; clypeus emarginate; 

 tarsal claws cleft; posterior tibiae simple; apex of the eighth dorsal segment of male with 

 a small blunt projection; small, 2 to 5 mm.; sheath rather narrow, pointed; usually 

 gall inhabiters. 



The larvae of this genus usually make galls on leaves of species of Salix, although 

 there are a few species which are leaf rollers on Populus. Various galls have been noticed 

 in the county, but only two adults are known. The galls are often pinkish in color, of 

 various shape, and are easily seen near the close of the summer. The larvae, as a rule, 

 leave the galls and pupate in the ground, although a few of them use old galls, or even 

 enter decaying wood. During August galls of an unknown species may be found along 

 the small creek at the head of Pine street, Boulder. 



(19) P. leucostoma Rohwer. Male: Length 5 mm. Black; face below antennae 

 (except supraclypeal foveae), clypeus, labrum, mandibles (except piceous tips), angles of 

 pronotum, tegulae and apex of anterior coxae white; orbits, four posterior coxae, tro- 

 chanters, intermediate femora (except a line above), intermediate tibiae and hind femora 

 (except above and below), hind tibiae (except apex and venter), reddish-yellow; wings 

 dusky hyaline. 



Boulder, Colorado, May 22, 1907, on foliage of Populus angustijolia (S. A. Rohwer). 

 (Type locality.) 



(20) P. nevadensis (Cresson). Male: Antennae as long as the body of the insect; 

 claws coarsely notched; middle fovea elongate; ocellar basin well defined, triangular in 

 outline; reddish-yellow; a large spot on the head, thorax and abdomen above black; 



