THE SAWFLIES OF BOULDER COUNTY, COLORADO 103 



four posterior tarsi brownish; wings hyaline, iridescent; venation dark brown, costa 

 and stigma pallid. Female: Sheath broad at the base, sharply acuminate at tips and 

 emarginate beneath; black color at the base of the abdomen only. 

 Male; Boulder, Colorado, August 11, 1911 (S. A. Rohwer). 



Genus PTERONIDEA Rohwer 



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

 tarsal claws cleft; pentagonal area present; head and thorax shining; posterior tibiae 

 simple; sheath rather narrow; labrum but slightly projecting. 



The larvae of the species belonging to this genus are external feeders on various 

 plants, but as a rule they prefer species of Salix. They are often gregarious although 

 certain species are solitary. 



(21) P. arapahonum (Cockerell). Female: Length 6 mm. Black; mouth, 

 angles of pronotum, spot on the mesoepisternum, scutellum, metanotum, abdomen, legs 

 and antennae beneath rufous or reddish-yellow; wings hyaline, iridescent, venation 

 black. This is probably the same as ribesii, but the European form will have to be more 

 closely studied before a conclusion is reached. 



Boulder, Colorado. Early in April (T. D. A. Cockerell, W. P. Cockerell, S. A. 

 Rohwer). (Type locality.) 



(22) P. cockerelli (Rohwer). Most of head, antennae, scutellum, abdomen, 

 except sheath, hind tibiae, except apex, reddish-yellow; margin of pronotum, four anterior 

 legs (femora reddish apically), hind coxae, trochanters, base of hind femora pallid; 

 wings hyaline; venation dark brown. 



Campus of University of Colorado, August (T. D. A. Cockerell). (Type locality.) 



(23) P. ventralis (Say). Length 7 mm. Black; mouth-parts, orbits, pronotum, 

 venter, coxae trochanters, most of tibiae, and anterior femora beneath pallid; wings 

 hyaline, venation black. 



Boulder, Colorado. Female, August n, 1911 (S. A. Rohwer). New to Colorado. 



Bibliography 

 Chittenden, F. H. "The Rose Slugs. " Circ. 105 U.S. Dept.Agric. Bur. Ent., pp. 1-12, 



1908. [Gives descriptions and figures of adults, work and larvae of three sawflies 



injurious to roses.] 

 Cockerell, T. D. A. "A new sawfly of the genus Xyela. " Can. Ent., Vol. XXXIV, 



pp. 194-195, 1902- 



. "A new sawfly." Ent. News, Vol. XVII, p. 220, 1906. 



. "A new sawfly of the genus Xyela." Can. Ent., Vol. XXXLX, p. 324, 1907. 



Cresson, E. T. "Catalogue of the described species of Tenthredinidae and Uroceridae 



inhabiting North America." Proc. Ent. Soc. Phil., Vol. I, pp. 33-39, 1861. 

 . "List of Hymenoptera collected by J. Ducan Putnam, of Davenport, Iowa, 



with descriptions of two new species." Proc. Davenport Ac. Nat. Sc, Vol. I, 



pp. 206-211, 1876. [Records one species from Boulder County.] 

 . " Catalogue of the Tenthredinidae and Uroceridae of North America." Tran. 



Amer. Ent. Soc, Vol. VIII, pp. 53-68, 1880. 

 . "Descriptions of new North American Hymenoptera — Tenthredinidae and 



Uroceridae." Tran. Amer. Ent. Soc, Vol. VIII, pp. 1-52, 1880. 



