450 U. S. NATIONAL MUSEUM BULLETIN 2 1 6 part 3 



coxae are often marked with fuscous, and front and middle coxae have 

 the white markings averaging larger and more sharply defined. 



Type: 9, in Sonoran desert just north of Roosevelt Lake, Ai*iz., 

 Apr. 21, 1947, H. and M. Townes (Washington, USNM 63829). 



Paratypes (15 cf, 169): From Alberta (Lethbridge) ; Ai'izona 

 (Phoenix and near Roosevelt Lake); California (Bigpine Creek in 

 Inyo Co. at 6,000 ft., and Fan Hill Canyon 10 miles northeast of 

 Thousand Palms); Colorado (Inspiration Point near Denver, Lyons, 

 Morrison, and White Rocks near Valmont) ; Montana (Marias River 

 20 miles south of Chester) ; North Carolina (Southern Pines) ; Texas 

 (Dallas and 6 miles west of "Gov. Springs" in Big Bend National 

 Park); and Mexico (Aguascalientes and Teotihuacan Pyramids). 



Dates of collection are from late spring to mid-summer. The 

 earliest and latest records are: April 6 at Dallas, Tex., and in Fan 

 Plill Canyon, 10 miles northeast of Thousand Palms, Calif.; April 21 

 near Roosevelt Lake, Ariz.; April 30 at White Rocks, near Valmont, 

 Colo.; July 6 at Lethbridge, Alta. ; July 6 and 7 at Teotihuacan 

 Pyramids, Mexico; and July 16 at "Gov. Springs" in Big Bend 

 National Park, Tex. 



There is one reared specimen: 9, bred from cocoon in cactus stem, 

 Aguascalientes, Mexico, December 3, 1909, E. A. Schwartz. 



This species ranges through the drier, warmer areas of the United 

 States, and southwestern Canada, and is found in Mexico. It has 

 a spotty distribution which seems to be correlated with that of cactus 

 (Opuntia spp.). 



8. Mesostenus thoracicus Cresson 



Mesostenus thoracicus Cresson, 1864, Proc. Ent. Soc. Philadelphia, vol. 3, p. 314; 



cf, ?. Lectotype: ?, Delaware (Philadelphia), 

 Mesostenus erythrogaster Ashmead, 1890, Proc. U.S. Nat. Mus., vol. 12, p. 406; 



cf . Type: cf, Wisconsin (Washington). 



Front wing 5.5 to 8.5 mm. long; clypeus of moderate size, rather 

 strongly convex, its apical edge rather wealdy arcuate; thorax shorter 

 and stouter than in any other species of the genus except melanurus; 

 temple w^eakly convex; prepectal carina strong and sharp to upper 0.4 

 of hind margin of pronotum; punctures on mesopleurum moderately 

 coarse, strong, those on its median part separated by about 0.25 their 

 diameter, elsewhere a little sparser; apical propodeal carina of male 

 strong, sharp, and complete, sublaterally elevated to form a weak crest; 

 apical propodeal carina of female broadly interrupted medially, sub- 

 laterally elevated as a strong crest, the crest less oblique than in other 

 species of the genus; areolet about 1.4 as wide as high; second tergite 

 of female wealdy mat, with medium-sized punctures that are separated 

 by about 0.75 their diameter; ovipositor sheath about 0.60 as long as 



