ICHNEUMON-FLIES, PART 2: XORIDINAE 539 



it is yellow; propleurum yellow, often margined with black; pronotum 

 yellow, its lower margin black, its groove fulvous or black; prepectus 

 black; mesosternum and mesopleurum yellow, the mesopleurum with 

 a broad longitudinal fulvous stripe that is often more or less replaced 

 with black; mesepimeron yellow; mesoscutum fulvous, its lateral edges 

 black and position of notauli marked with yellow; scutellum and post- 

 scutellum yellow, with adjacent black areas; metapleurum yellow, 

 fulvous medially or sometimes mostly fulvous; metasternum black; 

 propodeum fulvous, yellow apically and basolaterally, black on base, 

 on basal area, and adjacent to lateral longitudinal carina; front and 

 middle legs mostly yellow; hind legs mostly f ulvous ; first tergite brown, 

 yellow laterally, the rest of abdomen brownish fulvous, paler laterally. 



The relative extent of yellow, fulvous, and black markings is vari- 

 able, but usually stays within the limits described. 



The parasitic habits of this species have been described by 

 Graenicher and Rau (see references above). It attacks the nests of 

 bees of the genus Ceratina, which construct their cells, one cell above 

 the other, in the hollowed-out twigs of shrubs and brambles with large 

 pithy centers. The parasite egg is laid on or near the egg of the bee 

 in one of the cells. The hatching parasite larva eats the bee egg or 

 young larva, whichever may be present, next the bee bread, and then 

 invades one or more adjacent cells and eats the bee larvae in them. 

 It pupates in the twig and emerges early the following summer. 



Specimens (19 d\ 829): From Arizona (10 miles west of Jacob Lake, 

 Oak Creek Canyon, and Parker Creek in the Sierra Ancha) ; Colorado 

 (Boulder and near Estes Park); Connecticut (Hartford); Iowa (Sioux 

 City); Maine (Monmouth); Marjdand (Beltsville, Glen Echo, Laurel, 

 Plummers Island, and Takoma Park); Massachusetts (Arlington, 

 Holliston, and Martha's Vineyard) ; Michigan (Ann Arbor, Cheboygan 

 Co., Cooper in Oakland Co., Midland Co., Owosso, and Van Buren 

 Co.); Missouri (St. Louis); New Jersey (Moorestown and Westfield); 

 New York (Arnot Forest in Tompkins Co., Buffalo, Flatbush, Harts- 

 dale, Heathcote, "Indian Ladder," Ithaca, Lockport, New Baltimore, 

 Nyack, Sea Cliff, West Farms in New York City, and Yonkers) ; North 

 Carolina (North Fork of the Swannanoa River in the Black Mts. 

 and Wake Co.); Ohio (Put-in-Bay) ; Ontario (Cornwall, Niagara Glen, 

 Ottawa, Point Pelee, and Simcoe); Penns3dvania (Allegheny Co., 

 Dauphin, Ingram, Perdix in Dauphin Co., Perrysville, and Stoverdale 

 in Dauphin Co.); Quebec (Wakefield); South Carolina (Greenville); 

 Tennessee (Knoxville); Texas (Brownsville and Calvert); Virginia 

 (Arlington, Chain Bridge near McLean, Dayton, Falls Church, and 

 Vienna); West Virginia (Cheat Mt. at 2,000 ft. in Randolph Co.); 

 Wisconsin (Madison); and Mexico (15 km. east of Sombrerete in 

 Zacatecas, and "Teotihuacan Pys. Mex."). 



