166 U. S. NATIONAL MUSEUM BULLETIN 209 



with fine punctures, its pubescence moderately short, whitish, or 

 dusky. 



Black. Head, thorax, and coxae with a dark greenish blue irides- 

 cence; legs beyond coxae and abdomen with a similar but fainter 

 iridescence; lateral 0.3 ± of clypeus and lateral 0.25± of face whitish; 

 palpi and tegula dark brown; wings subhyaline. 



Female: Fore wing 4.5 to 6.8 mm. long; clothing hairs on frons 

 short and rather dark, arising from fine distinctly separated punc- 

 tures on a mat background; apical margin of clypeus broadly angled 

 to a rounded median point; second flagellar segment about 3.8 as 

 long as wide; pronotal groove without distinct cross wrinkles; vena- 

 tion as noted in the key; pygidial area pohshed, without evident 

 punctures. 



Black, with a dark greenish blue iridescence, rather strong on the 

 head and thorax, rather weak on the legs and abdomen; wings sub- 

 hyaline. The iridescence of this species is usually a little darker 

 than in architectus or caerulescens. 



Two other Nearctic species of Auplopus superficially similar to the 

 present species are caerulescens and architectus. Males of the three 

 are easily separated, but females with difiiculty; females of nigrellus 

 can usually be distinguished from those of architectus, but often not 

 from those of caerulescens (see the comparisons in the keys). 



Specimens (113 cf, 779): from Arizona (Oak Creek Canyon); 

 California (Claremont and the Mojave Desert); Colorado (Colorado 

 Springs, Denver, and near Estes Park); Connecticut (Chester and 

 East Hartford); District of Columbia (Washington); Iowa (Sioux 

 City); Kansas (Lawrence and Manhattan); Kentucky (Mammoth 

 Cave); Maryland (Bowie, Cabin John, Glen Echo, Mayo, Plummers 

 Island, and Takoma Park); Michigan (Mackinac Island, Mecosta 

 County, and Montmorency CountjO; Minnesota (Aitkin County, 

 Alexandria, and Pope County); New Jersey (Riverton); New Mexico 

 (Cloudcroft and HighroUs) ; New York (Ithaca and Sea Chff) ; North 

 Carolina (Hamrick and Raleigh); Oregon (Blooming); Pennsylvania 

 (Dupont); Tennessee (La Follette) ; Texas (Del Rio, Eastland County, 

 and Fort Davis); Vermont (Laurel Lake near Jacksonville); Virginia 

 (Arlington, Dunn Loring, Great Falls, and Skyline Drive); and 

 Mexico (20 miles north of Comondu in Baja California). 



Collecting dates are from late spring to early fall, or May 10 to 

 Sept. 15 in most of its range. Some dates of capture outside of this 

 span are: Mar. 20 at Washington, D. C; Apr. 2 at Eastland, Tex.; 

 Apr. 12 at Claremont, Calif.; May 9 at Lawrence, Kans., and in the 

 Mojave Desert, Calif.; Sept. 22 at Cabin John, Md.; Sept. 24 at 

 Manhattan, Kans.; and Oct. 26 and 31 at Takoma Park, Md. Bio- 

 logical data associated with the specimens are: one collection from 

 pitch-pine honeydew; five collections in woods; two collections "on 



