Nu.i4,s7, NORTH AMERICAN DIGGER WASPS— FERNALD. 3-45 



scriceou.s; abdomen generally with more dark or black on it than in 

 the female; pubescence generally somewhat more developed. 



Lcruith. — Females, 12-21 mm.; males, S-1-1: mm. 



This species is essentially tropical and subtropical in distribution. 

 First descril)ed from St. Thomas, I have seen specimens from Cor- 

 doba, Argentina; and from Brazil, Cuba, Jamaica, Mexico, Texas, 

 New Mexico, California, Utah, Nevada, Colorado, Arizona, and 

 Montana. Specimens from Florida; Camden Count}, New Jersey; 

 Raleigh, North Carolina, and Georgia, which I have also studied, 

 seem to be intermediate between this species and the next {C. hlfoveo- 

 latmn), agreeing in some characters with the one, and in others with 

 the other, and it has tinally seemed necessary to name them in 

 accordance with the preponderance of these characters. 



Characters separating Chlorlon, thompe, from Chlorion hifoveolaiam. 



For this purpose Kohl gives numerous distinguishing features, 

 particularly relating to comparative measurements of different parts 

 of the body. Tests of these on several hundred specimens have not 

 given satisfactory results as a whole, so many examples agreeing in 

 part with one set and in part with the other. The following characters 

 seem to the writer to be those most useful in separating the species, 

 but only when taken together. The female C. tliornx, has the sculp- 

 turing of the thorax everywhere developed; the ridges from the base 

 of the hind wing to the median segment stigma run nearl}^ horizontal; 

 pu])escence is present on the prothoracic lobe and above the middle 

 and hind coxa3 and is generally quite stronglj^ developed; the wings 

 are more hyaline and the average size of the individuals is larger. 

 The female C. htfoveolatuui ma}^ have the sculpturing of the thorax 

 everywhere developed, but there is a strong tendency for it to be 

 replaced, particularly on the dorsum of the median segment and on 

 the sides of the thorax by a dull, lusterless black, which shows no 

 markings of any kind. The ridges between the base of the hind wing 

 and the stigma of the median segment run more obliquely downward 

 and forward; traces of pubescence may be present where they are in 

 the other species, but they are merely traces; the wings are somewhat 

 more fuliginous everj^where, and the average size is less. 



The males are more readily distinguished. In C. tliomix. the length 

 of the first two segments of the filament taken together is less than 

 that of the third, and the posterior margins of the sixth and seventh 

 ventral abdominal plates, though sometimes slightly emarginate, are 

 never excised, though in one or two cases I have seen specimens in 

 which slight elevations at the sides with a depression in the middle 

 gave a very deceptive appearance to these segments. In C. Infoveola- 

 tiuii the length of the first two segments of the filament taken together 

 exceeds the length of the third, and the posterior margins of the sixth 



