504 PROCEEDINGS OF THE NATIONAL MUSEUM VOL, 118 
Suillia plumata (Loew) 
FIGuRE 8 
Helomyza plumata Loew, 1862a, p. 227 (Centuria 2, 88).—Aldrich and Darlington, 
1908, p. 90. 
Suillia plumata (Loew), Czerny, 1924, p. 37. 
Suillia chaetomera Czerny, 1933, p. 236.—Steyskal, 1944, p.175. New synonymy. 
Most of the specimens of this species which have been collected in 
eastern states have setae on the anterior half of the dorsum of the 
scutellum. Czerny (1933) described as a new species (Suillia chaeto- 
mera) a specimen from California which was similar to S. plumata 
(Loew) except that it lacked setae on the dorsum of the scutellum. 
During the course of the present study I found that the pilosity of 
the scutellum in this group is highly variable. For example, in a 
series of 16 specimens collected on June 21-25 at Ledges State Park, 
Iowa (J. Laffoon), the number of setae on the dorsum of the scutellum 
varies from none to as many as thirty. Eastern specimens in the 
U.S. National Museum show a variation from none to 50. All 
specimens from the western United States have the dorsum of the 
scutellum bare, although they are otherwise indistinguishable from 
the eastern forms. Evidently there are genetic differences among 
these populations, but reproductive isolation is not indicated. Thus 
the presence or absence of setae on the dorsum of the scutellum is not 
sufficient grounds for splitting this group into two species. I have 
therefore synonymized Czerny’s S. chaetomera with S. plumata (Loew). 
I have examined the type (a male) of S. chaetomera Czerny. It is 
a shriveled specimen which was probably not well matured when 
pinned. It is a paler yellow than most specimens. 
MALE AND FEMALE.—Head yellow (often very pale); front, vertex, 
and third antennal segment sometimes reddish; aristae brown, long, 
plumose; 3 or 4 irregular rows of buccal setae; cheek-eye ratio from 
0.42 to 0.50. 
Thorax reddish yellow on mesonotum, paler yellow on pleura; 
scutellum with none to 50 or more setae on dorsum (mostly on anterior 
half), several setae laterally between the bristles; mesopleuron bare, 
sometimes darkened in upper portion; legs yellow, darkened on distal 
tarsal segments; wings clouded with brown along crossveins and the 
ends of the second through the fourth longitudinal veins; abdomen 
yellowish orange with posterior margins darkened, hypopygium 
yellow. 
LrenetH.—4.5-6.5 mm. 
DistriBuTIoN.—British Columbia to Nova Scotia, south to Cali- 
fornia, Kansas, Georgia; May—November. 
