520 PROCEEDINGS OF THE NATIONAL MUSEUM vol. 113 
Aecothea fenestralis (Fallén), Haliday, 1838, p. 187. 
Oecothea fenestralis (Fallén), Westwood, 1840, p. 145.—Loew, 1859, p. 55.— 
Pandellé, 1901, p. 354.—Aldrich and Darlington, 1908, p. 73.—Czerny, 1924, 
p. 90; 1927a, p. 31. 
Leria fenestralis (Fallén), Schiner, 1864, p. 30.—Rondani, 1867, p. 126. 
MALE AND FEMALE.—Front yellowish orange to yellowish brown, 
vertex darker, back of head yellowish below; face and cheeks yellow 
to brownish yellow; antennae reddish brown to dark brown, aristae 
dark brown to black, minutely pubescent; posterior fronto-orbital 
bristle well developed, anterior bristle weak or absent; oral vibrissae 
strong, a single irregular row of long buccal setae; cheeks deeper 
behind than anteriorly. 
Thorax brown to blackish; edges of pleural sclerites, scutellum, 
and humeral calli may be yellowed to varying degrees, dorsocentral 
bristles 1+3; scutellum with many setae on dorsum in addition to 
usual 2 pairs of lateral bristles; prosternal bristles absent; mesopleuron 
with a few setae near the propleural bristle, otherwise bare; sterno- 
pleuron with 1 strong bristle and a few setae anterior to the bristle, 
and longer hairs between the coxae; hypopleuron with minute setae 
below spiracle; pteropleuron bare. 
Legs yellowish brown, becoming darker distally; anterior of middle 
femur with a row of weak bristles along middle near upper edge, and 
a stronger row towards the distal end; middle tibia with at least 2 
strong bristles near the middle along the anterior dorsal region, often 
with another weaker bristle in line proximad to these, and 1 or 2 
more bristles near the middle along the posterodorsal side; middle 
tibia with 2 dorsal preapical bristles and 3 or 4 ventral apical bristles. 
Wings tinged with brown; the crossveins may themselves be 
darkened, but the wing membrane is not distinctly clouded along the 
crossveins. 
Abdomen yellowish brown, becoming yellowish posteriorly. 
LenctTH.—3.5-4.5 mm. 
Distrinution.—British Columbia, Minnesota, Iowa, Illinois, 
New York; January—June. 
BroLtocy.—This species has been reported from birds’ nests by 
Leruth (1939). 
Remarxks.—I have examined a type specimen of Helomyza fusci- 
pennis Meigen and confirmed its synonymy with Aecothea fenestralis 
(Fallén). 
As will be noted below, A. fenestralis (Fallén) and A. specus 
(Aldrich) can be distinguished from each other only by means of the 
male terminalia. The latter has been considered a synonym of the 
former, with the result that practically all the specimens in collec- 
tions have been labelled “fenestralis.” Garrett recognized that there 
