SUBFAMILY POLLENIINAE 351 
cluster fly, that it is a nuisance at times is illustrated by the 
following letters. 
Elmhurst, Il., Feb. 4, 1929——‘‘My house here in Elmhurst 
has been teeming with blowflies all winter. They seem to come 
up through the opening where the window ropes pass through 
and settle in the air-space between the regular windows and the 
storm sashes. They survive even at eighteen degrees below 
zero.’’ Union, Ohio, Sept. 22, 1985.—‘‘This week, cluster flies 
are coming in wholesale numbers. They appeared first in the 
attic where the windows are screened and not a housefly has 
ventured all summer. Next they appeared in a bed-room on the 
second floor—the very same places in which they appeared last 
year, only to continue until no part of the house was free from 
them. It isn’t just a fly or two—or even a half a dozen, but 
anywhere from fifty to a hundred on a window, first between 
the blind and glass, then later out into the room.’’ 
TRIBE MELANODEXIINI 
The species placed in this tribe belong to two genera, and evi- 
dently occur only in the far western part of the United States. 
Little is known of the habits of these species, and nothing is 
known of the immature stages. 
Male and female. Head (pl.-7, D) with palpus filiform or 
slightly clavate at tip; antennal bases conspicuously separated 
by a narrow and high, or wide and low, carina; third antennal 
segment rarely longer than one and one-half times the second 
and not reaching over two-thirds the distance to the vibrissa; 
arista thickened slightly at base, the penultimate segment rather 
bulbous but not longer than its greatest diameter. 
Thorax and abdomen mostly bare or with short, black hair 
but without crinkly hair or pile; propleura bare; notopleural 
bristles two; preintraalar bristle one, the presutural absent; 
presupraalar bristle one; postalar declivity posteriorly with a 
tuft of hair; postalar bristles three; prosternum large, bulging 
anteriorly; posthumeral bristle absent. 
Middle femur with from four to five anterior bristles near 
middle, about four posteroventral bristles in a row toward base; 
hind tibia with from three to five bristles in anterodorsal and 
anteroventral rows. | 
Wing with a minute costal spine, third vein bare; fourth vein 
without apical section or fold, the bend obtuse, the apical cross 
vein sinuate only toward margin; apical cell open or closed to 
