Mar., 1913.] 
Life-Histories of Syrphidae V. 
89 
pupal body becomes separated. The position of the seven pairs 
of pro-legs and of the anal opening are shown as scars on the 
puparium (Fig. 145, e, d). 
The color of the puparium with the pupa enclosed is a very 
dark brown. When empty and dried it is brittle, and a very pale 
ashy-brown in color. The larval wrinkling remains visible to a 
slight extent. 
Pupae of this species were found in abundance at the sewage 
disposal plant the middle of September. The walls of the vats 
are of cement and are, much of the time, six or eight feet higher 
than the level of the water. They are surmounted by an iron 
railing. In the angles of this railing, or on the sides of the wall, 
wherever a crevice or angularity presents itself, numbers of 
puparia were found massed together and considerably over¬ 
grown with webs of spiders. During the winter the empty puparia 
in these locations form excellent nests for the spiders. 
Buckton, writing about E. tenax, states that the larvae buried 
themselves in soft mud, each forming a small dome over itself, 
and so pupating under a shallow covering of mud. This method 
of pupation would be a protection against drought. The pupae 
taken about the middle of September emerged as adults Septem¬ 
ber 26, so that the duration in this stage was at least ten days to 
two weeks. During the winter all the puparia that could be found 
were empty or contained dead nymphs. Does the fly pass the 
winter in some other stage, or can it be that the puparia left 
exposed cannot winter and that normally they bury themselves 
in mud? If the latter is true, other puparia at this place may crawl 
farther and bury in the soil. 
Adult. 
Description slightly modified after Williston, Synopsis N. A. 
Syrph. pp. 161, 162.: 
“Male and female: Length 8 to 10.5 mm. Dark metallic 
green, wholly shining. Thorax sometimes with a bluish reflection. 
Eyes brownish, spotted with small round dots of darker (Plate 
IV, Fig. 150). [This character sometimes disappears after death]. 
The eyes are nearly bare, very slightly pilose near the top. Face 
and front with grayish pile and pollen, a small spot on the tuber¬ 
cle and the cheeks narrowly shining. Antennae brown, dorsal part 
of third joint darker; often the first two joints yellowish; arista 
bare. Thorax and abdomen with obscure yellowish pile. Dorsum 
of the thorax in the female with five grayish-white stripes, the 
middle one slender, linear, the two lateral ones broader (Plate 
IV, Fig. 150). Scutellum with the same dark metallic green. 
Tibiae at the base, sometimes for nearly half their length, light 
yellow; middle, sometimes all the metatarsi, yellowish; the femora, 
except the tip, black; distal portion of tibiae blackish brown. 
Wings hyaline.” 
