173 
The life history of the insect, so tar as I have been able to trace it, is 
as follows, popularly presented: It hibernates in the perfect state, 
hiding, like the house fly, in cracks and crevices of the buildings 
which it frequents and behind furniture and machinery. The flies 
become active only when warm weather sets in. According to my in- 
formant they are first noticed, in the curing establishments, around 
the vats of “yellow wash” which is composed of glue, rye flour, and 
colormg matter, possibly attracted by the odor of the glue. If not 
rigidly excluded they follow the pieces of canvased and _ yellow- 
washed meat to the storerooms and deposit their eggs upon the wrap- 
pers, preferably among the folds, if they can.find an opening that will 
admit them, otherwise upon spots where the fat has penetrated and 
loosened the wash. It has been difficult to ascertain the exact num- 
ber of eggs laid by a single fly, as they are deposited not only in more 
or less compact clusters of from five to fifteen, but are also scattered 
singly. In the observation jars the average was about thirty, but it is 
possible that in these jars, confined upon small bits of meat and subject to 
much disturbance, the conditions were not normal and the number of 
eggs may, in consequence, have been reduced. Those of an individual 
seemed to be all deposited about the same time, in the course of an 
hour or less, soon after which the insect perishes. The egg is pearly- 
white, slender oblong, slightly curved, 1"™ in length, with a diameter 
about one-fourth the length. Hatching takes place within thirty-six 
hours and, leaving a filmy pellicle behind, the minute, translucent-white 
larva moves with wonderful activity in the direction of the food sup- 
ply. Except in increase in size it does not change much in its charac- 
teristics. It is cylindrical, tapering gradually toward the anterior end, 
and is truncate posteriorly, furnished at this extremity with two horny, 
projecting stigmata and a pair of fleshy filaments. 
There is no variation in the white color except in the retracted mouth- 
hooks which show a shade of dark gray. Dr. Packard, in his Guide, 
quotes from an observation of Prof. Putnam regarding the leaping 
power of the insect— 
When about to leap, the iarva brings the under side of the abdomen toward the 
head while lying on its side, and reaching forward with its head and at the same 
time extending its mouth hooks, grapples by means of them with the hinder edge 
of the truncature and pulling hard, suddenly withdraws them, jerking itself to a 
distance of 4 or 5 inches. 
To my knowledge the distance to which it “skips” is often much 
greater. I think the “skipping” a latent power in the insect as a meat 
pest, as there is no occasion to exercise it by the majority of the individ- 
uals. When breeding in cheese it would be necessary in many cases to 
escape by this means to some place in which it could transform in 
safety, but on the canvased packages of ham and bacon, the folds of 
the wrapper afford the most desirable of hiding places. It completes 
its growth in seven to eight days, attaining a length of from 7 to 9™™ 
