100 ENTOMOLOGICAL SOCIETY OF ONTARIO. 



on the surface ; nor was the solid fat much damaged. The methods of curing these meats 

 had been so perfect, that even after an exposure of two or three weeks in an open shed 

 to the August heats, upon cutting into the centre of a ham and the thickest part of 

 shoulder they were found to be perfectly sound and sweet. In justice to the "skippers," 

 too, I must say that their work does not induce putresence or ill odors, and although the 

 spectacle of a ham swarming, externally, with the various forms of the insect is the reverse 

 of appetizing, yet a large part of it is still edible, and, the outside removed, would be 

 available for potted meats and similar preparations. But, of course, in the original shape 

 it is absolutely unsaleable ; hence the loss. 



The life history of the insect, so far as I have been able to trace it, is as follows, 

 popularly presented : It hibernates in the perfect state, hiding, like the house tly, 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 

 informant they are drst noticed, in the curing establishments, around the vats of "yellow 

 wash," which is composed of glue, rye flour, and coloring matter, possibly attracted by the 

 odor of the glue. If not rigidly excluded they follow the pieces of canvassed and yellow- 

 washed meat to the storerooms and deposit theii eggs upon the wrappers, preferably 

 anion" the folds, if they can find an opening that will admit them, otherwi>e upon spots 

 where the fat has penetrated and loosened the wash. It has been ditHcult to ascertain 

 the exact number 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 observa- 

 tion 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 individnal 

 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, I""" in 

 len«»th, 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 supply. Except in increase in size, 

 it does not change much in its characteristics. 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 larva briugw the under side of the abdomen towaixl the head while lying on it" 

 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 four or five 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 individuals. 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 atford 

 the most desirable of hiding places. It completes its growth in seven to eight days, attain- 

 ing a length of from 7 to 9""", with a diameter at the posterior end of 1.5""". While feed- 

 ing, if the food supply is sufficient, it does not move about much, entire clusters of larvjB 

 often completing their growth in the same bony crevice in which the mother fly had 

 deposited the eggs. When mature, however, it crawls, pulling itself along, apparently by 

 the mouth hooks, into some fold of the wrapper that is comparatively dry, and from which 

 the fly will easily be able to escape. Here it begins to contract in length and assume a 

 yellowish hue, and the separation of the outer skin from the body can be clearly seen. 

 The former gradually hardens and darkens into a golden brown, oblong segmented shell, 

 4 to 5°'"' in length, and which still retains the larval projections on the posterior end. 

 Within this puparium the larva rests for a time— -I have reasons for believing for thirty- 

 six or forty-eight hours, perhaps longer — unchanged, except for a slight reduction in size. 

 I had occasion to observe the action of one of these larvit; whose case was accidentally 

 iroken. It wriggled and twisted about in the most unsatisfied manner, but seemed to 



