1899] CHEESE AND BACON MAGGOT. 11 



winged, the wings transparent, and the neuration as given in the figure 

 after Dr. E. L. Taschenberg at heading; the legs variable in tint, but 

 more or less of a smutty yellow. 



The maggots, of which such a good supply were sent me in the 

 infested slice of Ham as to give excellent opportunity for observation, 

 were (see figures from life at heading) about a quarter of an inch or 

 somewhat more in length when extended, whitish in colour and 

 cylindrical, tapering to the head extremity, within which the black 

 mouth apparatus was very clearly distinguishable. The tail truncate 

 at the extremity, which (as noticed at p. 8) showed at the upper part 

 two small tubercular spiracles, or breathing pores, of which the con- 

 nection of each with a trachea (or air-tube) was very plainly observable 

 (with a two-inch object-glass) ; these tracheae being traceable through 

 the whole length of the maggot. At the lower edge of the obtusely 

 truncate caudal extremity was a pair of somewhat pointed fleshy 

 processes, and on each side a single smaller blunt process was 

 observable. 



Previous to leaping, the maggot fixed its black head-hooks with 

 great care to some part of the tail extremity (taking an appreciable 

 amount of time to arrange this matter to its satisfaction), lying the 

 while on one side, and forming a circle of about an eighth of an inch 

 across ; but, so far as I could see, it was quite immaterial which part 

 of the truncate end of the tail was laid hold of. Then, suddenly 

 letting go, the maggot " skipped" to a variable distance — it might be 

 of about an inch up to about three inches or more — and the operation 

 was most energetically carried on by the collection of maggots which 

 I had under observation, which dispersed themselves in all directions, 

 falling with an audible noise on the sheet of paper on which I was 

 watching their movements. 



On July 15th, two puparia or chrysalis cases were noticeable. 

 These were cylindrical, but lessening to the head end, and somewhat 

 smaller at the tail, which retained to some degree the spiny processes 

 of its maggot condition. Length, little more than half that of the 

 maggot when quite full grown and quite fully extended ; colour bright 

 chestnut, excepting towards the head extremity, which was rather 

 darker in tint, as also (but to a very slight degree) the tip of the tail. 

 A few of the collection of larvse under observation were still at this 

 time in quite young state. 



On July 18th about thirteen puparia were formed, and there were 

 larvse of various sizes — from somewhat less than the sixteenth of an 

 inch in length up to full growth — in the box with the piece of 

 " skipper "-infested Ham. 



The first specimen of the imago — that is, of the perfect fly of 

 P. casei — was developed from my specimens on July 23rd. 



