ox WARBLE FLY OR EOT FLY. XI 



la some observations taken by Mr. A. C. C. Martyn, Agricultural 

 College, Aspatria, Cumberland, in 1885, of which he sent me notes, he 

 found that the full-grown maggot squeezed itself out of the warble in 

 the morning, or at some time between six o'clock in the evening and 

 8 a.m. the following day. This point he ascertained in the course of 

 his experiments in rearing the chrysalis ; in these he found tlie 

 maggots leaving the warble stuck fast, or trapped, as the case might 

 be, on bird-lime, or in the little bags fixed for them to drop into, in 

 the morning, but never in the middle of the day. 



In the case of eighteen specimens watched by Mr. Martyn, the 

 chrysalis stage lasted about twenty-five days ; but, to ascertain the 

 effect of cold on rate of development, four chrysalids were put by them- 

 selves at a much lower temperature. These developed into flies 

 (scientifically speaking, the pupfe developed into tbe iraago- state) in 

 an average of thirty-six days (that is, took ten days longer in develop- 

 ment than the others), and the flies were not such fine specimens, not 

 so large or well marked as the others. 



The Ox Warble Fly, or Bot Fly (scientifically, the Hypoderma 

 bovis), is a two-winged fly, upwards of half-an-inch in length, so 

 banded and marked with differently-coloured hair 

 as to be not unlike a Humble Bee. The face is 

 yellowish ; the body between the wings yellowish 

 before and black behind ; and the abdomen usually 

 whitish at the base, black in the middle, and 

 orange at the tip. The head is large ; the wings Fig. 14.— Ox Warble 

 brown ; and the legs black or pitchy, with lighter ^^y- 



feet. There are, however, some slight differences in colouring, and 

 amongst those reared by Mr. Martyn, in the case of five out of the 

 twenty-five, the portion of the abdomen beyond the transverse black 

 band was grey instead of yellow or orange. 



The female fly has an ovipositor, or egg-laying tube, formed of 

 telescope-like joints, and ending not in a point for piercing with, but 

 a trifid extremity beset with small hairs (see p. 4). The egg-laying 

 season is mostly in the warm part of the year, but as the time of 

 presence of the maggots extends (as shown by trade reports of con- 

 dition of hides) from February to September, so also must the exist- 

 ence of Warble Flies, to which these warble-maggots turn, extend 

 to some degree over many months, and the date of egg-laying vary 

 conformably. 



Process of formation of the Wai-hle. 



The early part of this operation, including the minute maggot no 

 thicker than a hair going down to the under part of the hide, and there 

 lying feeding in the little bloody sore which it has caused, has been 

 described, so also has its growth, until (tail uppermost) it lies in the 



