VI WARBLE FLY. 



to be of a pear- or club-sbape, wbite, and partially transparent, and 

 marked across wbat may be called tbe back with sixteen short bands 

 of very minute black or dark grey prickles, placed, for the most part, 

 in alternate very narrow and broader stripes (see fig. 3, p. 5). The 

 young maggot possesses (apparently as an instrument for tearing out 

 food) a pair of crescent-shaped forks or diggers (see fig. 4, p. 5). These 

 are of such excessive minuteness that they are only to be found with 

 difficulty, and I have not as yet found them in any but very young 

 maggots. The apparatus may be described as consisting of a pair of 

 crescent-shaped forks, placed nearly side by side at the extremity of 

 processes somewhat bent apart at the ends by which they are attached 

 to the crescents, and attached by the other ends to the membranes or 

 tissues forming the gullet or internal sac of the maggot. The material 

 is chitinous or horny, and the possession by the embryo (still worm- 

 like) maggot of this apparatus for cutting or tearing is of considerable 

 interest in connection with the first minute track (which shows as 

 being cut or torn) down through the hide to the embryo maggot lying 

 below. 



The power of pressure possessed by the maggots at this period of 

 their life is enormous, from their capacity of inflating themselves with 

 fluid until they are so hard that it is scarcely possible to compress 

 them with the fingers, and likewise from their having (apparently) no 

 power of discharging any of their contents. Thus they form living 

 and growing plugs, quite capable of pressing back the tissues from 

 around them, or from before the small hard tip ; but not subject (so 

 long as they continue inflated) to being themselves compressed. I 

 had opportunities of watching this process of inflation both in the 

 worm-shaped maggots and when they were slightly more advanced in 

 growth to a club or lengthened pear-shape. On placing them in fluid 

 suitable for absorption (as in glycerine and water, in which they would 

 live for as long as eighty hours, or until the spiracles sank completely 

 beneath the surface) they became hard and shiny, and with little trace 

 of the segments which are so clearly marked when the maggots are 

 fully developed ; in fact, they were almost of a glassy smoothness, 

 save for the short bands of minute prickles placed along a portion of 

 the back. 



This power of inflation of the maggot appears to be an important 

 agent in forming what is presently the open passage or warble-hole 

 down to the cell beneath. The various stages of maggot life consist 

 of the passage of the worm-like larva to the under side of the hide, 

 where, at this stage, in the small inflamed patches or swellings (see 

 p. 3) it lies free, that is to say, not enclosed in a cell or thickened 

 tissue, merely in a small bloody sore, in which by the colour of its 

 contents it may be seen to be feeding on the bloody matter. This 



