BREEZE-FLIES. 29 



pears to be composed of eleven segments, surrounded with 

 a double row of horny bristles, a longer and a shorter series, 

 and placed alternately : the two last segments appear to be 

 naked or destitute of them. These spines are of a reddish 

 colour, except the points, which are black, and are directed 

 towards the tail or large end of the Ian- a. 



The larva, when matured, quits the stomach of the ani- 

 mal and falls to the ground, and finding a convenient place 

 of retreat, undergoes its change to a chrysalis, the skin 

 then losing its organization, and changing in colour to a 

 reddish brown. After remaining torpid in the chrysalis 

 state a few weeks, the superfluous moisture being removed 

 and the parts of the future insect hardened by drying, it 

 bursts from its confinement, and the fly makes its exit at 

 the small end of the case. A few hours after quitting their 

 shell they become dry, take wing, and seek their mates. 



A second species of breeze-fly has a still more wonderful 

 history : its eggs are laid in the nostrils of sheep, from one 

 to seven or eight in each individual, and these on becoming 

 larvae, enter the frontal and maxillary sinuses, and even 

 the horns, and feed on their secretions : when the larvae 

 are young they are perfectly white and transparent, ex- 

 cept two small, black, horny plates : as they increase in 

 size the upper surface becomes marked with two transverse 

 brown lines on each segment, the anterior being shorter and 

 narrower than the posterior ; and some spots are also obser- 

 vable on the sides. The body consists of twelve segments 

 besides the head. These larvae move with considerable 

 activity, holding with their tentacula to a fixed point and 

 drawing up the body. When full grown the larvae fall 

 through the nostrils of the sheep, and change to the pupa 

 state lying on the earth or adhering to the side of a blade 

 of grass : in about two months the case of the chrysalis 

 opens, and the fly makes its appearance. 



