LIFE-HISTORY OF STOMOXYS CALCITRANS 199 



The abdomen is broad in proportion to its length, and each of the 

 large second and third segments has a single median and two 

 lateral brown spots ; there is also a median spot on the fourth 

 segment. The fourth longitudinal or median nervure (cf. fig. 7, 

 M. 1+2) of the wing in *S'. calcitrans has not the pronounced 

 angular bend found in the same nervure in 31. dornestica. 



The life-history was first studied in anything like a complete 

 manner by Newstead (1006) and I was able to confirm his 

 observations during 1907, lf)08 and 1912. Portchinsky added to 

 our knowledge in 1910. In the United States Bishopp (1913) 

 has recently made a valuable contribution to the knowledge of 

 the insect's biology and life-history, and Mitzmain (1918) has 

 given a summary of his investigations in the Philippine Islands 

 which have extended over two years. These references are given 

 as it is not intended to give an exhaustive account of this insect 

 here. It may be added that morphological studies have been 

 made by Newstead, Tulloch (1906) and Brain (1912). The fol- 

 lowing account of the life-history is taken from the foregoing 

 accounts and my own notes. 



Both sexes are able to suck blood. After emerging from the 

 puparium the proboscis lies extended backwards, along the ventral 

 side of the thorax. It soon bends forward and hardens, and in 

 six to eight hours after emergence the fly may take its first meal. 

 The feeding period lasts from two to twenty minutes. It has 

 been found to feed chiefly on cattle, horses, dogs and man, being 

 especially attentive to the ears of dogs. Bred flies may begin 

 ovipositing on the ninth day, usually after they have had the 

 third or fourth feed. This species breeds in the following sub- 

 stances, apparently with varying preferences in different countries : 

 horse manure, cow manure, sheep dung, human excreta, the straw 

 of oats, rice, barley and wheat, fermenting cut grass, decaying 

 vegetable substances, including fungi, and in animal substances, 

 no doubt in a state of decomposition. 



The eggs may be laid singly or in batches of as many as 

 seventy-two (Newstead). The eggs are white, cylindrically oval 

 in shape, somewhat resembling a banana, and measuring 1 mm. in 

 length. A groove Avidening at the anterior end runs along the 

 side of the agg. Mitzmain states that the maximum number of 



