THE STRUCTURE OF THE BLOW-FLY 143 



comes outside the bases of the mid and hind legs, close to 

 the root of the rudimentary hind wing. The metathoracic 

 spiracle is easily seen as a nearly vertical slit, the other is not 

 so obvious. 



There are at least eight segments in the abdomen. The 

 first is concealed by the thorax, while the sixth, seventh, 

 and eighth are telescoped into the hinder end of the body, 

 from which they can be made to protrude by gentle pressure. 

 In the male the segments so protruded exhibit three terga, 

 to the last of which are attached two pairs of appendages. 

 The outer pair of appendages are larger than the inner, and 

 curve inwards at the tip. These are prehensile organs, used 

 for seizing the female. I'he abdominal sterna do not overlap 

 like the terga, but are separated by rather wide spaces of 

 flexible membrane. The loose articulations of the sterna, 

 and the sliding movements of the terga, allow of considerable 

 distension of the abdomen. In the female the segments 

 protruded by pressure take the form of a long conical process, 

 consisting of several segments, four terga and five sterna 

 being easily made out; the last carries a pair of small 

 appendages. 



Observe the wings and their insertion. At the base of 

 each, and in the angle between the wing and the body, are 

 two semi-circular . folded lobes of the wing, of which the 

 inner one (the winglet) forms a dome-like covering to the 

 haltere. The hind wings (halteres) are small, and incapable 

 of aiding in flight. They form narrow stalks, clubbed at 

 the ends, and may be seen on removal of the winglets. 



Each of the six legs consists of a broad coxa, a short 

 trochanter, a femur, a long and narrow tibia, and a five- 

 jointed tarsus. The last joint of the tarsus is provided with 

 a pair of hooks and a pair of pads. The pads adhere to 

 smooth surfaces by means of a sticky secretion which flows 

 from them. 



The male blow-fly is easily distinguished from the female 

 by the large size of the compound eyes, which meet upon 

 the face. The abdomen is slighter, and seems nearly empty 

 when pressed. Male blow-flies are seldom seen in houses, 

 but are common in gardens, where they may be found visiting 

 flowers, or sunning themselves on banks. 



The eggs are laid in packets of various size, upon carcasses 



