358 STOMOXYS [CH. 



gives a true indication of its usual habitat, and during the sum- 

 mer large numbers of Stomoxys may generally be found around 

 the cow-sheds and stables of any farmyard ; in warm weather, 

 however, it may be found wherever cattle are grazing ; and 

 during late summer and autumn they are frequently found 

 in houses, where they are known as "Biting House-flies." 

 When resting on a wall, Stomoxys generally points the head 

 upwards, and thus may be distinguished from the house-fly 

 which usually takes the opposite position. 



The fly may feed on the juices from any decaying organic 

 matter, and also on the blood of vertebrates. It is possible 

 that its blood-sucking habits have been somewhat over-esti- 

 mated, for Newstead kept a careful watch on both horses and 

 cattle in a farmyard where Stomoxys were plentiful without 

 seeing even one settle on an animal. During hot weather, 

 however, the flies become very troublesome to animals and 

 may even attack human beings. The voracious habits of 

 Stomoxys are well shewn when a number are kept together in 

 captivity. Under these circumstances if an individual suffers 

 any injury, the others at once try to feed on it and, if success- 

 ful in piercing the integument, suck all the contents out of 

 their unfortunate companion. 



Unlike many blood-sucking flies, the female Stomoxys will 

 lay fertile eggs without ever having fed on blood. 



Life history. Newstead has recently given a complete 

 description of the metamorphosis of this insect from which the 

 following account is taken. The female generally lays its eggs 

 a few inches below the surface in stable manure, decomposing 

 vegetable matter, or similar materials. Although the flight 

 of this insect is usually noiseless, when the female is preparing 

 to oviposit the noise of its wings is distinctly audible, resembling 

 the hum made by most other members of the Muscidae. The 

 eggs are generally laid in an irregular heap and their number 

 is usually about 50 to 70. The egg is i mm. in length, very 

 elongate, shaped somewhat like a banana, being curved on one 

 side and deeply grooved on the other. This groove widens 

 towards the anterior end. The colour of the egg is white 

 when first laid, but subsequently becomes creamy-white. 



