366 LIFE STORIES OF AUSTRALIAN INSECTS. 



Family (Estridae: In this family we have ''hot 

 flies," ''sheep bots or sheep nostril flies" and 

 ''warble flies." Of warble flies Froggatt records: 

 "The members of the genus Hypoderma are a very 

 serious pest in Europe or other countries where they 

 infest cattle, and are known as 'warble' or 'bot 

 flies.' The fly lays her eggs upon the back of the 

 beast ; the tiny larva makes its way through the hide, 

 beneath which it lives and feeds upon the putrid 

 matter caused by the irritation of its presence: it 

 finally produces an inflamed blister-like swelling or 

 'warble,' eventually working its way out through 

 the hide and falling to the ground where it buries 

 itself in the ground. " It is not found in Australia. 



In tliis family are som§ very serious pests. The 

 bot fly {Gastrophihis) (Plate 45) attacks horses. 

 The mother fly lays her eggs on the head, shoul- 

 ders, and front legs of the horse. They adhere firmly 

 to the hairs, for they are fastened by a sticky 

 secretion. They are licked off by the horse, and 

 the saliva loosens the eggs from the hairs. The 

 maggots hatch out in the horse's mouth, and are 

 carried down to the stomach. The maggot is not 

 smooth like most maggots, but has a serrated "frill" 

 on the edge of each exposed segment. (Plate 45, 

 Fig. 1.) It also has a strong pair of jaws, by means of 

 which it clings to the tissue of the horse's stomach, 

 where it absorbs its liquid food and develops. (Plate 

 45, Fig. 3.) These maggots are called bots. At last 

 the bot is "grown up," and loosens its hold and is 

 carried out of the horse's body in the excrement. It 

 pupates in the soil. 



