1 78 INSECTS 



membrane itself and, if pressed for food, upon the 

 muscular tissue. When the infestation is a bad one 

 they work their way, through all the openings between 

 or in the bones, to all parts of the head cavity, and into 

 the brain itself, in such cases causing "staggers" and 

 death. The larvae like almost all bots are set with 

 short stiff spines, definitely arranged, that enable them 

 to make their way forward, and there is also a pair of 

 mouth hooks that enables the grub to fasten itself 

 firmly to any place selected. This spiny structure and 

 the definite mouth hooks are not developed in the 

 "screw-worm," which is a typical maggot, altogether 

 unlike the highly developed "bot. " The amount of 

 damage caused by the sheep bot is very great in many 

 localities, while in others the species seems to be alto- 

 gether unknown. As to remedies against them, each 

 locality or herdsman has its or his own, and none is 

 entirely satisfactory. 



An altogether different type of bot is that which 

 occurs in horses. The fly that produces this has rather 

 a conical pointed abdomen and a brown hairy body. 

 The eggs are laid on and attached to the hair, usually 

 on the forelegs or on some part easily reached by the 

 horse with its head; and they remain there, unhatched, 

 although the embryo may be fully developed, until 

 the horse in licking itself or a companion dislodges 

 the egg-cap and, freeing the larva, transfers it to the 

 mucous membrane of the mouth. From this place it 

 moves at once and makes its way down the oesophagus 

 into the stomach. Here the young bot finds its proper 

 conditions and becomes anchored by means of a pair 

 of mouth hooks into the lining membrane. It feeds 

 here, absorbing the juices for several months, maturing 

 in late spring, and then loosens its hold, is carried into 

 the intestines with the excrement and so on through 



