12 farmers' bulletin 857. 



from strong winds and the sun. They may be baited with carcasses 

 of freshly killed animals such as rabbits or prairie dogs. The bait 

 should be changed every three or four days to prevent maggots from 

 breeding in it, and the flies should be killed and emptied when the 

 trap becomes too full. 



Most liquid poisons evaporate so rapidly that they are of little use 

 under range conditions. Wliere dead animals can not be promptly 

 burned or buried it is possible to kill a large number of flies by using 

 the carcasses as poisoned baits. The animal should be partially 

 skinned, the flesh slashed, and a solution of arsenic made by boiling 

 1 pound of white arsenic in 5 gallons of water applied freely to the 

 flesh. This method has been recommended by Prof. W. W. Froggatt 

 in combating the sheep-maggot flies in Australia. He says that an 

 animal will remain attractive for a couple of days only, owing to the 

 hardening action of the arsenic on the flesh. The animal then may 

 be turned over and treated the same way on the other side, after 

 which it may be buried, or, if this is impossible, fly breeding is pre- 

 vented by the action of the arsenical solution, and it is said that birds 

 and animals will not touch the carcass. Small wild animals killed in 

 pastures may be used as poisoned baits in the same way. 



TREATMENT OF INFESTED ANIMALS. 



It is important that herds be watched carefully during the screw- 

 worm season so that all cases of infestation ma}^ be detected early. 

 Those familiar with screw-worm injury have very little difficulty 

 in telling if a wound is infested. Usually there is a free discharge of 

 watery blood and a fresh appearance to the wound. In handling 

 these cases on ranches it is best to have a small pasture, usually called 

 a " trap," close to headquarters, where all infested animals are kept 

 until the wounds are completely healed. 



The construction of large cages of screen wire or netting such as 

 shade cloth, used in covering tobacco, has been found practicable for 

 the protection of valuable calves born in the screw-worm season. 

 Moreover, such cages are useful for protecting injured stock from 

 infestation or for allowing wounds already infested to heal following 

 treatment without suffering further attack. 



For destroying the maggots in a wound nothing better than 

 chloroform has been found. One of the principal advantages of this 

 material is that it evaporates freely and penetrates to the deeper 

 parts of a wound. If the infested place has a comparatively small 

 hole at the skin, but is deep, it is a common practice to pour chloro- 

 form into it and then plug the hole. In most cases it is desirable to 

 remove the dead or comatose maggots with a pair of forceps, clean 



