INSECT PESTS 321 



milk cows, whose supply of milk is noticeably increased 

 when the spray is used on them. 



Another fly pest is the common screw worm fly 

 (Compsyomia macellaria), a good-sized fly with a bluish 

 green body and a red front to its head. It lays its eggs 

 in any place where the slightest spot of blood is to be 

 found. The eggs hatch very rapidly, often in an hour, 

 yielding "screw worms." On many ranges great care 

 has to be taken in branding calves, lest they get screw 

 worms in the wound made by the burning. If a round- 

 up in the mountains is followed by a rainy spell, almost 

 every calf that was branded will have to be caught and 

 doctored, or else it will be eaten up by the worms. 



If the wound is not too deep, and in a place where she 

 can reach it, the mother will cure it with her rough 

 tongue. Frequently fresh-born calves become infected 

 about the navel and die because the worms working inside 

 the body cannot be reached by the cow. A rainy season 

 appears greatly to increase the attacks from screw 

 worms and, as a general thing, it is dangerous to brand 

 calves in the higher ranges during the rainy season. In 

 the Rocky Mountain region this is usually during July 

 and August. 



There are several patented preparations for killing 

 screw worms, and on ranges where they are known to be 

 bad every rider carries a bottle of one of them in his 

 saddle pockets, ready to care for any animal he m#y run 

 across on the range. The animal must be roped and 

 thrown, and, by means of a little wooden paddle, every 

 worm is dug out that can be reached; then the wound 

 is filled with the medicine, which kills any worms left, 

 heals the sore and keeps the flies from again depositing 

 their eggs in it. Any of the ordinary sheep dips will 



