MYIASIS— ITS PREVENTION AND TREATMENT 203 



large opening at the top of tlie cone, screened area over the cone to admit 

 light from above, screened sides so as not to cast shadow around the 

 bait, and legs about one inch higli. The tent traps are not as efficient 

 as the cone traps and this inefficiency is especially marked in some 

 makes of traps now being furnislicd the Army, which are built with a 

 broad bottom on either side of the tent. This repels the flies to such an 

 extent as to make the traps almost worthless. For blow flies this dark- 

 ened area is not so objectionable as for the house fly. While not strictly 

 a trap, the method of covering carcasses with burlap as recently sug- 

 gested by Froggatt in Australia may be of value. Four stakes are driven 

 into the ground around the carcass, and the tops of these are connected 

 with a heavy wire. A canopy is then put over the stakes, brought to 

 the ground and dirt piled on the edges. When the flies emerge they are 

 imprisoned and soon die. If the canopy is not sufficiently large, there 

 is danger of many escaping through the migratory habit of the larvae. 



Kind of Bait to Use. — This point has been discussed in a previous 

 lecture. Animal matter is best for blow flies, and the packing-house ref- 

 use known as "gut slime" is best of all. It is removed from intestines 

 when sausage casings are made. Good baits and proper attention to kill- 

 ing and rebaiting are essential to best results. 



Poisons. — It is possible to destroy large numbers of flies by means 

 of poisoned baits. Arsenic solution (made by boiling arsenic in water) 

 mixed with defibrinated blood, gut slime, or some other attractive bait 

 will kill large numbers. This bait may be placed in covered containers 

 to prevent dilution by rain. Cobalt may be substituted for arsenic. 

 When carcasses can not be burned, Froggatt has advocated slashing 

 them and spraying with arsenic solution. This poisons large numbers 

 of flies and maggots and reduces the attractiveness of the carcass ; so 

 much so, in fact, that birds and animals will not touch it. 



Avoidance of Attack on Man. — To prevent fly attack it is necessary 

 to have wounds promptly and properly dressed. Man should avoid 

 exposure by sleeping in the open during hot weather, especially if there 

 is any trouble from catarrh or nose bleeding. Properly screened hos- 

 pitals are of much importance and individual blow flies found within 

 should be promptly killed. 



Avoidance of Attack to Animals. — In preventing screw-worm attack 

 in cattle and other livestock, there are several important points to be 

 considered. Breeding should be done so as to have calves come during 

 fall, winter or early spring months. Branding and surgical operations 

 should also be done out of screw-worm season. Care should be taken 

 to avoid mechanical injury to stock. As the screw-worm flies are worst 

 in brushy pastures, clearing out all underbrush will be found beneficial. 

 Since many cases develop from infestation of ticks and mange, the de- 



