458 SANITARY ENTOMOLOGY 



dumping grounds and is there allowed to decompose, or is occasionally 

 burned over, but very seldom incinerated. 



Cockroaches are found in the blood and tankage rooms, dressing 

 rooms, and other departments that are not under refrigeration. Modem 

 steel and concrete construction has much to do with eliminating these 

 insects. The use of steam and hot water in cleaning up the machinery, 

 walls and floors of all the departments and rooms containing edible goods 

 destroys Inost of them that come in during the night and do not return 

 to their better protected hiding places in the departments of inedibles 

 where there are also good breeding places. Where steam and hot water 

 cannot be used freely against roaches, the dusting of sodium fluoride is 

 very effective. About four pounds of sodium fluoride, applied with a dust 

 gun by the writer in a dry salt cellar and tankage drying room at a 

 certain packing house, killed over 5,000 roaches and thoroughly cleaned 

 away the pest. A thorough inspection of these same departments months 

 later revealed only a few roaches which probably came in from other 

 departments of the plant that were not treated. 



When skipper fly larvae are found in cured meats the products infested 

 are trimmed and the storage rooms thoroughly cleaned, or if the infesta- 

 tion is severe, the meat products are rendered for inedible purposes, the 

 uninfested products removed and the storage rooms fumigated. 



PROTECTION AGAINST INSECTS 



That flies can be kept out of packing houses to such an extent that 

 they are not objectionable is well demonstrated in some of the large 

 plants at Kansas City, Missouri; Davenport, Iowa; Omaha, Nebraska; 

 Milwaukee, Wisconsin, and Topeka, Kansas; which are completely and 

 thoroughly screened and remain remarkably free from flies on the inside 

 although flies are plentiful on the outside. 



For the protection of meats against skippers it is necessary to screen 

 closely with twenty-mesh wire. It is also necessary to keep the store- 

 rooms darkened. The use of fly traps around packing plants is fully 

 justified. Even though everything possible is done to eliminate breeding 

 places on the premises, great numbers of flies come from the surrounding 

 district to the attractive conditions which are to be found around packing 

 establishments. Our investigations have shown that flies quickly come to 

 slaughter houses when liberated at nearly a mile distant. No doubt they 

 often travel much farther to such establishments. Traps of various 

 models are used extensively at packing plants and where traps are well 

 handled great quantities of flies are captured. Accurate records kept by 

 some plants show that as high as 285 pounds of flies were captured in 



