PREVENTIVE MEASURES 179 



in the following way : "Macerate during twenty-four 

 hours i,ooo parts of quassia wood with 5,000 parts 

 of water, then boil for half an hour; set aside for 

 twenty- four hours and press. Mix the liquid with 150 

 parts of molasses, and evaporate to 200 parts. A 

 weaker decoction of the quassia does not kill the flies. 

 From this the fly water or fly plate is prepared as fol- 

 lows : Mix when needed and dispense without filter- 

 ing, 200 parts of syrup of quassia, fifty parts of alcohol 

 and 750 parts of water. It is used by moistening with 

 the mixture a cloth or filtering paper on a plate." 



The native ore of speiss cobalt is found in commerce 

 under the name of flystone, and was at one time ex- 

 tensively used for poisoning flies by roughly grinding 

 it and putting a small quantity in a saucer with sweet- 

 ened water. 



It is possible to poison flies rather satisfactorily by 

 putting a lump of sugar in a saucer partly filled with 

 water and adding white arsenic. This, of course, is 

 dangerous where there are children or house dogs or 

 cats about. 



Of the unpatented fly traps, a device was recom- 

 mended by Mr. P. J. Parrott, Entomologist of the 

 Kansas Experiment Station, in Bulletin 99 of the Sta- 

 tion (October, 1900), as follows: 



"The department of entomology, after experimenting 

 upon various mechanical devices for catching flies, has 

 contrived a trap and recommended it for trial on ac- 

 count of its effectiveness and cheapness. Anybody 

 with an average amount of mechanical ingenuity can 



