158 Arthropods as Simple Carriers of Disease 



Manure, garbage, and the like should be stored in tight receptacles 

 and carted away at least once a week. The manure may be carted 

 to the fields and spread. Even in spread manure the larvae may con- 

 tinue their development. Howard points out that "it often happens 

 that after a lawn has been heavily manured in early summer the 

 -occupants of the house will be pestered with flies for a time, but 

 finding no available breeding place these disappear sooner or later. 

 Another generation will not breed in the spread manure." 



Hutchinson (1914) has emphasized that the larvae of house- 

 flies have deeply engrained the habit of migrating in the prepupal 

 stage and has shown that this offers an important point of attack 

 in attempts to control the pest. He has suggested that maggot 

 traps might be developed into an efficient weapon in the warfare 

 against the house-fly. Certain it is that the habit greatly simplifies the 

 problem of treating the manure for the purpose of killing the larvae. 



There have been many attempts to find some cheap chemical 

 which would destroy fly larvae in horse manure without injuring the 

 bacteria or reducing the fertilizing values of the manure. The litera- 

 ture abounds in recommendations of kerosene, lime, chloride of lime, 

 iron sulphate, and other substances, but none of them have met the 

 situation. The whole question has been gone into thoroughly by 

 Cook, Hutchinson and Scales (1914), who tested practically all of the 

 substances which have been recommended. They find that by far 

 the most effective, economical, and practical of the substances is 

 borax in the commercial form in which it is available throughout the 

 country. 



"Borax increases the water-soluble nitrogen, ammonia and alkali- 

 nity of manure and apparently does not permanently injure the 

 bacterial flora. The application of manure treated with borax at the 

 rate of 0.62 pound per eight bushels (10 cubic feet) to soil does not 

 injure the plants thus far tested, although its cumulative effect, if 

 any, has not been determined." 



As their results clearly show that the substances so often recom- 

 mended are inferior to borax, we shall quote in detail their directions 

 for treating manure so as to kill fly eggs and maggots. 



"Apply 0.62 pound borax or 0.75 pound calcined colemanite to 

 every 10 cubic feet (8 bushels) of manure immediately on its removal 

 from the barn. Apply the borax particularly around the outer 

 edges of the pile with a flour sifter or any fine sieve, and sprinkle two 

 or three gallons of water over the borax-treated manure. 



