178 SCHOOL ENTOMOLOGY 



cumstantial evidence that tuberculosis, anthrax, yaws, oph- 

 thalmia, small-pox, tropical sore, and parasitic worms may 

 be, and are, so carried. Actual laboratory proof exists in 

 the cases of a number of these diseases, and where lacking, is 

 replaced by circumstantial evidence amounting almost to 

 certainty." (Howard.) 



The screening of windows and doors and the use of sticky 

 fly-papers are preventive measures known to all. A two 

 per cent solution of formaldehyde will destroy the flies and 

 may be placed in shallow saucers to which they will be at- 

 tracted. Adding milk or syrup and dropping in a piece of 

 bread will make it more attractive. Where flies or mos- 

 quitoes become too numerous they may be destroyed by 

 fumigating with pyrethrum powder. About one pound 

 should be used for every 1000 cubic feet of space. Place 

 the powder on pans, dampening with a little kerosene into 

 cone shapes, to facilitate burning. Make all windows and 

 doors as tight as possible, light the cones, and leave over 

 night. The fumes are not poisonous to persons and will not 

 injure furnishings. The chief effort in the control of house 

 flies should be directed toward preventing their breeding in 

 horse manure, for a single stable will supply flies for a whole 

 neighborhood. As far as possible manure should be kept 

 in a tight box or pit which can be properly screened where 

 necessary. Recent experiments * of the U. S. Department of 

 Agriculture (26) have shown that the eggs and maggots in 

 the manure may be destroyed by the use of borax or calcined 

 colemanite. Ten ounces of borax or 12 ounces of calcined 

 colemanite should be used for every 10 cubic feet (8 bushels), 

 of manure immediately upon its removal from the barn. 

 Apply the borax with a flour sifter or any fine sieve, particu- 

 larly around the edges of the pile, for there is where most of 

 * Bulletin 118, U. S. Department of Agriculture. 



