82 NA T U RE-STUD Y RE VIE W [12 :2— Feb. , 1916 



as I have seen them do constantly in the ordinary traps — we have 

 been giving them food to make eggs with. The crack at the bot- 

 tom, through which the flies go in must not be over one-quarter 

 inch wide, and it must open up toward the bait, so that a fly, 

 after feeding, will have to crawl down in order to escape. This 

 it almost never does, hence with a trap rightly made we catch all 

 the flies that are attracted to our baits. The fly possesses no 

 more cunning than shot rolling off a roof, hence it is only a matter 

 of mechanical arrangement to catch the last one as easily as the 

 first. This point is illustrated in Fig. 4. 



The net, too, is a " Getthelastone" proposition for any strag- 

 glers about the house that are attracted to the kitchen rather than 

 to the traps at the back door or in the barnyard. If ready for 

 them early in the spring, we shall have to catch very few in order 

 to make extermination complete. 



Just now the wildest confusion reigns as to plans and methods. 

 For in the same breath we are told to kill the last fly and be sure 

 to screen all doors and windows. Clearly, if we really did the 

 former, we could save the expense and be free from the nuisance 

 of screens. The most illogical and impossible directions are issued 

 regarding disposal and treatment of refuse matter in which flies 

 may breed. "Fly tight" stable receptacles have been widely 

 ordered by boards of health, entailing considerable labor and ex- 

 pense. The writer has inspected hundreds of these and has yet 

 to see the first one really fly tight. The material in all of them 

 in fly time has been rolling with maggots, because most of the 

 eggs are laid before the material is put into the receptacle. We 

 do not need to incur this labor and expense, if there are no breeders. 

 Time consuming, laborious and somewhat expensive methods 

 have been worked out for chemically treating barnyard manure to 

 prevent maggots from developing in it. First powdered borax 

 at the rate of 0.62 pound per eight bushels or ten cubic feet 

 (works better, if applied in solution or if wet down after the powder 

 has been evenly dusted over the pile) was recommended. This 

 was found to kill about 90 per cent of the maggots, (how easy in 

 comparison to catch 100 per cent of the flies after they had hatched, 

 or before they laid the eggs) and if used on the land at the 

 rate of more than 15 tons per acre, it was likely to be injurious 

 to crops. The cumulative effects upon the soil of successive 

 applications is also unknown. However, borax may be used to 



