April, '17] BISHOPP. FLIES AND ABATTOIRS 271 



with a. problem not only of preventing the breeding of flies on their own 

 premises, but of destroying those which are so freely contributed by 

 surrounding breeding places. In addition to those insanitary condi- 

 tions mentioned, it is not infrequent to find rendering plants, both for 

 garbage and dead animals, glue works, fertilizer factories and city 

 sewer discharges located in the same districts. Fortunately, engi- 

 neers have devised means of greatly reducing the amount of odor given 

 off by the various manufacturing processes involved, and still further 

 development along this line in under way. This should render not 

 only the establishments less attractive to flies, but should also aid in 

 improving city conditions in the vicinity of such plants. 



Another condition, which is somewhat different from that encoun- 

 tered in most fly control work, is the accumulation of large amounts 

 of material of vastly- different kinds which, when not receiving proper 

 attention, produces abundant breeding places for many species of in- 

 sects. For example, it was formerly not uncommon to find on some 

 packing house premises, enormous piles of manure from cattle paunch 

 — in some cases several hundred feet long — tons of undried blood and 

 meat tankage often infested with maggots when shipped in from smaller 

 plants, carloads of bones of various kinds which furnished admirable 

 breeding conditions for a number of species of blow-flies, thousands of 

 sheep pelts which in some cases were air-dried and bred flies during the 

 process, warehouses full of hoofs, horns and various classes of dried 

 bones which produced swarms of hide and ham beetles as well as skip- 

 per-flies. In the immediate environs of slaughter plants it was for- 

 merly the practice to dry hog hair on the ground. In some instances 

 acres of hair fields were found, and during the drying these bred num- 

 bers of flies beyond comprehension. Sometimes great areas exist in 

 the vicinity which are covered with manure removed from stock yards 

 and in cleaning cars. Numerous temporary breeding places are pro- 

 duced by the breaking or clogging of pipes or boiling over of stick- 

 water vats which may render many square j^ards of earth suitable for 

 breeding myriads of flies. In some of the large plants the fertihzer 

 industry is carried on in large proportions. The receipt of many cars 

 of dried bones at such establishments is not uncommon, and we have 

 found these to be fertile breeding places for the so-called skipper-fly. 

 Many other conditions favorable for fly attraction and breeding might 

 be cited. 



There are some advantages in the usual grouping together of a num- 

 ber of packing establishments in one district, for in these cases the 

 operators usually have complete control of such districts and if they 

 assume the proper attitude much beneficial work can be done through 

 them. While the meat inspection service does not exercise direct 



