CONTROL OF FLIES IN BARN YARDS AND PIG PENS 169 



The use of manure pits and boxes has been mentioned in a previous 

 lecture, as has also the Hutchison maggot trap. It appears to the 

 writer that any attempt to construct pits or boxes which are so tight 

 as to prevent the escape of newly emerged flies is likely to meet with 

 failure. In practically all instances the manure is infested more or 

 less when placed in the box or pit, and following this suggestion the 

 writer has been advocating the placing of the manure in boxes and pits 

 which will not allow flies to gain entrance from the outside and which 

 are provided with a cone or tent trap to capture the flies which breed out 

 (see plate V). In the absence of the trap feature these would almost 

 surely escape to the light from the most tightly constructed box or pit 

 which it is feasible to build and maintain. A manure box of this 

 type has been tried by the Dallas laboratory and found to work admir- 

 ably. The number of flies caught is often surprisingly large. 



^ For small pastures and meadows it is sometimes feasible to utilize a 

 brush drag to break up the cow droppings. This serves three purposes — 

 preventing the breeding of the horn fly, scattering the manure evenly 

 over the ground, and permitting the grass to grow where it would other- 

 wise be prevented by the piles. 



While the house fly does not breed readily in pure cow manure the 

 writer has reared the species from this substance and has also found 

 that where cow manure is mixed with a certain amount of straAV it is a 

 fairly good breeding medium for this species. The horn fly, Lyperosia 

 irritans (Haematobia) Linnaeus, breeds exclusively in cow droppings 

 either in large piles or individual droppings. Blow flies are not known to 

 breed in cow manure, but a number of species of Sarcophagids, most of 

 which, however, do not have scavenger habits, breed in considerable num- 

 bers. The brilliant green fly, Pseudopyrellia cornicina Fabricius (plate 

 III, fig. 4), is very commonly seen on fresh cow droppings; in fact this is 

 usually the most abundant species in this situation in the country. It 

 may be readily mistaken for Lucilia when not examined carefully. This 

 species is of no importance as a human disease carrier as it does not 

 enter houses or visit food.^ 



In preventing flies breeding in yards it is very essential that water 

 troughs be kept from running over and whenever overflows or leaks do 

 occur they should be fixed promptly and the moistened manure and earth 

 cleaned up and hauled away immediately. Special attention should be 

 given to accumulations of horse manure in yards along feeding racks. 

 Here the mixture of horse manure, waste hay and urine forms a satisfac- 

 tory mixture for fly production. 



* Unquestionably its larvae must have an important role as regards organisms taken 

 up from the manure and passed through their bodies, but whether this role is to destroy 

 the organisms or to propagate and distribute is yet to be learned.— W. D. Pierce. 



