ENTOMOLOGY

CONTROL OF FLIES IN BARN YARDS AND PIG PENS 169The use of manure pits and boxes has been mentioned in a previouslecture, as has also the Hutchison maggot trap. It appears to thewriter that any attempt to construct pits or boxes which are so tightas to prevent the escape of newly emerged flies is likely to meet withfailure. In practically all instances the manure is infested more orl.ess when placed in the box or pit, and following this suggestion thewriter has been advocating the placing of the manure in boxes and pitswhich 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 almostsurely escape to the light from the most ti~htly constructed box or pitwhich it is feasible to build and maintain. A manure box of Jhistype has been tried by the Dallas laboratory and found to work admirably.The number of flies caught is often surprisingly large.For small pastures and meadows it is sometimes feasible to utilize abrush drag to break up the cow droppings. This serves three purposespreventingthe breeding of the horn fly, scattering the manure evenlyover the ground, and permitting the grass to grow where it would otherwisebe prevented by the piles.While the house fly does not breed readily in pure cow manure thewriter has reared the species from this substance and has also foundthat where cow manure is mixed with a certain amount of straw it is afairly good breeding medium for this species. The horn fly, Lyperosia.irritans (Haematobia) Linnaeus, breeds exclusively in cow droppingseither in large piles or individual droppings. Blow flies are not known tobreed in cow manure, but a number of species of Sarcophagids, most ofwhich, however, do not have scavenger habits, breed in considerable numbers.The brilliant green fly, Pseudopyrellia comicina Fabricius (plateIII, fig. 4), is very commonly seen on fresh cow droppings; in fact this isusually the most abundant species in this situation in the country. Itmay ·be readily mistaken for Lucilia when not examined carefully. Thisspecies is of no importance as a human disease carrier as it does notenter '}lOuses or visit food. 2In preventing flies breeding in yards it is very essential that watertroughs be kept from running over and whenever overflows or leaks dooccur they should be fixed promptly and the moistened manure and earthcleaned up and hauled away immediately. Special attention should begiven to accumulations of horse manure in yards along feeding racks.Here the mixture of horse manure, waste hay and urine forms a satisfactorymi~ture for fly production.I Unquestionably its larvae must have an important rlile as regards organisms takenup from the manure and passed through their bodies, but whether this rlile is to destroythe organisms or to propagate and distribute is yet to ·be learned.-W. D. Pierce.