292 JOURNAL OF ECONOMIC ENTOMOLOGY [Vol. 7 



manure. In connection with this series of experiments at the Arlington 

 farm, Mr. Hutchinson was astonished one day to find that a large num- 

 ber of his larvae were escaping. He began to investigate the matter. 

 By examining many piles of manure near Washington he found a 

 concentration of larvae and pupse in the peripheral ring near the outer 

 surface. Immediately he considered the factors of moisture and 

 temperature, that might be instrumental in bringing about this 

 condition. The result of the observations of Mr. Hutchinson led him 

 to the belief that moisture is more important than temperature. In 

 fact, he has performed a series of experiments, in which he has regu- 

 lated practically the location of the pupce by the administration of 

 water. This led to one point, that may be of great importance. He 

 has found that, where the manure piles are completely saturated with 

 water, the larvae will make their way outside. The instinct of the 

 larvae is to obtain a location where there is an optimum of conditions 

 and where the adults can make their exit. A practical application in 

 a stable would be to throw the manure upon a frame work and keep 

 it saturated with water. By that system the experiments show the 

 larvae will all fall through the bottom to the floor. In the case of a 

 cement floor, it would be possible to flush them into the drain, or 

 dispose of them some other way. On a farm the manure might be 

 placed on a platform and the larvae forced by the application of water 

 to make their way out to be eaten by the chickens. 



I would like to congratulate Doctor Hewitt on this very important 

 work that he has done. I think that all the members of the Association 

 think that the high standard, that he set, when he wrote the book on 

 the house-fly, has been maintained by the series of practical experi- 

 ments, which he has described this morning. 



Mr. C. Gordon Hewitt: A number of years ago when I carried 

 on house-fly work, I was able to devote all my time to it. Now it is 

 possible for me to carry it on only during spare time. I would urge 

 Doctor Howard and his associates to con+inue to carry on these experi- 

 ments as they are very important. With regard to the pre-oviposition 

 period, the single series of experiments which I carried on in Man- 

 chester, England^ gave but few results and were not intended to do 

 more than to give general information. The mean temperature in 

 Manchester, England, is much less than in this country, consequently 

 the pre-oviposition period there would be longer. 



In the experiments which I mentioned in my paper I found that flies 

 were emerging on the outside of the wooden cages before the cheese- 

 cloth bottom was attached. During the hot days the newly emerged 

 flies crawled up on the outside of the cages and the males copulated 

 with the females immediately. This shows that the female fly may 



