June, '14] HUNTER: HOUSE-FLY DISCUSSION 291 



ments were so interesting, and the results so definite that, as the fly 

 season was drawing to a close, Doctor Howard and Doctor Alsberg 

 arranged to transfer the whole work to the City of New Orleans, where 

 the flies would be active for perhaps two months longer. Certain 

 series of experiments were repeated in the hope that results would 

 become so definite that something could be published and used through- 

 out the country at the beginning of the next fly season. Doctor Cook, 

 of the Bureau of Chemistry, and Mr. Hutchinson, my associate, have 

 just completed that second series of experiments in New Orleans. 

 Mr. Hutchinson is here today. In a very short time we expect to 

 place the results on record. 



In connection with this investigation we undertook to work out 

 some of the points in the life history of the fly, on which our infor- 

 mation has been very meagre, as has been pointed out by Doctor 

 Hewitt in his noteworthy work on the house-fly and Doctor How^ard 

 in his recent book. One of these points particularly was the duration 

 of the period between the emergence of the adult flies and their attain- 

 ing sexual maturity, that is, the pre-oviposition period. I think all 

 the members of the Association are familiar with the basis of the so- 

 called Hodge plan of controlling flies. In brief, Doctor Hodge's plan 

 is to ignore, at least in a large part, the breeding of flies in stable 

 manure, and devote the attack against the adults. That is the result 

 of some experiments performed some years ago by Doctor Hewitt. 

 He found the pre-oviposition period ran as high as ten to fifteen days. 

 During that time there was no danger of depositing eggs, but the adult 

 flies are going about getting food. 



We were very much interested in getting complete data. Mr. 

 Hutchinson would take a number of flies, place them in a jar with some 

 food material that would be suitable, and would leave them in a cer- 

 tain cage for 24 hours. Then they would be taken out and the cage 

 recovered, and observations made later as to whether any eggs had 

 been deposited or any larvae could be found. In a second cage the 

 flies remained there 48 hours, and so on up to an indefinite number of 

 24-hour periods. In this way we hoped by the repetition of the experi- 

 ments to obtain absolutely accurate information on this point. The 

 results have not been assembled completely at this time, but the indi- 

 cations are very plainly that this pre-oviposition period is much shorter 

 than the preliminary experiments of Doctor Hewitt had indicated. 

 That emphasizes the importance of the point brought out by Doctor 

 Headlee — the absolute importance of directing efforts against the place 

 where they might be breeding. 



Just one other point. Doctor Headlee and Doctor Hewitt have both 

 referred to the limited distribution of the fly larvae in the piles of 



