164 



Journal of Agricultural Research 



Vol. XIII, No. 3 



out by the writer at Bethesda, Md., during the two winters of 191 5-1 6 

 and 1 916-17, but not until the winter of 191 6-1 7 was any evidence ob- 

 tained which tended to show that overwintering in the larva and pupa 

 stages was possible in the more northerly latitudes. The results of these 

 experimerts are here briefly reviewed. 



Six wooden frames 7 feet square and 2 feet high were set in the ground 

 to a depth of 6 inches. On these were placed pyramidal screened cov- 

 ers. The pyramids were slightly truncated and provided with a 6-inch 

 opening at the top, over which a large flytrap was fastened. The whole 

 was carefully fitted, so that there was no escape for flies except into 

 the trap at the top. Migrating larv^ae would have to burrow at least 6 

 inches into the soil in order to escape under the wooden sides of the 

 cages. From October 22 to 29, 191 5, 8 bushels of fresh horse manure 

 and straw were put in each box. To this was added about 5 quarts of 

 pig-manure-bran mixture, which had been collected from a heap near 

 some pigpens and which contained thousands of larvae in different 

 stages. Additions of both horse manure and pig manure were made at 

 intervals until December 8, 191 5, when there was a total of about 25 

 bushels. The pyramidal covers, with flytraps attached, were put in 

 place on November 4, and records of emergence from three cages were 

 kept during the fall and of all six cages during the following spring. 



From the three cages records of which were kept during the fall emer- 

 gence ceased after December 3, 191 5. The number and species are 

 given in Table IV. 



Table IV. — Number and species of flies emerged from three heaps of horse and pig manure 

 from, Noveryiber 4 to December j, igi5 



During the following spring emergence began April 6 and continued 

 as late as June i, 191 6. The records for all six heaps are given in 

 Table V. 



In these experiments Musca domesiica was found emerging up to 

 December 3, 191 5, but none were taken after this date, although the 

 heaps were kept under observation until June i, 191 6. The same is true 

 of Stomoxys calcitrans. Of the six species taken during the fall only one 

 {Muscina assimilis) appeared again in the spring in these traps. Eight 

 species in addition to the three or four species of the Sarcophagidae were 

 taken during the spring, and thus proved to have overwintered in the 

 larva and pupa stages. Of these Hydroiaea houghi and Ophyra leucostoma 



