74 William B. Herms 



VI CORRELATION OF LIFE HISTORIES TO THE SURF-PRODUCING 



STORMS 



As already intimated the surf-producing storms occur at com- 

 paratively regular intervals, a low surf taking place about every 

 three days, a heavier surf every six or seven days, and a still heavier 

 surf every fourteen or fifteen days. Now the very fact that the life 

 histories of Compsomyia macellaria, Sarcophaga assidua, Lucilia 

 caesar, and Sarcophaga sarraceniae cover, respectively, a period of 

 eight or nine days, twelve or thirteen days, fourteen or fifteen days, 

 and eighteen or nineteen days, seems to indicate a peculiar coinci- 

 dence, if nothing more. The factor 3 plays an important role, 

 viz: 3x3, 3x4, 3x5 and 3x6, which corresponds in general to 

 the occurrence of the surf. Does this signify anything, or is it 

 merely coincidence } 



In an endeavor to interpret this and to have a working basis, a 

 table was secured of the northeast and east winds (/. <?., the surf- 

 producing winds on Cedar Point) prevailing at Sandusky during 

 May, June, July and August for the years 1901 to 1905, inclusive. 

 This table was furnished through the kindness of Mr. E. H. 

 Nimmo, Director of the U. S. Weather Bureau Station at San- 

 dusky, Ohio. This table confirms in general the observations 

 made above. In it are given the dates on which the prevailing 

 winds were from the direction favorable for a surf. For the four 

 months named above in the years 1904 and 1905 are found the 

 following intervals between storms in days: 



1904—3' i4» 7' 6, 3, 6, 3, 9, 12, 6, 6, 9, 6, 6, 3, 6. 

 1905—9, 12, 4, 3, 3, 3, 2, 8, 4, 6, 3, 6, 6, 6, 9, 6, 6, 3, 9. 



It can readily be seen that 3 is again the prominent factor. 

 Fish are only cast up in quantities by a surf, and a surf is alone 

 caused by a prevailing wind from the northeast or east. These 

 fish are practically the sole food for the flies along the beach and 

 this is especially true of those individuals living on the narrow 

 strip of sand called Cedar Point, upon which the laboratory is 

 situated. Were adults to emerge from their pupa cases at a time 

 when no fish or very few fish were present on the beach the proba- 



