OF WASHINGTON, VOLUME XVIII, 1916 197 



Mr. Speare has since found two somewhat similar specimens in 

 the Pergande collection, but in each case the Cordyceps growths 

 i-suing from the wing sutures are uncapped. 



In discussing this last note, Doctor Townsend said that he 

 considered that the fly \vas probably a dexiid and that it suc- 

 cumbed immediately after issuing from the puparium, which 

 accounted for its much shriveled condition and for the absence 

 of wings, the Cordyceps growth issuing from the body at the wing 

 sutures. 



A PRELIMINARY NOTE ON THE BIONOMICS OF POLLENIA 

 RUDIS, FABR. IN AMERICA. 



BY J. L. WEBB AND R. H. HUTCHISON. 



The discovery during 1908 of the larva of Pollen in ///(//*. Fabr. 

 by Keilin and subsequent studies by him have brought to light 

 many facts on the life history of this common fly, which had up 

 to that time remained a complete mystery. In a recent article 

 Keilin reviews his extensive investigations, (Keilin, D. "Re- 

 cherches sur les Larves de Dipteres Cyclorhaphes," Bui. Sci. de 

 la France et de Belgique, T. XLIX, 7e Serie, 30th Dec., 1915) 

 and we give here a brief summary of the main points bearing 

 directly on the life history of Pollenia. The reader is referred 

 to the original article for an interesting discussion. 



Keilin found the larvae of Pollenia rudis parasitic on the 

 earthworms, Allolobophora chlorotica and A. rosea. Eggs are de- 

 posited during August or early September on the soil. They 

 hatch after five to seven days and the larvae, when they find an 

 earthworm, gain entrance to the body through the male genital 

 opening located on the ventral side of the 15th segment. From 

 September or October to the following May or June the Pollen in 

 larvae are found in a dormant state in the body cavity of the 

 genital segments, i.e. from the 9th to the 12th or even as far 

 back as the 16th. In May or June the larvae becomes active, 

 works its way toward the anterior end of the worm, where it 

 pierces with its posterior end the prostomium of the worm and 

 thus exposes its stigmata. It continues to feed and gradually 

 destroys the worm, working backward as fast as the segments 

 are destroyed. Pupation occurs usually from the r>ih to the 25th 

 of June, and the pupal stage has a duration of from 32 to 4f> days, 

 emergence occurring from the middle of July to the first part of 

 August. 



