98 Journal New York Entomological Society. [^'o'- ^^• 



Jones says : " Like mosquitoes, they seem unable to breed in water 

 affected by the tide, but prefer the smaller pools that are practically 

 without motion. ... I have found the flies living in ponds where the 

 salinity was as high as 4.2 per cent., being almost one per cent, higher 

 than that of average sea water. . . . The adult flies abstract their 

 nourishment from the surface of the water in which their larvre live. 

 Tliey are especially fond of decaying animal matter, and will collect 

 in swarms on water containing dead crabs or other animal bodies.'' 



At Santa Monica the species was abundant July 11, 191 1, on the 

 surface of a pool at the mouth of Santa Monica Creek. The creek is 

 small, and disappears in the sand as it approaches the beach. Here 

 there was a pond some 15 feet wide and 70 long, with no visible outlet 

 or inlet, on which were the flies, but in which I could find no larvae 

 even in prolonged search. 



Explanation of Plates. 



Plate I. 



Fig. I. Ephydra gracilis Pack., adult $, X 8. 



Fig. 2. Ephydra gracilis Pack., nearly full-grown larvse, X 4/^. 



Fig. 3. Ephydra gracilis Pack., cluster of puparia hanging together by 

 anal tubes, X 3. 



Fig. 4. Ephydra gracilis Pack., mass of dried puparia from Great Salt 

 Lake beach, slightly reduced. 



Fig. 5. Ephydra siibopaca Loew, adult J, X 8. 



Fig. 6. Ephydra millhrcc Jones, adult $, X 8. 



Fig. 7. Ephydra hians Say, dorsal anterior dehiscent portion of puparium, 

 enlarged (see Fig. 16, arrow). 



Pl.vie 11. 



Fig. 8. Looking east from Promontory Point, Utah, along the S. P. cut- 

 off. The dark material collected in the bay in the foreground is Ephydra 

 gracilis puparia. 



Fig. 9. Looking west on the south side of the railroad near Fig. 8. The 

 puparia of gracilis form the dark deposit along the edge of the water. 



Fig. 10. Ephydra gracilis on railroad rails at Lakeside, Utah ; the near 

 rail on the right is focused best. 



Pl.^te III. 



Fig. II. Ephydra hians Say, eggs, X 40. 



Fig. 12. Ephydra hians Say, young larva, X 24. 



