10 BULLETIN" 329, TJ. S. DEPARTMENT OF AGRICULTURE. 



egg about every two seconds, as fast as she could extend and retract 

 her ovipositor. Ten eggs were laid in a sort of half circle and then 

 the intervening space was filled up until each egg touched another. 

 In addition a few were laid a short distance away and the intervening 

 space filled up. Oviposition continued steadily until 5.20 p. m., 

 when, she stopped, turned around, felt the mass with her feet, and 

 commenced again. She stopped at 5.21 for 30 seconds and cleaned 

 the end of her abdomen. Another lot of eggs was then laid a little 

 farther off, in a long, irregular row, about five eggs wide. Oviposi- 

 tion was finally ended at 5.27.30 p. m. 



She seemed always to feel for a suitable place before ovipositing. 

 A dry spot was invariably rejected. One hundred and forty-five 

 eggs were laid from 5.15 to 5.20, about 80 eggs from 5.20 to 5.21 (this 

 seemed to be the maximum rate of oviposition), and about 117 from 

 5.21 to 5.27.30. The total number of eggs laid was 349. As there 

 were two interruptions, one at 5.20 for three seconds and one at 5.21 

 for 30 seconds, the length of time spent in oviposition was 12 min- 

 utes. The average rate at which the eggs were laid, therefore, was 

 about one every two seconds. 



The abdomen was dissected, and only one developed egg was 

 found. This was in the oviduct, showing that the oviposition was 

 normal, as all developed eggs, with this exception, had been 

 deposited. 



S. bracteatum seems to be entirely restricted to the smaller 

 streams, and its method of oviposition is similar to that of S. venus- 

 tum in all respects. It is of the same size as venustum and deposits 

 about the same number of eggs at one oviposition. 



/S. jenningsi is so closely allied to S. venustum that it is extremely 

 difficult to distinguish the egg masses of the two species, the main 

 points of difference being the smaller size of the S. jenningsi mass 

 and the somewhat smaller number of eggs that are deposited. 



The time of day generally chosen for oviposition by these five 

 species of Simulium is from about 4.30 p. m. to 5.30 p. m., or even 

 until dusk. The weather conditions most favorable seem to be sun- 

 shine and lack of wind. Females have been found ovipositing at a 

 maximum water temperature of about 95° F. The earliest records 

 of oviposition were made by the writer at Dallas, Tex. (latitude 32° 

 4' 8"), on March 25, and the latest at Spartanburg, S. C. (latitude 

 34° 50"), on November 2. 



There have been various estimates given by authors, both in 

 Europe and America, upon the number of eggs laid by Simulium-: 

 The number of eggs stated to have been laid, or probably laid at one 

 oviposition by a single female, varies from 500 to 1,500. This latter 

 figure, given for the European species 8. reptans L. (S. columba- 



