10 BULLETIN 329, U. 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 319. 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. hracteatum 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 S. reptans L. (S. columba- 
