23 
shore 1 was practically without result so far as Anopheles larvae 
were concerned, except in two small places where this grass was 
green. Here they were found in fair quantity. On examination 
from a boat we found the outside of this ring of grass—the edge 
next open water—generally alive and containing Anopheles larvae 
in abundance. Together with another kind (Culex species), A. 
quadrimaculatus and A. punctipennis were developed. There were 
fish in the pond, but not many. 
Another pond of this company with much growth on its edges 
was examined two days later and was practically not producing. 
The effect of dead and decaying green grass on production has 
been alluded to. In addition to the above instance, in two places 
on the Coosa pond a slight permanent rise of pond level covered 
flat fields of grass: One, Japanese clover (Lespedeza), and one, 
some other kind. The grass was about 6 inches high and the water 
from 18 inches to nothing. The places were about 5 miles apart. In 
the grass in both places were “bait holes” about a foot deep, where 
people had dug for angle worms, and in them there was no grass. 
These were from 18 inches to 3 or 4 feet across. They were of 
every shape. The grass. was dead and decaying. The water had 
been up previous to the first visit 9 days for one place and 11 for 
the other; previous to the second visit 19 days. In the grass prac¬ 
tically no Anopheles larvae could be found, while in the bait holes 
they were abundant. From these bait holes many larvae of A. ci'ucians 
were obtained. Two instances of larvae killed by leaving grass in the 
bucket with them until it began to decompose occurred. Grass 
was put in to prevent the larvae from drowning, as is done in 
carrying them in a boat. 
Another plant ( Sparganium americanum , or burr reed) was 
found in three ponds in Virginia in the fall. In one pond, the only 
one properly examined, Anopheles were breeding profusely. This 
was in October and the catch was practically all A. punctipennis. 
The study of aquatic growth, as implied in the first paper on that 
subject, 2 may be an important paid of the investigation of impounded 
waters and their effect on malaria. 
1 Two men for two hours. 
2 Reprint No. 244, Public Health Reports. 
