12 
that he has seen /'undulus heteroclitus jump out of the water to 
catch mosquitoes, green-head flies and Hphydra. 
EFFICIENCY oF FunpuLUS Herprociitrus As A Mosquito 
EXTERMINATOR 
In the laboratory many experiments were performed with Mun- 
duli of all ages to determine how many mosquito larve they will 
take at one meal. Out of about 30 experiments, the average number 
was 25. After eating from 20 to 30 larve, a Mundulus apparently 
needs time to digest, as it rarely begins eating again for at least two 
hours. 
The best record of feeding for a medium-sized Pundulus was 15 
mosquito larva of the second moult in 5 minutes. 
In order to determine the capacity of killifishes under laboratory - 
conditions, when fed 10 larvee at a time during a period of about & 
hours of the day, experiments were performed as follows. 
Two large killifishes (about 7 cm, or 2.75 inches) two medium- 
sized killifishes, (about 5 em, or 2 inches) and two small killifishes 
(about 3 cm, or 1.20 inches) were selected as suitable for the experi- 
ments. All were apparently in perfect health and among the most 
vigorous of the lot collected at this time. Six aquarium jars, each 
12 inches in diameter and 4 inches in height were prepared with salt 
water previously boiled and diluted to 6 per cent salt. Into each 
of the jars a fish was placed and allowed to accustom itself to its sur- 
roundings for a period of about 12 hours. A mixture of mosquito 
larvee of the species Aedes sollicitans Wlk., Aedes cantator Coq: and 
Culex salinarius was carefully sorted into larve of approximately the 
same age and size, and held in readiness for the feeding experiment. 
Beginning on the fourth of August, 1915, Mr. F. E. Mehrhof 
began feeding the larve to the fish, continuing his experiment for a 
period of four days. ‘The plan of the experiment was to observe the 
fish at intervals of 30 minutes and supply them with larve of the 
second moult in groups of 10. When more than one larva was left in 
the jar the fish was not given a new lot of 10. The presence of larvx 
which had passed through the body of the fish as excrement was ig- 
nored. 
The graphs which follow show the average consumption of each 
fish for the period of four days. 
