170 MOSQUITOES OF NORTH AMERICA 
these larve prey upon the small red worms known as Tubifex or upon the larvae 
of Chironomus. One of us (Knab) found that larve of Tanypus dyari, acci- 
dentally introduced into breeding-jars, were very destructive to mosquito larve. 
A remarkable case is that of an adult fly preying upon mosquito larve. J. 
Mitford Atkinson gives an account of Lispa sinensis Schiner, an Anthomyid fly, 
which at Kennedy Town, Hongkong, was seen to be eating the larvee of mosqui- 
toes. On stirring up the stagnant water crowds of larve were disturbed. “The 
flies pounced down upon them and rapidly devoured larve almost as long as 
their own bodies; at times they would fly away with the larve in their mouths.” 
The flies were determined by Mr. E. E. Austen. 
Dr. Paul Osterhout, of Bocas del Toro, Panama, has recently observed flies 
of the family Dolichopodide, well known for their predaceous habits, to attack 
mosquito larva in a similar manner. We quote the following from his letter to 
the Surgeon-General of the Public Health and Marine Hospital Service: “A 
short time ago, in passing through the outskirts of the town, I saw a large 
swarm of small flies seemingly very much occupied about a small pool of water 
standing in a wagon track (the track had been undisturbed for several days 
from the appearance), so I stooped to see what the commotion was about and I 
saw hundreds of these small flies and thousands of mosquito larve. J remained 
for some time watching the commotion and saw several of the flies catch the 
larve and drag them to the dry earth and devour them.” 
D’Emerez de Charmoy, the Director of the Museum in the Island of Mauri- 
tius, has made a study of the natural enemies of the malarial mosquitoes in 
Mauritius. He has drawn up the following interesting table showing at a glance 
the results of a series of experiments which he made to determine the relative 
effectiveness of certain species of insects and of a small fish in destroying mos- 
quito larve : 
Least 
Numberof ; 
Number | larvee of eerie 7 Pe 
Enemies. of individ-/ Anopheles/o7, SoC ..| Beal 
uals. | in the re- [Ses lervwe| of larvre 
ceptacle. hour: 5 
Hours. 
Bt ie al i piensnencs 3 By 16 a ouiek co GL ae 
er desjardinst.......... 2) eee ndifferent destruction. 
Hh, daticus exclamationis.... 1 ee 3 2 Indifferent destruction. 
a ae. aaa aris ql ka % so Capture with difficulty. 
Ranatra larvie...........0s 8 30 48 
Larvee of Culex tigripes..... 4 12 a 48 
Cyprin doré (8% in. long).... 1 30 15 2 Quick destruction. 
Various adult insects have been found to prey upon adult mosquitoes. Dragon 
flies have already been mentioned and there is no doubt that mosquitoes furnish 
their quota of the food captured by these insects while on the wing. In this 
connection the crepuscular habits of certain species of dragon flies should be 
noted. 
In the Diptera the Empidide are well known to be predaceous, capturing other 
insects upon the wing. Wahlberg, in an interesting paper on the mosquitoes of 
