PREDACEOUS MOSQUITO LARV# 167 
from them. It may be mentioned, however, that one of us (Knab) has seen 
agrionid larva come to the surface of the water and seize Culex larve. 
We are of the opinion that dragon flies do destroy a great many mosquitoes. 
While they show no preference for mosquitoes there seems to be, on the part of 
adult dragon flies, a marked preference for Diptera; with their great rapidity 
and activity, where mosquitoes are abundant, a considerable number must be 
destroyed by them. This must be particularly true of the large crepuscular 
species, such as Aschna, their time of activity coinciding with that of most 
mosquitoes. Mr. Nathan Banks tells us that, at College Station, Texas, he has 
observed a large dragon fly capturing flying insects in rapid succession, pre- 
sumably mosquitoes, as a great many of these were flying about at the time. Mr. 
McAtee, at Church’s Island, North Carolina, has seen a dragon fly (Hrythemis 
simplicicollis) pick Anopheles quadrimaculatus off the weather-boarding of a 
house. 
Certain ephemerid larve are active destroyers of mosquito larve. Foley and 
Yvernault found that in Algeria ephemerid larve are more efficient destroyers 
of mosquito larve than Dytiscide. 
Some very efficacious natural enemies of mosquitoes are to be found in the 
family Culicide itself. The larve of Psorophora, Megarhinus, Lutzia and 
Lesticocampa are voraciously carnivorous and even cannibalistic, while the 
larger larvee of Anopheles will attack one another and the larve of other mos- 
quitoes. In a lot of larve of Anopheles quadrimaculatus and A. punctipennis, 
kept in the laboratory in a large battery jar for study by one of us, the larve 
were noticed to disappear, and one morning nine heads were found of which the 
bodies were gone. Nothing but mosquito larvee were in the jar. One larva was 
noticed which looked as if it had two heads, but upon examination it was found 
that the body of one had been almost devoured and the survivor was eating the 
head which was all that was left of the victim. Several larve were found which 
had been half eaten. The Anopheles larve were several times seen eating the 
young Culex larve. The cannibalistic tendencies of Anopheles larve have been 
noted repeatedly by a number of writers. The larve of certain species, having 
a restricted habitat in the water in holes of trees and between the leaves of brome- 
liads, are probably entirely predaceous. 
Dr. Oswaldo Cruz, of Brazil, while on a visit to Washington, stated that in 
Rio de Janeiro Lutzia bigotii is used practically to destroy the larve of Aédes 
calopus. The Lutzia larve are introduced into receptacles in which the calopus 
breeds and soon destroy the larve of this dangerous insect. 
The habits of Psorophora in the larval stage are such as to make them very 
desirable inhabitants of stagnant pools. They have been frequently described, 
but the series of observations made at the request of one of us by Dr. W. E. 
Hinds, in the summer of 1901, and hitherto unpublished, will be of interest 
here. The following extract from Doctor Hinds’ notes, treats of the feeding 
methods of the larve: 
“ August 16. A.M. Received a lot of Psorophora ciliata larve from W. P. 
Seal, Delair, N. J. They came in a large quart bottle and with them were quite 
