230 MOSQUITOES OF NORTH AMERICA 
that the larva can turn it completely around with the utmost ease; it feeds 
habitually with the under side of the head towards the surface of the water 
whereas the upper side of the body is towards the surface. In this customary 
feeding position, the mouth-parts are working violently ; the long fringes of the 
mouth-parts cause a constant current towards the mouth and the particles float- 
ing on the surface of the water in the neighborhood thus gradually converge to 
the mouth opening and enter the alimentary canal. The spores of alge, bits of 
dust, minute sticks, bits of cast larval skins, everything in fact which floats, 
follow this course, and, watching the larva under the microscope, they can plainly 
be seen to pass through the head into the thorax until they are obscured by the 
opaque color of the larva’s back. This is the common method of feeding when 
full grown; however, the larva will descend in the shallow water and mouth 
over the slime on pebbles at the bottom. Occasionally a fragment, too large to be 
swallowed with ease, clogs the mouth. Sometimes it enters the mouth and sticks. 
In such cases the head of the larva revolves with lightning-like rapidity until 
the top of the head is upwards, and the fragment is nearly always disgorged, 
although sometimes it is swallowed with an evident effort. 
As indicated, the larva feeds upon everything that floats. It is especially often 
found in stagnant water on which there is more or less of an algal scum; there- 
fore a very frequent food consists of algal spores, and the color of the larva is 
influenced more or less by the character of the food, green alge making it green. 
Daniels, in his African investigations found that the contents of the intestines 
of the larve are mainly vegetable matter, in some cases entirely so. “ Occasion- 
ally limbs of minute insects or crustaceans are found as well as scales of mos- 
quitoes or other insects. On watching them feeding, it is seen that all minute 
particles are drawn to the mouth, but many of them are rejected. This rejection 
is somewhat arbitrary, as a particle at first rejected is often subsequently swal- 
lowed. Amongst the bodies seen to be swallowed I have seen living minute crus- 
taceans and young larve, both of anopheles and culices, but, as a rule, living 
animal bodies either escape or are rejected.” Christophers and Stephens state 
that in their observations in Sierra Leone the food of the Anopheles larvee seemed 
to be an unicellular organism. James and Liston state that the food of Anoph- 
eles larve consists chiefly of minute water animals which abound among alge 
and other water plants. They believe that the larve can not subsist upon vege- 
table diet alone and that the duration of the larval stage depends chiefly upon the 
supply of animal food. When this is small in proportion to the number of larva, 
they state, the stronger larve kill and eat the weaker. The cause for the dis- 
crepancies in these observations undoubtedly lies, at least in part, in the fact that 
different species were under observation. Thus we have found that the tree-hole 
inhabiting larve of our Celodiazesis barberi are very largely predaceous and 
prey upon other culicid larve associated with them. The species inhabiting 
bromeliads have similar habits, as has been recorded for Anopheles cruzti by 
Peryasst. 
