148 MOSQUITOES OF NORTH AMERICA 
An important fact to be considered is the habitat peculiar to each species or 
group of species and this, of course, is intimately connected with the feeding 
habits. Thus certain species are found only in rain puddles charged with mud. 
Other species thrive in pools and ditches full of dead leaves and other vegetable 
debris, or in sphagnum swamps. The Anopheles larve are surface feeders and 
often occur where there is a slight flow of clear water which favors the growth of 
the alge upon which they feed. Some species of Anopheles thrive, however, in 
other situations. We have found the larve of certain species plentiful in tem- 
porary rain puddles which showed no trace of alge. Other species of Anopheles 
breed in the water in holes of trees and between the leaves of bromeliaceous 
plants. Tree-holes form the habitat of the larve of a number of species of mos- 
quitoes which breed nowhere else. Plate x, fig. 3, shows such a mosquito breed- 
ing tree-hole. Others, while strongly attached to tree-holes, show a certain 
degree of adaptability, breeding in rock-pools, tubs and barrels under suitable 
conditions. It is to be supposed that the food conditions along with the general 
environment are here the determining factors. 
In the tropics the larve of many species live in the water or liquid held by 
various plants which are modified for this purpose. While this water or liquid 
furnishes a breeding-place for mosquitoes and other insects it fulfills a more or 
less important function in the economy of the plant. Thus in many Brome- 
liaceze water collects at the bases of the leaves and this water serves as a barrier 
to prevent the access of ants and other injurious insects to the flowers. With 
certain tropical American species of Heliconia and Calathea the flower bracts 
form a receptacle whose office is probably primarily to protect the flower itself. 
In the case of Calathea at least the liquid held by the bracts is dark and thick 
and is probably secreted by the plant itself. In America certain species of 
Sarracenia and in the East Indies certain Nepenthes have leaves peculiarly 
modified to hold liquid. These leaves act as traps to most insects, which, having 
entered, can not escape and are finally drowned. Their decomposition is sup- 
posed to furnish food for the plant. In our common pitcher plant (Sarracenia 
purpurea) the leaf cups are open and have a broad lip to catch the rain-water 
and dew. In the case of Nepenthes the leaf cup has a lid which projects over its 
mouth and which, while it does not close it, prevents water from entering; the 
cups are filled with a viscous liquid secreted by the plant itself. All these plants 
support mosquitoes peculiar to themselves. In tropical America the many 
species of the tribe Sabethini inhabit almost exclusively such plants. Certain 
species of Culex are peculiar to the bromeliads, as are also a few species of 
Anopheles and Megarhinus. Most of these larve are scavengers and feed upon 
the remains of insects that have been trapped by the plants. A few are pre- 
daceous and prey upon the larve of the other species. Such are Lesticocampa 
and certain species of Megarhinus. A remarkable fact is that even these canni- 
balistic forms are confined to a single plant, each species of plant thus having 
a fauna peculiar to itself. The only case in our temperate zone, of such close 
adaptation to a single plant, is the pitcher-plant mosquito, Wyeomyia smithit. 
Our plates iv, v and vi show water-bearing plants known to harbor mosquito 
larve and other aquatic insects in the American tropics. 
