1930 ] Key to the Mosquitoes of New England 243 
Several chlorine determinations 3 of water from pools 
containing larvae of A. sollicitans were made. The result^ 
of these determinations indicate that the larvae can live 
and develop in water having a chlorine content ranging 
from 400 to 2900 parts per 100,000 parts of water. Since 
the chlorine content of open sea water contained only 2000 
parts, it is evident that larvae can developed in water having 
a chlorine content greater than sea water as well as in water 
having a chlorine content considerably less than sea water. 
Several evening collections of fresh water species were 
made in the Charles River Valley. The collections made in 
late May and early June yielded A. cinerus, A. excruciens 
and A. implacabalis in about equal numbers. During July 
and August the collections contained a majority of M. per- 
turbans. Of 120 specimens taken in one collection at Need- 
ham, Mass., in August, 118 were of this species, 1 of A. punc- 
tipennis and 1 of C. pipiens. M. perturbans is a difficult mos- 
quito to control as the larvae are not free swimming but 
attached to roots and stems of various aquatic plants. The 
adults are fierce biters but fortunately are weak flyers. 
5 These determinations were made through the courtesy of the 
Massachusetts State Department of Health. 
