HIBERN ATION 119 
upon édes spencerti, under unusually favorable conditions, indicate a length of 
life of from two to three weeks for the males of that species. Indications are that 
only a very few of the males live to the maximum of three weeks. It was possible 
to gauge the length of life of these males thus accurately because this species has 
but a single brood and all the adults issued within, at the most, a week. 
The length of life of the female exceeds that of the male but differs with the 
species and with circumstances. In temperate regions certain species hibernate 
and these probably live longest as their activities are divided by an intervening 
long period of quiescence. In these cases the length of the winter will determine 
the longevity of the mosquito and we must look upon certain species of Culiseta 
and Anopheles which occur far to the north as living longest. 
There is a correlation between the habits of oviposition and length of life. 
Members of the genera Culex, Culiseta, Lutzia and Uranotenia deposit all their 
eggs at one time in a mass and death ensues immediately or soon after the eggs 
are laid. The females of these genera may be said to be short-lived, the species 
being perpetuated through a rapid succession of broods during the warm months. 
In Aédes, where the eggs are deposited in small lots, at intervals, the female 
lives much longer, in many cases several months. Accurate data can not often 
be had on account of disturbing factors and we must rely largely upon our 
general knowledge of the species. In a few cases, however, we have experimental 
or other evidence which is conclusive. Aédes calopus has been a frequent subject 
of experiment and females have been kept in captivity as long as 154 days, al- 
though this appears to be far in excess of the normal span of life. Observations 
by Knab, made in western Massachusetts in 1903, indicate that the females of 
certain species of A édes live at least three months. He found that Aédes stimu- 
lans, A. fitchit and A. abfitchit have but a single brood which develops early in 
the spring. The data for the three species coincide so closely that they may be 
considered together. The earliest capture (as appears from preserved speci- 
mens) of a female was April 29; they continued abundant and troublesome 
through May and June but showed some decrease during August. We have 
specimens captured as late as September 12. 
HIBERNATION AND /ESTIVATION. 
With the majority of the species of mosquitoes the unfavorable season is 
passed in the egg state. Certain genera, however, pass the winter, and in cer- 
tain tropical regions the dry season, in the adult state. In such cases it is only 
the female that survives, having been previously fertilized, to deposit her eggs 
at the beginning of another season. Theobald states that the male of Culiseta 
annulatus hibernates in England but this record stands quite alone. It is certain 
that at least in the genera Culex and Anopheles no males survive the winter. 
The hibernating females seek shelter with the approach of cold weather and at 
this time they show no inclination to feed. Those species more or less associated 
with man take advantage of the shelter of cellars, stables, sheds and other build- 
ings, the darkest ones apparently being the most favored. They have also been 
found hibernating in caves. Other species retire to hollows in trees, crevices in 
