118 MOSQUITOES OF NORTH AMERICA 
TIME OF ACTIVITY. 
Mosquitoes are generally looked upon as nocturnal in habits but this is prob- 
ably true of only a small number of species. . Our house mosquitoes of the genus 
Culex are nocturnal. Culex quinquefasciatus, the house mosquito of the tropics, 
is strictly nocturnal and bites in complete darkness. Many species of mosquitoes 
are crepuscular, confining their activities to the twilight of evening and early 
morning. This is the case with most Anopheles and the peculiarities of some of 
the species, in this respect, are discussed in our chapter on malaria. The yellow- 
fever mosquito (Aédes calopus) is strictly diurnal; its behavior is fully dis- 
cussed in connection with yellow fever. In far northern regions the mosquitoes 
are of necessity diurnal. One of us (Knab) found that the mosquitoes of the 
Saskatchewan prairies are active throughout the day, during the hours of full 
sunlight. At evening their attacks ceased, and indeed the rapid fall of tempera- 
ture at that time puts an end to all insect activities. In the tropics, at least in 
America, a large proportion of the species of mosquitoes are strictly diurnal. 
It is true of many, if not all, the mosquitoes of the tribe Sabethini; they are 
forest inhabitants and fly about during the hours of full sunshine. The large 
and showy members of the genus Megarhinus appear to be diurnal. Lutz 
states that the males of Megarhinus solstitialis are seen flying rapidly by day. 
Knab has found a female of Megarhinus septentrionalis sucking honey from a 
flower in broad daylight. It is probable that all brilliantly colored mosquitoes 
are diurnal. The species of Aédes of our northern woods appear to be cre- 
puscular. Yet, while they are normally quiescent during full daylight, they are 
easily aroused. The presence of food, in the shape of a human being, will attract 
them, apparently from a considerable distance, as one can ascertain by remain- 
ing in one spot foratime. Aédes canadensis, Aédes stimulans and related forms 
attack viciously during midday. Aédes atropalpus will bite by day and we have 
known it to bite so late in the evening that it could no longer be seen. Knab 
found that at Winnipeg Aédes riparius came to bite in numbers during the 
middle of the day; it also bit at night in bright moonlight. Mansonia pertur- 
bans is strictly crepuscular but in dark woods will attack in the daytime. 
Different situations are sought out by the different species to pass the time of 
quiescence. Certain species which have become more or less associated with man 
seek shelter within houses or other structures. Certain species of Anopheles 
frequent cellars, out-houses and culverts, and certain species of Culex are even 
more domestic. The majority of the species of mosquitoes, however, are practi- 
cally never found in houses. They hide in the woods, on the under side of leaves, 
upon tree trunks, in hollow trees or under old logs. The prairie species hide in 
the grass. 
LONGEVITY. 
The question is frequently asked, how long a mosquito lives; the adult form 
alone being in mind. The males are very short-lived, in most cases probably a 
matter of a few days only. Their only office is to fertilize the female and this is 
usually very soon accomplished. Observations made by Knab in Saskatchewan 
