EXTRAORDINARY ABUNDANCE 135 
At first sight these figures appear overwhelming; in fact, however, they are 
insignificant. It must be remembered that the mosquitoes in a barrel are of all 
stages, from egg to pupa, and that only a very small proportion reach maturity 
each day. The greater the number of larvae present in a barrel the slower will 
be their development, on account of the limited food supply, and it is by no means 
certain that anywhere near all the larve in such a barrel ever attain the adult 
state. Moreover the above figures appear exaggerated; thus counts by others 
show an average, in some cases of about 200 eggs, in other cases less, in the egg- 
masses of the common species.* Experience has shown us that the amount of 
annoyance to the inhabitants of a house, from the mosquitoes of a single well- 
stocked rain-water barrel, is not so great as would be thought, and beyond a very 
limited area there is no perceptible effect. 
One of us (Knab) has observed a case of extraordinary abundance of Culex 
pipiens at Urbana, Illinois, due to unusual breeding facilities. A creek in the 
vicinity of the town is practically stagnant in the late summer. At a certain 
point this creek received the waste from an abattoir and, as a result, for some 
distance was so charged with decomposing animal matter that no fish could 
live in it. In this strongly polluted water immense numbers of Culex larve 
throve. They were so numerous that their breathing-tubes produced the appear- 
ance of a scum upon the surface of the water. The imagos covered the foliage 
of the trees and bushes along the stream ; they were present in millions and they 
continued to reproduce until cut off by cold weather. Yet their presence was 
not felt at even a short distance, and very few of these mosquitoes found their 
way into the town—perhaps a mile away. 
Thus it will be seen that great mosquito abundance in any region is not the 
result of the accumulated products of successive generations but the practically 
simultaneous development of large numbers over a wide area. 
MOSQUITOES IN THE FAR NORTH. 
As is well known, mosquitoes abound, for a short season, even in arctic regions. 
The writers have made a number of efforts to secure good mosquito material 
from the arctic regions, but very few specimens have been sent in, so it has been 
impossible to study the species, As a matter of fact, mosquitoes seem to be even 
more numerous in individuals in the far north than they are in certain parts of 
the tropics; in the tropics, on the other hand, there is a very much greater 
variety and very many more species. Many accounts of arctic exploration and 
of travels in the far north dwell upon the extraordinary abundance and ferocity 
of the mosquitoes during the short arctic summer. Such accounts are merely 
a part of the record of the travellers’ experiences and are almost wholly prompted 
by the discomforts endured. They contribute practically nothing beyond the 
facts which were forced upon the travellers—abundance and ferocity. 
That mosquitoes should develop in such extraordinary numbers in the arctic 
regions seems remarkable when we consider the extreme brevity of the summer 
season. In fact, however, it is this brevity of the summer which brings about 
* Weber, S. E.: Entom. News, v. 17, pp. 214-217; Davis, J. J.: Ibid., p. 369. 
