82 
A Monograph of Culiciclae. 
of some fifteen miles. I have seen the male swarms of C. pipiens 
wafted by the air, and it is not unlikely that some of them and a 
few females may be carried gently some little distance by that 
agency, but experience and observations have shown that it is of 
unusual occurrence. But. there is plenty of evidence which goes 
to prove that when a breeze springs up the mosquitoes take 
immediate shelter, and appear again as soon as the wind drops. 
Hence a very popular and erroneous idea can be explained, 
namely, that mosquitoes are brought by the wind, carried from 
one place, that is, to another. 
The distance of flight of both Culex and Anopheles is, I 
believe, very limited. Stephens and Christophers * state that 
they must have flown a distance of from 300 to 600 yards 
in one case from their breeding-ground, and again that the flies 
congregated in the native huts and villages in the bush along the 
Sierra Leone Railway, though there were no breeding-places 
distant less than a quarter of a mile. I do not think they 
will be found to disperse more than a mile at the most, except 
under very exceptional circumstances, such as being caught in a 
violent gust of wind, which they are unlikely to be, as they take 
shelter when a breeze appears. 
Artificially they are spread by boats and railway trains. It 
is not at all an unusual thing to find mosquitoes on board ship, 
often in considerable numbers. It is especially the females that 
are found ; these creatures may be taken hundreds of miles and 
then landed, and if pregnant they may deposit their eggs. They 
may also be spread in the larval stage in ships’ tanks, especially 
formerly; by such means we can readily see how certain forms 
have spread over a large part of the globe, and we can thus 
account for such anomalies as that shown by Culex maculicrura 
and other species, which are found in widely separated localities, 
when those localities are bordering the sea. 
On land we know well that certain species have followed the 
advance of the railway. 
Skuse has shown that one common Australian species ( C . 
fatigans, sub-sp. Skusii ) has been spread by this means. Regard¬ 
ing this insect, Skusej writes as follows: “Appears to have been 
introduced into this country, judging from the accounts of old 
colonists, and is possibly a variety of C. ciliaris , Linn. It may 
have been imported from Europe in the water tanks belonging 
* Kept. Malarial Com. R.S.E., p. 10. 
f Proc. Linn. Soc. N. S. Wales, 18>9, p. 1717. 
