Artificial Distribution of Mosquitoes. 
81 
ALTITUDE NO SAFEGUARD AGAINST MOSQUITOES, 
Although mosquitoes are found in greatest numbers in low- 
lying, swampy districts, they are nevertheless found at great 
elevations in considerable numbers. Altitude is not a safeguard 
against Culex and Anopheles , and therefore not a safeguard 
against fever. Koch found mosquitoes at 3,000 feet in fever 
communities in Java. Sir William MacGregor tells us they 
attacked his party in camp on Mount Scratchley at 1000 feet, 
and that they were very troublesome at 5,000 to 6,000 feet. 
From India I have a note (accompanied by specimens 
( C . nigripes , Zett. ?)) stating that the enclosed mosquitoes are most 
annoying in the Himalayas at an altitude of 13,000 feet : so 
that, if I am correct in the identity of the remains sent me from 
India, we have a single species with a vertical distribution of 
13,000 feet, for we find this species at sea-level in Scandinavia. 
HOW MOSQUITOES ARE DISTRIBUTED FROM 
PLACE TO PLACE. 
The dispersal of Culicidae takes place chiefly by artificial 
agencies, which alone can account for the extensive distribution 
of many of the species. Naturally they can be spread by the 
wind, but from observations I have made I do not consider that 
they are so to any extent, even for short distances. It is useless, 
I have found, to look for specimens on the wing when there is 
any breeze; they are then found sheltering themselves under 
leaves, holding on to twigs and in other places equally sheltered, 
so that if these delicate creatures are so dispersed, it is of chance 
occurrence and undoubtedly rarely takes place. By dispersed I 
mean for some considerable distance, for they are no doubt now 
and then blown by light breezes some little way from their 
breeding-pools. With regard to this point, Dr. H. T. Fernald 
states that at Cold Spring Harbour, Long Island, with a north 
breeze, there are no mosquitoes. With a south breeze, on the 
other hand, they are often very troublesome, especially after a 
prolonged gentle wind of five or more hours’ duration. There 
are no pools in the centre of the Island, and the mosquitoes are 
supposed to have been carried from the south shore, a distance 
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