GNATS, MIDGES, AND MOSQUITOES 241 



his hat, perpetual motion being necessary to keep them 

 at bay. Linne" testified to their extraordinary abun- 

 dance in Lapland, where smoke and grease were in his 

 time, as they probably are still, the best preventives 

 known. And in recent years, Nordenskjb'ld and others 

 have recorded meeting with enormous swarms in high 

 Arctic latitudes, in which regions, indeed, it is not only 

 Culices that exist in myriads, but other Diptera as well. 

 For instance, Dr. F. A. Walker, speaking of a visit to 

 Iceland, mentions not only that bluebottles were to be 

 found in great numbers on rotting fish everywhere, but 

 especially that the little black flies that frequent sea- 

 weed on the sand flew in multitudes on board the 

 steamer, blackening the windows of the deck-saloon. 

 Dr. Clarke, travelling in South Russia, tells a pitiful tale 

 of the persecutions to which he was subjected in passing 

 through a morass which teemed with mosquitoes to such 

 an extent that a lamp which was lit in a closed carriage 

 was soon extinguished by the swarms that flew into it. 



As may be imagined from their habits and life-history, 

 mosquitoes are not equally distributed in the countries 

 in which they occur ; in low-lying, marshy districts they 

 are most abundant, but as one recedes from the water, or 

 reaches greater elevations, they become less numerous. 

 They attack not only human beings, but also cattle, and 

 hence the proximity of the latter in places much infested 

 may sometimes give relief to men ; on the other hand, 

 they have often been noticed accompanying cattle on 

 their return from marshy pastures, clustering round 

 them, and thus becoming ultimately introduced into 

 houses. It has been said that they object to the strong 

 smell of the alligator, but if this be so, they can over- 

 come their dislike when there is a chance of a draught 

 of human blood, for Humboldt relates that, while 



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