134 MOSQUITOES OF NORTH AMERICA 



" It took us but little time to rush over the gangway and seek safety from our 

 pursuers within the precincts of the steamboat. But they were not to be 

 baffled easily : they came in after us in millions ; like Bishop Haddo's rats, they 

 came ' in at the windows and in at the doors/ until in a very short space of time 

 the interior of the boat became perfectly black with insects. Attracted by the 

 light they flocked into the saloon, covering walls and ceiling in one dark mass." 



Mr. L. A. Fuertes, the well-known ornithologist, tells us that on the western 

 plains in Saskatchewan, at Maple Creek along the line of the Canadian Pacific 

 Eailroad, in June, 1908, mosquitoes were so numerous and were such a pest 

 that, unless there was sufficient wind blowing to keep them down, it was almost 

 insupportable, and the sheep herders and the laborers on the railroads daily 

 were forced to wear head-nets and gloves in the pursuit of their occupations. 

 On nights when there was a slight wind, the cattle would trot up the breeze and 

 could be vnih certainty found at the farthest fence that they could get to. 



Mr. H. W. Henshaw, of the Biological Survey, U. S. Department of Agri- 

 culture, relates the following : 



" While in camp on the western shores of Kern Lake, California, in the fall 

 of 1875, about 4 o'clock in the afternoon, the light breeze which had been blow- 

 ing steadily all day suddenly ceased. Within a few moments the air was so 

 filled with hosts of mosquitoes which came from the swampy land adjoining 

 the lake that it was impossible to talk without dozens of the insects entering the 

 mouth and nostrils. The mules which were picketed out on grass became 

 frantic, and it was only with the utmost difficulty they could be restrained — in 

 fact, so persistent were the attacks of the insects that the camp equipage was 

 immediately packed on the animals and the place vacated." 



When mosquitoes appear in such enormous numbers this is due to the simul- 

 taneous development of immense numbers of larvae. In cases of excessive 

 abundance the species concerned are nearly always single brooded. As the best 

 example we can give the northern species which must develop their single brood 

 in the early spring from the water of the melting snows. jSTaturally, in these 

 cases, there is a very evident relation between the amount of snow and the num- 

 ber of mosquitoes in different seasons. 



It was until recently believed that mosquitoes reached such enormous abun- 

 dance by rapid progression through a series of generations. Careful observa- 

 tion, however, shows that those species which breed continuously throughout the 

 summer, while they increase somewhat in numbers as the season advances, never 

 reach the enormous numbers of the single-brooded species. It has been assumed 

 by some writers that an almost unlimited number of mosquitoes can be bred 

 from a single rain-water barrel. Lugger has attempted to estimate the actual 

 number of mosquitoes (eggs, larvge and pupae) present at one time in such a 

 barrel, as follows : 



" July 6th, 1896, the water in one barrel was filtered. It contained 35 grams 

 of mosquitoes, each gram, by count, numbering 217, hence 35x217 = 7,595 

 larvae and pupae. Besides this 32 egg-masses, each containing on an average 302 

 eggs, were found, which would hatch into 302x32 = 9,664 mosquitoes. Total 

 number of eggs, larvae and pupae 17,259. July 22d, 1896, by a similar process, 

 19,110 mosquitoes were counted." 



