PLANTS AND MOSQUITO CONTEOL MATHESON 



Table 4. — Buttermilk Falls pool — Continued. 



425 



1 During the rest of the season there was no growth of the Chara and no breeding took place. 



From Table 4 it will be observed that the Chara was added on 

 April 9, 1928. At that time larvae of Aedes canadensis were very 

 abundant. Growth of the Cham did not begin till about May 13, 

 when the first pupae appeared. The development of the larvae 

 was undoubtedly retarded, for pupation took place in near-by pools 

 a week earlier. From June 7 till July 3 there was no breeding in this 

 pool except a few larvae on June 7. In the near-by pools Aedes 

 canadensis, Culex territans, and Culex aficalis were present in both 

 the larval and pupal stages. Early in July the near-by pools became 

 dry, and from then till September breeding took place in our experi- 

 mental pool. It should be noted, however, that early in July (July 

 3) a considerable area of decay appeared and this continued through- 

 out the season. Breeding began with the appearance of decay, and 

 this result agrees with that obtained in our experimental aquaria. 

 Another point might be noted : Aedes vexans bred in near-by pools 

 but was never found in the experimental pool. The results for 1929 

 are not very encouraging. The Chara did not apparently survive the 

 winter. It is hoped that growth may again appear in 1930. In 

 1928 the larval density of Aedes canadensis was most extraordinary. 

 A few sweeps of a small net brought in nearly 2,000 larvae, and 

 immense numbers of adults emerged. In 1929 it will be seen we 

 had difficulty in obtaining even 50 larvae. Whether this reduction in 

 breeding was due to the Chara preventing oviposition in 1928 is 

 difficult to say. Had the Chara continued to grow in 1929 we might 

 be justified in concluding that Aedes canadensis refused to oviposit 

 where Chara grows. However, as compared to near-by pools there 

 was a reduction of mosquito breeding in 1928 and an even more 

 marked reduction in 1929. The near-by pools swarmed with Aedes 



