Smithsonian Report. 1931. — Matheson 



Plate 4 



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1. A series of aquaria stocked with Chara frngi/is to test the effect of this plant on mosquito 

 larvae and on oviposition by the adults 



2. A pond near Ithaca which for several years has been completely covered with Lemna sp. 

 In 192y the entire surface became suddenly covered with WoUfla punctata, a plant closely 

 related to Lemna. Mosquito breeding has rarely been observed in thi.s pool and then only 

 scattered larvae 



