FLOWERS ON WATER SIDE AND SURFACE 125 



the culture of water-lilies can make shift with 

 casks sawn through the middle. In temperate 

 countries no winter protection is necessary, but 

 not otherwise. As protection against frost Latour- 

 Marliac recommends that a trench be made at a 

 depth equal to one-third the height of the tubs, 

 which are then placed in it and banked up to the 

 edges with the soil dug out. One would hardly 

 believe what a charming effect can be produced 

 by tubs arranged in this way. 



Of pests we are sometimes troubled with water- 

 rats, but M. Latour - Marliac complains of two 

 kinds of larvas, the one black and the other white, 

 produced by certain small yellowish-white butter- 

 flies which deposit their eggs on the floating leaves. 

 Their larvas, at first almost invisible, develop to 

 about the thickness of a wheat straw and devour 

 the leaves of the water-lilies during the night. 

 They are very clever in hiding themselves during 

 the day, laying fragments of the leaves on their 

 bodies and covering themselves with bits of lemna 

 or azoUa. These pests may be destroyed by 

 pouring on the surface of the water some drops 

 of a mixture of three-quarters colza oil to one 

 quart of paraffin, a sufficient dose to poison them 

 without injuring the plants. 



