ENEMIES AND FRIENDS 185 



sary. If this operation is repeated each year, 

 the crawfish never become a source of serious 

 danger to the well-being of the water garden. 



In other artificial ponds none of the above 

 mentioned enemies, algae perhaps excepted, 

 are liable to become serious. But there are 

 others, particularly those belonging to the 

 insect world, which may cause trouble in any 

 kind of pond. One of these is the leaf-miner, 

 the larva of which channels through the 

 leaf between the upper and lower skins. It 

 may be destroyed by spraying with kerosene 

 emulsion made according to the standard 

 formula. This is best done in the evening 

 after the flowers are closed. Unhappily, the 

 same method cannot be used to combat the 

 leaf-cutter who cuts off portions of the leaves 

 and makes a sort of tent of them, inside of 

 which it moves about. Later in the season, 

 especially, this larva can do much damage. 

 The remedies suggested are lamp-traps and 

 picking off by hand. Dragonflies and frogs are 

 their natural enemies. The latter should 

 be encouraged by every means. 



