LEAF-MINERS INJURING THE FOLIAGE 



189 



black. It occurs principally in the South, and there are several 

 generations annually. The pest may easily be checked by apply- 

 ing arsenate of lead or Paris green, taking care not to use too heavy 

 a dose, since beans are suscei)tible to burning. 



The Spinach Leaf-miner {Pcgomya vicina Lintn.) 



Whitish mines are matl' n the leaves of beets and spinach by a 

 maggot which burrows wil'.iin the tissues. Several of these mines are 

 seen often in a single 

 leaf. The maggot is 

 the larval stage of a 

 gray, two-winged fly, 

 which lays its eggs mi 

 the under side of the 

 leaf. The pupal stage 

 is passed in or on the 

 ground. There are 

 several generations 

 annually. 



Since this pest lives 

 also in lamb's-quarters, 

 thorough destruction 

 of this weed will help in control. Where practicable, infested leaves 

 should be removed from the plants and destroyed. No successful 

 sprays have been devised. 



The Tobacco Leaf-miner {Phthorimoea operculclla Zell.) 



This pest is commonly known as the '' split- worm." It is a very 

 small larva, and injures the older leaves of growing tobacco by mining 

 within the leaf tissues, causing small blotches. The larva3 move more 

 or less from place to place, one worm making several mines. There 

 are several generations in a single season. The native food plant 

 is horse nettle. 



Spraying or dusting with arsenate of lead or Paris green will kill 

 many larvae as they start their new mines. Horse nettles should 



Fig. 236. — Work of the Spinach Leaf-miner. 



Original. 



