LEAF-MINERS INJURING THE FOLIAGE 189 
black. It oecurs 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 susceptible to burning. 
The Spinach Leaf-miner (Pegomya vicina Lintn.) 
Whitish mines are made .n the leaves of beets and spinach by a 
maggot which burrows within 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 on 
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 
Fig. 236.— Work of the Spinach Leaf-miner. 
also in lamb’s-quarters ee 
SO . quarters, Original. 
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 (Phthorimea operculella 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 larvee 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 larve as they start their new mines. Horse nettles should 
