176 The Potato 



legs b}'^ which they crawl about until they find a grass- 

 hopper's egg mass, upon which they feed. They then molt, 

 their legs becoming rudimentary. As helpless grubs they 

 complete the remainder of their lar^'al stage surrounded 

 by an abundance of food. There is one brood a year. 



Control. — If potatoes are carefully sprayed for the 

 Colorado potato-beetle and flea-beetle, there will be little 

 danger from the attack of these insects. Sometimes, 

 however, they appear in large numbers and should be im- 

 mediately killed by additional applications of arsenical 

 poisons. 



The three-lined leaf -beetle {Lema trilineata) 



These leaf-beetles are leaf-eating insects. Both the 

 adults and larvse of this insect feed on potato leaves. This 

 beetle is smaller and more elongated than the Colorado 

 potato beetle and has only three black lines on a yellow 

 ground color. The larvse are distinguished by having their 

 backs covered with their own excrement. 



The adults hibernate over winter and come out in the 

 spring, laying their eggs on the underside of the potato 

 leaves along the veins. There are two broods a year ; the 

 larvse of the first brood appear in June and those of the 

 second brood in August. The adults of the second brood 

 go into the ground to hibernate over winter. 



Control. — This insect is controlled in exactly the same 

 way as the blister beetles. 



Tortoise-beetles (Cassida and Coptocycla) 



Tortoise-beetles are leaf-eating insects. The insects 

 of these genera are of minor importance, but may do some 

 damage in unsprayed fields. Their oval shape and flaring 



