CHAPTER XIII 



INSECTS AFFECTING TRUCK CROPS AND THE VEGE- 

 TABLE GARDEN 



IT is difficult to sharply separate truck crops from field crops. 

 It will be noticed that corn insects are treated in the preceding 

 chapter on insects affecting field crops. Insects attacking onions, 

 tobacco, turnips, and beets are likewise considered there. Irish 

 potato and sweet potato insects are treated in the present chapter. 



Potato Insects 



The Colorado Potato Beetle. This well-known beetle (Lep- 

 tinotarsa decemlineata Say) and its larvae are so familiar that they 

 need no description. The adult beetles hibernate below the surface 

 of the ground, appearing on the plants in the spring, soon after 

 reaching the potato plants. They lay their eggs on the under sides 

 of the leaves. These eggs hatch in something less than a week, 

 the larvae passing through four stages and requiring about three 

 weeks to complete their growth. They pupate below the surface 

 of the soil and occasionally upon the leaves. The pupal stage 

 requires from one to two weeks. The egg-laying period lasts about 

 five weeks, and the broods consequently overlap each other. 

 We therefore find all stages upon the plant at the same time 

 (Fig. 236) . The female beetle lays from five hundred to one thou- 

 sand eggs, these eggs being placed in masses of from nine to thirty- 

 five eggs each. 



It may be mentioned here that the so-called "old-fashioned 

 potato beetle" (Epicauta sp.) sometimes occurs on potatoes. 



Control. The young larvae can be killed by a spray of one 

 pound of arsenate of lead in twenty-five gallons of water. As 

 they get older, however, it is more difficult to poison them, and the 

 adults are particularly resistant. Therefore, in order to make the 

 poison more effective, it is advised to use one pound of Paris 

 green, two pounds of arsenate of lead, and fifty gallons of water 

 for all forms. Arsenate of lead is preferable to Paris green alone, 

 since potato foliage is susceptible to injury. Several applications 

 of the spray during the season may be necessary ; it should be used 

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