INSECTS INJURIOUS TO POTATOES AND TOMATOES 293 



the Atlantic States in 1874. ' Though slow to be introduced into 

 some few sections of the country, it is safe to assert that this pest 

 may to-day be found almost wherever the potato is grown in the 

 United States or southern Canada. 



Life History. During October the beetles enter the earth and 

 there hibernate till the warm sunshine of April or May brings 

 them forth. As soon as the young plants appear, the female 

 beetles deposit their yellow eggs upon the under side of the leaves 

 near the tips, each female laying an average of about five hundred 

 eggs during the course of a month. Meanwhile the beetles have 

 done considerable damage by eating the young and tender plants. 

 In about a week there hatch a horde of 

 very small but very hungry larvae, which 

 fairly gorge themselves with potato- 

 foliage and increase in size with astonish- 

 ing rapidity. In two and a half to three 

 weeks, after having eaten an amount of 

 food out of all proportion to their size, the 

 larvae become full grown, and enter the 

 earth, where they form smooth, oval 

 cells, and transform to pupae. In a week 

 or two the adult beetles emerge from 



the pupal skins and after feeding for a couple of weeks, deposit 

 eggs for a second generation, which develops in the same way, 

 and tlie beetles from which hibernate as already described. 

 Throughout the territory where the beetles are most injurious 

 there are two generations a year, but further south there is evi- 

 dence of at least a partial, if not complete, third generation, and 

 in the northern range of the species there is but one generation 

 a year. 



Natural Enemies. One of the chief agencies to prevent the 

 excessive multiplication of this pest is the weather. Thus, Pro- 

 fessor Otto Lugger records that in Minnesota, late in the fall 

 of 1894, the beetles were lured from their winter quarters by a 

 few warm days, and most of them subsequently perished from 

 hunger or frost. In addition to this during the late summer of 



FIG. 213.- -a, beak of pre- 

 daceous bug; b, Podi- 

 sus spinosus Dall.; c, 

 beak of plant-feeding 

 bug. (After Riley.) 



