POTATO INSECTS 



151 



Quebec and Prince Edward Island. While the insect is doubt- 

 less present in small numbers each year in these states, it has 

 appeared in destructive abundance only at intervals of several 

 years. This plant-louse is not confined to potatoes but also 

 injures tomato, eggplant, pea, turnip, beet, spinach, pepper, 

 asparagus, sunflower and sweet potato and has been found 

 infesting various weeds such as ground cherry, Jamestown 

 weed, ragweed, lamb's quarters and wild lettuce. It is also 

 found on canna, hollyhock, gladiolus, iris and matrimony vine. 

 It was originally described from specimens collected on the 

 pepper-vine. Solarium jasminoides, in Florida. 



The potato aphis passes the winter in the form of shining 

 brownish black eggs on the rose and possibly on other peren- 

 nials. The eggs hatch about the time the leaf-buds are opening 

 and the young aphids reach maturity on this plant. Probably 

 in the second or third generation, most of the aphids migrate 

 to the potato and other herbaceous food plants. Throughout 

 the entire growing season, only female aphids are produced 

 and these give birth to living young. Both winged and wing- 

 less females occur through- 

 out the season. In warm 

 weather a female reaches 

 maturity in ten days to 

 two weeks and may give 

 birth to more than fifty 

 young over a period of 

 about fourteen days. The 

 adult winged viviparous 

 female is about J inch, 

 and the w^ingless form 



about i inch in length (Figs. 87 and 88). Both forms are 

 usually green but pink individuals are common. The potato 

 aphis closely resembles the pea aphis but may be dis- 

 tinguished under the microscope by having the tip of the 



Fig. 87. — The winged viviparous female 

 potato aphis (X 5). 



