Insects, Diseases and Frost 275 



early in the fall previous to planting, so as to expose the pupating 

 grubs to the winter. 



Hogs, chickens and turkeys are efficient destroyers of grubs if al- 

 lowed to follow in the furrow while plowing. When a plant is infested, 

 there is no remedy but to dig down beside the crown and find the 

 grub. This is not practicable commercially. Applications of kainit 

 are not effective. Plants of a valuable novelty may be WTapped in 

 wire fly screening when set; the roots grow through the netting, 

 but the grub cannot get to the crown. 



Root-louse {Aphis forbesi). 



The presence of this insect is indicated by spots where all the 

 plants have been killed, and the adjoining plants look unthrifty. 



FiQ. 21. — Root-louse. On left, the stem mother ; center, viviparous fe- 

 male of late summer and fall ; right, the male. 



Sometimes this is mistaken for winter injury. The plants dry out, 

 the fruit is small and fails to ripen ; numerous ants around the plants 

 are another indication. Dark green, bluish or blackish lice will be 

 found clustered on the roots and crowns of unhealthy plants. This 

 insect is widely distributed in the states east of the Rocky Mountains, 

 but is most destructive in Illinois, Ohio, Delaware and Maryland. 

 It does more damage on sandy soil than on heavy soil. The insects 

 are very abundant for several years, then disappear for a time. 



Numerous small shining black eggs about one thirty-fifth of an 

 inch long are laid in the fall by the last generation of that year, upon 

 the stem and midribs of the greenest leaves. In the spring they 

 hatch into wingless females, which give birth to hving young through- 

 out the season. In twelve to fifteen days the aphids are full grown 

 and begin to bear young. The small, brown, cornfield ants carry 



