154 MANUAL OF VEaETABLE-aAllDEN INSECTS 



of the potato aphis, careful watch should he kept of the plants 

 and when the lice begin to appear in any abundance, steps should 

 be taken to destroy them before the vines become stunted. 



The potato aphis is often aided in its destructive work on 

 potato and other garden plants by the spinach aphis, for a 

 discussion of which see page 105. 



References 



Maine Affr. Kxp. Sta. Bull. 147. 1<)07. 

 Maino Ast- Kxp. Sta. Bull. 1<)(). 1<)11. 

 Maine A^^r. Exp. Sta. Bull. 242. 1915. 

 Ohio A^T. Exp. Sta. Bull. ;U7. 1917. 



The Apple Leaftioppek 



Empoasca mnli Lo Baron 



The well-known apple leafhopper, a trou})lcs()nic ])cst on 

 apple nursery stock, often breeds during the summer on potato 

 vines. The insect j)asses the winter in the egg stage on the 

 a})j)le and the first brood of nymphs (levcloi)s on this plant, 

 reaching maturity about a month after hatching. Some of 

 the adults of the second and later broods migrate to potato 

 and there insert their small, whitish, elongate, slightly curved 

 eggs about 4V i'^^'^^ i'^ length, in the tender parts of the potato 

 vines. The eggs hatch in a few days and the young nymphs, 

 in company with the adidts already ])rcsent on the vines, feed 

 on the underside of the leaves, causing them to curl and stunt- 

 ing the tender growing tips. The injury is most noticeable 

 in periods of drought. The young hoppers pass through five 

 nymphal stages, accpiiring wings at the fifth molt. The 

 nymphs arc j)alc greenish and in the last stage are about y^ 

 inch in length. The adult Icafhoppers are about I inch long and 

 of a pale yellowish green color, with six or eight distinguishing 

 white si)()ts on the front margin of the pronotum (Fig. 89). 



