APPLE INSECTS 



181 



Fig. 178. — The 

 apple leaf-hopper, 

 adult (X 11). 



and celery ; more than a dozen other plants, including weeds 

 grasses, grains and shade trees, are also among its food-plants 

 Puncturing the tissues with their tiny beaks, 

 these leaf-hoppers suck the juice, giving the 

 leaves a peculiar, mottled, yellowish appear- 

 ance and finally causing them to curl. 

 Nursery trees, especially apples, are often 

 seriously injured, the insects working mostly 

 on the undersides of the leaves. The adult 

 insects are about ^ of an inch long and of a 

 pale yellowish-green color with 6 or 8 distin- 

 guishing white spots on the front margin of 

 the pronotum (Fig. 178). When disturbed 

 the pale green young or nymphs run in all 

 directions, but the adults can jump quickly 

 and fly away. The apple leaf-hopper hibernates in both the 

 egg and the adult stages. The winter eggs are deposited in the 

 bark of the smaller branches just below the epidermis, two- 

 year-old wood being most often selected. The position of the 

 egg is indicated by a low blister-like eleva- 

 tion of the bark about ^q of an inch in 

 length and half as wide. The egg itself is 

 white, elongate, slightly curved and is 

 about 4V of an inch in length. The winter 

 eggs hatch soon after the leaf buds burst 

 in the spring and the hibernating adults 

 appear on the trees about the same time. 

 The young hoppers pass through five 

 nymphal stages and acquire wings at the 

 fifth molt (Fig. 179), about a month after 

 hatching. The summer eggs are not in- 

 serted in the bark, })ut in the petiole and 

 larger veins of the leaves. There are four generations annually 

 in the latitude of Iowa. The first generation works on the 



Fig. 179. — Fifth 

 stage nymph of the 

 apple leaf-hopper. En- 

 larged. 



