THE HOMOPTERA 193 



solution of whale-oil soap 1 Ib. in 8 gal. of water, or dissolving a bar of 

 common laundry soap in 6 to 8 gal. of water for the purpose. 



The Rose Leaf hopper (Empoa rosce L.). This European insect is now 

 present practically everywhere in the United States and is also found 

 in Nova Scotia, Ontario and British Columbia. It is a general feeder 

 and will probably attack most plants of the family Rosacese, but appears 

 to be particularly injurious to the rose and apple. The adult is almost 

 as large as the apple leafhopper and is creamy white to light yellow. It 

 lays its eggs during the fall in the bark of rose bushes, apple trees, berry 

 canes and other plants and there they remain until spring, when they 

 hatch. The nymphs suck the sap from the under side of the leaves of 

 the plants, producing a mottled appearance, and as the injury increases 

 the leaves may turn yellow and dry up, but they do not curl. There 

 are two generations of this insect a year, the eggs for the second genera- 

 tion being laid in July. Most of the wintering eggs are deposited in rose 

 stems. 



Control. This insect is rarely of importance as an apple pest but 

 rose bushes often suffer by the loss of sap and the impossibility of their 

 injured leaves performing their proper functions. Spraying infested 

 plants with nicotine sulfate as for the apple leafhoppers, as soon as the 

 nymphs are observed, is usually sufficient to prevent further injury. 



Many other leafhoppers are at times serious pests. The beet leaf- 

 hopper in the Western States in addition to its injury to the plants by 

 feeding, transmits a " curly leaf disease" and the grape leafhopper is 

 sometimes so abundant that grape leaves in vineyards are turned brown 

 and much injured. The six-spotted leafhopper attacks some grains and 

 grasses, and other species generally of slight importance, at times assume 

 prominence. In general, nicotine sulfate prepared as indicated above, 

 is an effective control material for these insects wherever conditions 

 permit its use. 



Family Chermidae. The Jumping Plant-lice as the members of this family 

 are usually called, are very small insects which feed on various plants but are 

 rarely abundant enough to become of economic importance. One exception 

 to this occurs and a consideration of that species will also give something of a 

 general idea of the insects of the group as a whole. 



The Pear Psylla (Psyllia pyricola Forst.). The Pear Psylla is a European 

 pear pest which seems to have reached this country about 1832 and is now 

 present everywhere in the eastern United States at least as far south as Virginia 

 and west to the Mississippi River, and has also been reported (perhaps errone- 

 ously) from California. Where it is abundant it is very injurious, seriously 

 checking the growth of the tree, so that many of the leaves turn yellow and drop 

 off, as does much of the young fruit, while.the entire vitality of the tree is reduced 

 and it makes little or no growth. 



The adult (Fig. 184) is about a tenth of an inch long, the body black with 

 reddish markings, and long antennae are present. Except for this last feature 



13 



