THE HOMOPTERA 



191 



in the most southerly portions, which injures the twigs of fruit trees by its egg 

 punctures made in the fall. Two rows of punctures are made, nearly parallel to 

 each other, the two rather resembling parenthesis marks, 

 and in each a number of eggs is laid which hatch the follow- 

 ing spring. Injury caused by the feeding of the nymphs and 

 adults is slight, and in fact most of the young feed mainly 

 on weeds, but the egg punctures (Fig. 182) cause distorted 

 growth and weaken the twjg. Spraying with a fairly strong 

 contact insecticide to destroy the nymphs wherever these 

 are found, and the destruction of all weeds like burdock, 

 thistles, etc., near the fruit trees appear to be the only 

 methods of control, and the former is rarely practicable. 



The Leaf hoppers (Fig. 183) are extremely abun- 

 dant insects and some of them must do much injury 

 to the grass crop as it has been estimated that there 



T 



FIG. 183. Three kinds of Leaf- 

 hoppers enlarged about twice. The 

 left hand figure is of a "spittle in- 

 sect." (Original.) 



FIG. 181. Adult 

 Buffalo Tree-hopper; 

 view from above. 

 Enlarged about 

 twice. (Original.) 



are frequently as many as one to two millions of them per acre. Most 

 of them are very small. 



Some leafhoppers have one generation a year, others more, and 



different species appear to hibernate in 



f different stages. In addition to various 



J&. grasses, grain, alfalfa, clover, sugar beets, 



grape, and rose, the apple, elm, willow 

 and other trees have their juices ex- 

 tracted by the feeding of these insects. 

 A group of tiny leafhoppers known as 



! ' froghoppers or spittle insects (See Fig. 183) 



is also included here. They are common on 

 grasses and other herbaceous plants and also 

 on some trees such as the pine, etc. The 

 nymphs produce a fluid and liberate air in 



this in such a way as to form a sort of froth or "spittle" in which they 

 live. They are very abundant .in the northern states practically across 

 the entire continent, and one species, the Grass-feeding Froghopper 

 (Philcenus lineatus L.) is often so common as to wet the shoes of a person who 

 walks through the grass in June. The nymphs suck the sap from the grass stems, 

 withering and turning white the upper parts of the stems and the blossoms, much 

 as does the grass thrips. Burning over old grass fields where these insects are 

 most abundant, in early spring will destroy many of these insects in their winter 

 quarters close to the ground. 



The Apple Leafhoppers (Empoasca mali Le B. and others), tiny insects 

 about a twelfth of an inch long, attack over fifty different kinds of 

 plants being generally most abundant on the apple, Norway maple, 

 and some kinds of oaks among the list of trees, and on alfalfa, clover, 

 potato and beets. They appear to occur in almost every part of the 

 United States and in some sections of Canada. The adults are 

 generally pale green with white markings on the pronotum. Other 

 similar insects are often present along with these species, but treatment 

 for all would be identical, 



