52 INSECTS 



scales produce honey-dew in great quantity, and the 

 resulting soot fungus does almost as much injury as 

 the insect. In the olive and citrus groves of the Pacific 

 Coast, trees infested by the black scale are often recog- 

 nizable as far as they can be clearly seen, and discolora- 

 tion of fruit is a distinct element of the injury caused. 



Quite a number of others among the allies of scales 

 and plant lice produce honey-dew and its consequences, 

 and there is a long series of species, including the leaf- 

 hoppers, tree-hoppers and others of the Homopterous 

 section, that cause more or less injury to their food 

 plants by the direct robbery of the vital juice or sap; 

 but there are none differing so greatly from the methods 

 of plant lice and scale insects as to require special 

 attention here. 



A somewhat different type of injury is caused by 

 some tree-hoppers and Cicadas or harvest flies. These 

 do little or no harm by direct feeding; but utilize the 

 twigs and branches of the plants on which they live 

 as places of deposit for their eggs in such a way as to 

 kill or severely cripple them. Some of the tree-hoppers 

 cut little slits in the twigs to receive their eggs, and 

 these slits never heal. The tendency is rather to an 

 enlargement of the scar which permanently weakens the 

 shoot and sooner or later causes a break. The chief 

 sinner in this direction is the periodical Cicada, better 

 known as the "17-year locust," and wherever and 

 whenever that makes its appearance in numbers, the 

 tips of the forest trees in early fall show brown ends 

 as if a fire had passed over them. In such forests it 

 means only a moderate pruning and no real injury to 

 the trees; but in orchards, especially of young trees, 

 injury is often severe, weakening the shoots and branches 

 so that they break under a load of fruit. And these 

 punctures also refuse to heal, and remain permanent 



