THE JUMPING PLANT-LICE OR FLEA-LICE- 



(Family Psyllidce.) 



These insects have two-jointed tarsi, antennae eight-or-nine- 

 jointed, and the hind legs with somewhat swollen thighs. Their 



<"7_ ! a 



Fi g- 1 53-— Galls of Pachypsylla venusta O. S. (Alter Riley ) 



jumping habit distinguishes them from the plant-lice as indicated 

 in the popular name. Certain species exude quantities of the 

 sweet liquid known as honey-dew, which is also abundantly 

 secreted by the plant-lice and by some of the tree-hoppers and 

 leaf-hoppers. Many forms live in galls and there are several 

 species which produce galls of different kinds upon the trees of 

 the genus Celtis, commonly known as " hackberry trees." 



259 



