JUMPING PLANT-LICE. 137 
The insect is said to lay its eggs in single rows in the wood 
of canes, in some cases preferring, greatly to the sorrow of the 
fruit-grower, the canes of the grape-vines, in which case the 
insect becomes a great pest. Besides attacking the leaves it 
punctures the stems of the bunches of grapes with its beak, caus- 
ing the stems to wither and the bunches to drop. Sometimes 
it pumps out the sap so vigorously from the succulent branches 
that the drops fall in quick succession from its body. It is also 
found in large numbers in willow trees, and the united work of 
many insects causes a light shower of sap to fall to the ground. 
In this way they transform the common willow trees into ver- 
itable “weeping” willows. 
Fic. 128—Oncometopia (Proconia) undata Fab. a, from above; b, from side; c, 
under wing. Original. 
FAMILY PSYLLIDAE. 
(Jumping Plant-lice). 
This is a family of rather small insects, few of which occur 
in Minnesota, none measuring more than one-sixth of an inch 
in length. When they are examined with a magnifying lens they 
are seen to resemble minute cicadas. They differ from the true 
plant-lice,or Aphides, by a firmer texture of the body, stouter limbs, 
