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Jumping Plant-lice or Flea-lice — Part 1

(Family Psyllidae.)

These insects have two-jointed tarsi, antennae eight-or-nine-jointed, and the hind legs with somewhat swollen thighs. Their 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."

Life History of the Pear-Tree Psylla

(Psylla pyricola.)

This insect is the commonest and the most destructive flea louse in the United States. It is common throughout the northeastern United States and from Maryland on the south to Michigan on the west. It was originally a European species and is supposed to have been imported into this country about 1832, making its first appearance in Connecticut. The egg is orange yellow in color and very minute. It is attached to the leaf by a short arm and has a long hair-like stalk projecting from its end. The newly hatched larva is somewhat larger than the egg and yellow in color with crimson eyes. It passes through several molts and when nearing the nymphal condition, which corresponds to the pupa stage in insects which have complete metamorphoses, it is readily distinguished by the large wing pads. Its color is then dark reddish brown. In all the early stages the insect is broad-oval and very much flattened, resembling more nearly some scale insect rather than a perfect flea-louse. It is also sluggish in these early stages. When the nymph casts its last skin the adult insect emerges. It resembles much more closely a minute cicada or harvest-fly than any other homopterous insect. It hibernates in the adult stage in crevices in the bark of pear-trees and emerges with the first warm spring days, beginning with the laying of the eggs on the leaves before they have fully expanded or even placing them in cracks in the bark on the twigs. The larvae hatch in ten to seventeen days and station themselves on the surface of the leaves or on the leaf petioles. There are four or five generations each summer in Maryland but fewer farther north.