Pear psylla

Cacopsylla pyricola

Description. Pear psylla is one of the most serious insect pest of pears because of its ability to develop resistance to insecticides and to vector the pathogen that causes pear decline.
Overwintering pear psylla adults are somewhat darker and larger (0.125 inch or 3 mm) than summer adults (0.08 inch or 2 mm). Adults hold their transparent wings rooflike over their dark to reddish brown bodies when at rest; they resemble tiny cicadas. A dark spot on the top middle edge of both wings helps to distinguish pear psylla from other psylla. Tiny, elongated yellowish eggs, which are barely visible without a hand lens, are laid on or near fruit spurs starting in late January or early February. As buds open, females lay eggs along midribs and petioles of developing leaves or on stems and leaves of blossoms. Pear psylla nymphs pass through five instars, four of which are almost completely encased in honeydew. When first hatched, the tiny nymphs are yellow with red eyes and black antennae. The third stage is yellowish green and the fourth greenish brown. The fifth instar is called the hardshell stage and it is dark with prominent wing pads.
Damage. Pear psylla is a greater problem on European varieties than on Asian varieties. Pear psylla damages pears in several ways. Loss of crop and tree vigor, and sometimes loss of trees, can occur from pear decline disease, caused by a phytoplasma organism that psylla injects into pear trees. Pear decline has varying effects on the trees depending on variety, rootstock, quality of the growing site, and pear psylla numbers.
Honeydew, produced by psylla nymphs as they feed, drops onto fruit. A black sooty mold grows on the honeydew and the fruit skin russets, which downgrades fruit for fresh-market use. Psylla feeding and injection of a toxin into the tree causes portions of the leaf blade to blacken, and leaves to yellow and sometimes fall. Growth and productivity of the tree can be severely reduced for one or more seasons.

Plant Protection Products