Psylla pyricola Foerster
The pear psylla, a small cicada-like insect about 1/10 inch long, is a serious pest in the pear-producing areas of the United States. It is responsible for a black discoloration of the fruits and is also the vector for the virus that causes pear decline on trees grown on oriental rootstocks.
The psylla, hibernating as adults in crevices in the bark and under bark scales on the trees, or under debris on the ground, become active when the temperature exceeds 40 °F. Eggs laid in crevices around the buds hatch in 10 to 30 days. Larval and adult forms feed only on the foliage of the trees and secrete honeydew that runs down over the leaves and the fruits. A black fungus grows in the honeydew, causing spotting of the leaves and blackening and scarring of the fruits. Some of the superficial mold growth can be removed when the fruits are washed, but the remaining fungus and the scar tissues result in downgrading of the fruits (see photo).
An insecticide spray program is necessary to control pear psylla. Recommendations of the State agricultural extension service or experiment station should be followed.
Pear psylla injury