Many home gardeners enjoy growing pear trees because they produce a sweet, nutritious fruit and are easy to grow. Compared to other types of fruit trees, pear trees need less attention and continue producing fruit year after year. Although pear trees are reasonably healthy, they do encounter several types of insects that cause damage. In addition to regular pruning, pear trees need regular leaf inspections for insect infestations.
Pear psyllas are sucking insects that attack all types of pear trees. They jump on trees and feed on the sap from leaves, producing sticky drops of honeydew that coat both the tree and its fruit. This formation of honeydew damages a tree by interfering with the photosynthesis process. These insects spend their winters close to previously infected pear trees and return in early spring. Once they attack a tree, they start to feed on leaves and eggs which results in future generations on the tree for the duration of a growing season.
A heavy infestation of toxic pear psylla saliva can cause a reduction in fruit crops and early leaf defoliation. Oil sprays combined with insecticides can be effective in treating this problem.
Pear slugs are slimy insects that feed on the surface areas of pear tree leaves. They range in color from dark green to orange and have swollen heads. Although they resemble common garden slugs, pear slugs are actually the immature stage of a non-stinging wasp known as a sawfly. These pests can be controlled by insecticides such as soaps or by washing off larvae with a strong jet of water.
Pear midges are small white maggots that feed on young pears. Signs of pear midges are young fruit that fail to develop properly and instead become black before they fall to the ground. Infected fruit are called bottlers and contain as many as 50 maggots when opened. These maggots grow to about 1/7 inch when mature, according to Chest of Books.com. Destroy all infected fruit and cultivate soil around an infected tree to kill off wintering pear midges by exposing them to cold weather.
Codling moths attack ripening pears, causing two types of fruit damage: deep entries and stings. Deep entries are the result of larvae that's eaten through the skin. Sting entries occur in the place where larvae have died before they've gained entry or where they have started to tunnel into a pear. This insect is more prone to attack in high humidity or where there's considerable rainfall and heavy winds.
Controlling codling moth involves careful monitoring, in addition to timing insecticide applications to concur when larvae are hatched. Insecticides that are applied too soon can result in larvae tunneling into fruit where they aren't affected by insecticides.