pear tree with fruit
Updated: July 8, 2021

1.  Aphids - rosy apple, green apple, and woolly apple

  • There are three types of aphids that infest apples: rosy apple, woolly apple, and green apple aphids.
  • Rosy apple aphids are very destructive because their feeding causes the fruit to be small and badly deformed.
  • Green apple aphids feed primarily on young, succulent tip leaves and may or may not cause significant damage.
  • The superior-oil spray applied at the green tip stage will help reduce the aphid populations, but rosy apple aphids generally require additional treatments with an insecticide at the tight cluster and pink stages just before bloom.
numerous small green aphids on underside of leaf
Apple aphid, Aphis pomi
Photo: Kansas Department of Agriculture, 
Bugwood.org

2.  Codling Moth, (Cydia pomonella)

  • A very common, destructive insect pest and is the most common “worm” found in apples.
  • Females of the first generation lay eggs during the petal fall period, and the larvae burrow into young fruits causing them to drop early.
  • Adults become active when mean temperatures exceed 60 degrees F.
  • Cool spring weather will delay emergence and extend the mating and egg-laying activity.
  • With later generations, eggs are often laid directly in fruits, and the larvae tunnel through the flesh causing wounds that are often followed by fungal rots.
  • A typical sign of codling moth activity is a small hole on the outside of fruits that may show traces of sawdust-like frass around the edges.
  • When the fruit is cut, a small, pinkish-white larva can be found in a tunnel leading from the hole on the outside to the core.
  • Control efforts must be aimed at early generations to keep later populations from becoming so large that major fruit loss occurs.

Additional Resource:
Colorado State University - Codling Moth: Control in Home Plantings

codling moth larvae (worm) inside an apple
Codling moth larvae, Cydia pomonella
Photo: Ward Upham, Kansas State 
University, Bugwood.org
damage to outside of apple from codling moth
Codling moth damage to apples
Photo: Whitney Cranshaw, Bugwood.org

Nonchemical management of coddling moth

• Hang plastic traps (empty 2-liter soda bottles) filled halfway with molasses, vinegar, and water, from tree limbs at petal fall.
• Cover individual fruit after pollination with small paper bags.
• Remove infested fruit from tree.
• Band tree trunks with folded corrugated cardboard to trap larvae leaving trees to pupate in bark or    in soil.
• Scrape loose bark off tree during dormant season to remove overwintering larvae.
• Lightly cultivate soil prior to bud swell to disrupt/kill overwintering larvae.
• Pheromone traps can be used to trap adult male moths. Hang two per tree at bloom and replace the pheromone every 8-9 weeks. These traps are most effective for monitoring codling moth adult males and can be effective if monitored and managed regularly. The risk exists of attracting more males to the area than can be trapped, leading to an increase in egg deposition by females.

3. Mites

closeup of two spotted spider mite
Two-spotted spider mite
Photo: 
Frank Peairs, Colorado State University, Bugwood.org
  • Spider mites can be a problem on both apples and pears.
  • The most common species is the European red mite whose eggs overwinter on the bark and bud scales.
  • A second troublesome species is the two-spotted mite, which spends the early season on the ground and then moves into the trees during the summer.
  • The eggs of the European red mite are tiny, shiny, red spheres laid around buds and on leaves and fruit.
  • The adults are tiny, reddish, oval- to pear-shaped spiders that move readily when disturbed.
  • Two-spotted mites are also pear-shaped but are yellowish, and two distinct dark spots can be seen on the back when viewed with a hand lens.
  • With both species, the feeding of high populations causes the foliage to appear bronzed on apples and brown to black on pears.

4. Apple maggot, (Rhagoletis pomonella) 

puckering and dimples on apples
External appearance of apples damaged by the apple maggot
H.J. Larsen, Bugwood.org
  • Not a serious and widespread pest across Maryland although it can cause significant fruit injury in home gardens.
  • The adults are small black flies with clear wings that have black markings.
  • Female flies insert their eggs under the fruit skin. Egg laying causes dimpling of the fruit surface.
  • Maggot feeding creates brown winding tunnels through the fruit.
  • The maggots complete their lifecycle in the soil after infested fruits drop to the ground.
  • Adult flies can be monitored and caught with traps of red spheres (resembling apples) coated with petroleum jelly or other sticky substance. The sticky spheres are tied to string and hung from tree limbs in mid-June.

5. Pear psylla

  • This is a sucking insect that can be detrimental to pears.
  • If uncontrolled, high populations of this pest can cause early defoliation, complete fruit loss, and tree decline. Adult psylla look like tiny cicadas.
  • The immature nymphs of pear psylla secrete large amounts of sticky honeydew on fruit and foliage surfaces.
  • The honeydew is colonized by various sooty mold fungi that turn the fruit and foliar surfaces black.
small brown spots on pear leaves
Pear psylla damaged leaf
Photo: Whitney Cranshaw, Colorado State University, Bugwood.org

6. Plum curculio, (Conotrachelus nenuphar)

plum curculio feeding on fruit
Adult plum curculio inserting snout into fruit
Photo: U. of MN Extension
crescent shaped scars on fruit
Crescent-shaped scars
Photo: NHFruitGrowers.org
  • Plum curculio is a gray snout beetle that is about 1/4-inch long.
  • It is a major problem on  fruits because the eggs are laid in the fruit. Adults become active when mean temperatures exceed 60°F.
  • Cool spring weather will delay emergence and extend mating and egg laying activity. When the larvae hatch, they eat through the fruit flesh to the seed and cause the fruit to drop.
  • The most serious damage on apples occurs in the first month after petal fall when egg laying on very young fruits causes severe deformities and early fruit drop in June.
  • Larvae that successfully hatch and grow will tunnel through the fruit flesh to the seed.
  • Attempts by later generations to lay eggs in the hard apple fruit are seldom successful, but the oviposition scar develops into a characteristic slightly raised, shield-shaped russet spot approximately 1/4- to 3/4-inch in diameter.
  • These later injuries are unsightly but do not seriously reduce the quality of the fruit.

Nonchemical management of plum curculio

• Hang plastic traps (empty 2-liter soda bottles) filled halfway with molasses, vinegar, and water,          from tree limbs at petal fall.
• Cover individual fruits after pollination with small paper bags.
• Remove infested fruit from the tree.
• Lightly cultivate soil prior to budswell to disrupt/kill overwintering adults.
• Keep trees pruned and open (curculios prefer deep shade).
• Lay a white sheet under trees, tap limbs with a padded stick, and capture adults when they drop to the ground.

7. Scale insects

  • Are tiny, aphid-like, sucking insects that spend part of their life cycle under a waxy shell, or scale, of their own making. In large numbers, their feeding causes shoots and small branches to dieback. In addition, they excrete honeydew in large amounts, making leaves and fruit sticky and heavily blackened as sooty molds develop.
  • Where scale insects are well established, heavily infested limbs need to be cut out and destroyed and a thorough superior-oil plus insecticide spray applied early in the spring at the green tip stage. Later generations are usually controlled by sprays applied for codling moth control.

8. Brown marmorated stink bug

external damage on the surface of apple from brown marmorated stink bug feeding
External BMSB damage

 

brown marmorated stink bug
Brown marmorated stink bug
Photo: G. Hamilton, Rutgers