Codling moth larvae (small caterpillar stage) hatch in June and
early July. They seek newly developing fruit, which they tunnel
into, usually feeding in the center of the fruit and on the
developing seeds. Look for piles of “sawdust” in July on the
flower end of fruit. They feed on apples and pears, and even the
related landscape plants quince, hawthorn, and crabapple.
Affected fruits, if just with a bite on the surface, usually
merely have a surface blemish. Fruits in which larvae have
tunneled inside drop prematurely.
If using pesticides to control codling moth, follow label
directions, especially in regard to proper timing of spring
sprays. Biorational pesticides—those with a biological
base—although better for the environment may be less effective.
These include bacteria, insect growth regulators, viruses, and
botanically-based products. More on controls and timing can be
found in a Penn State University leaflet
Plum curculio weevils lay eggs in spring on apple, pear, peach,
plum, and cherry fruits once they are pea size. The eggs hatch
into larvae, which feed on fruit, causing them to drop. Larvae
feed on seeds of pome fruits (such as apples) but not of stone
fruits (such as cherries). If fruits remain, they show D-shaped
scars or deformities. If spraying for other pests in the spring,
this one usually will be controlled as well. Especially watch for
this pest in spring on trees near hedgerows or woods where this
pest may be present.
The European apply sawfly lays eggs on the base of apple flowers
during bloom, which hatch into larvae. These feed on fruit,
causing a winding scar, then tunnels and holes. As a result, many
immature fruit fall off. Controls for the plum curculio also
control these sawflies.
There are several species of trunk borers that kill fruit trees.
Adult beetles lay eggs on lower parts of tree trunks in summer.
The larvae that hatch tunnel throughout the trunk, causing
structural damage and a site for wood rot diseases to enter.
Especially susceptible are young, unsprayed trees, and those with
close-fitting tree guards. Such guards, put on to deter mammal
feeding, provide an ideal site for these borers to lay their
eggs. Removing these guards in spring helps to lessen this pest.
This insect, too, is usually controlled by sprays for others
orchard pests so is most often found on wild or unsprayed trees.
One of the best controls for this pest is to keep trees healthy.
If planting new ones, or near landscapes, keep them at least 300
yards away from other host plants for this pest. These include
crabapples, hawthorns, and shadbush. Keeping brush and grass
mowed and away from trunks allows natural predators such as
woodpeckers and parasitic wasps to find these pests.
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