HORTICULTURE HORTICULTURE
Common Tree Fruit Insects
by Mark Longstroth
Disrict Extension Horticultural and Marketing Agent
Apple, Blueberry and Cherry Maggots
The picture ing fruit flies emerge as adult flies
from the soil, where they overwintered as pupae. Cherry maggot
emerge about the first week of June; apple maggot and blueberry maggot during the first week of July. Times may vary
somewhat, depending on location. After emergence, females go through a 7 to 10 day
preoviposition period before mating and laying eggs. During this time they are attracted
to leaves and feed on aphid honeydew and leaf exudates, which provide nutrients for egg
development.
Yellow sticky traps attract many flies from relatively short distances (1 to 10 feet)
during this period. Ammonium compounds such as ammonium stearate, ammonium acetate, even
household ammonia or protein hydrolystate blended in the Tanglefoot of purchased traps,
can enhance the trap's effectiveness because they mimic the smell of aphid honeydew.
For best results, place traps one-third of the way into the tree on the south side, and
remove foliage and twigs from at least 1 foot around them. One to three traps per tree
should provide good control of the newly emerged flies. For blueberry maggot control, one
or two baited yellow traps per bush should be adequate. Maggot emergence continues through
mid-September, so clean traps weekly and replace every two weeks through harvest. Apple
maggot damage is often worse on summer varieties of apples, but it continues through
harvest of later maturing varieties.
After the preovipositon period, the fly's behavior changes and it begins searching for
mating and egg laying sites. Flies are still attracted to yellow panels, but red spheres
or Ladd traps are more effective during this period because they resemble the fruits where
flies would normally mate and lay eggs.
Hang red spheres on the south side of the tree at about eye level and one-third of the way
inside the tree canopy. Remove foliage from about 1 foot around the traps. One trap per
100 apples provides about 95 percent control of apple maggots. To enhance trap
effectiveness, add the ammonia solution, or the synthetic attractants that mimic the odor
of ripe fruit. Also see the fact sheets on apple maggot, blueberry, cherry fruit fly
at this site
Tarnished Plant Bug
This common pest of backyard fruit
trees can cause considerable damage. Damage resembles a deep dimple in the fruit. If
insects are present in large numbers, some method of control is recommended. Adults
overwinter and feed on swelling buds in the spring. When feeding occurs before the pink
stage of apply bloom, the damage blossoms will fall. Feeding after that time causes fruit
deformity.
During the pink flower bud stage of apples, you can trap tarnished plant bugs with a
non-UV-reflecting white sticky trap. To the insect, it resembles an extremely large petal.
Place the trap on the outside of the tree on the south side at about eye level. One trap
per tree should provide sufficient control on dwarf trees, but two to three evenly spaced
traps are needed on large trees. Remove foliage from within 1 foot of the trap so it is
readily visible to insects approaching from any direction. Traps can be removed in
early June because the insect will seldom feed on developing fruit.
See the Tarnished Plant Bug Factsheet for more information.
Codling Moth
Codling Moth can be
severe in home fruit trees and control may be required. Damage is caused by the larvae,
which burrow into the apple and feed in the seed cavity. It can be distinguished from
other internal fruit feeders by the presence of frass-sticky brown feces-which is pushed
out the tunnel behind it.
Mass trapping and disorientation experiments using pheromones to control the codling moth
have been attempted in commercial settings but have been unsuccessful unless dispensers
were placed in every tree. In backyard settings where much more damage can be tolerated,
these trapping/disorientation techniques may yield satisfactory control. This has yet to
be demonstrated, however.
Currently, the best use of the codling moth pheromone is to help determine the timing of
pesticide applications. Apply insecticide sprays 14 days after the first male is
caught-about petal-fall stage-or immediately after the fifth male is caught. This spray
will kill hatched larvae before they penetrate the fruit. Two generations of codling moth
occur each year. Use the same principle for the second generation, which begins in
mid-July, but apply the spray 7 days after the first male is caught.
Put out traps at tight cluster
to pink, approximately April 15. When trap catches are 2 to 3 codling moths per trap - we
call this the biofix, around mid to late May. Time sprays for hatching larvae at 250
degree days base 50 after biofix the first or second week of June. A second spray 10 to 13
days after the first may be needed for sites with high codling moth pressure. Codling moth
entries into apple fruit are seen about mid June.
Pheromone capsules should be changed at the end of June, to detect the new flight in July.
Larvae from the 1st generation will mature, pupate, and hatch resulting in moth catches
about the end of June to early July, about 1200 degree days from the biofix in May. Sprays
for this new crop of larvae are applied about 1400 degree days base 50 from the May
biofix, before emergence.
Redbanded Leafroller
The Redbanded Leafroller
is generally an indirect pest of fruits because it feeds on foliage and seldom on the
fruit itself. Infrequently it is a severe pest, but its pheromone provides a good
demonstration of how effective and powerful pheromones are. Males are usually attracted
within 5 minutes of exposing a cap to air currents on a warm midafternoon in late April.
Don't let the high populations of this pest alarm you-this insect is a general feeder and
has larger populations on hosts other than fruits.
Set these traps out in early April. Change the cap and trap every four weeks. Mass
trapping and disorientation is ineffective in commercial situations, but the trap will
indicate when the pest is flying.
Oriental Fruit Moth
This is a significant pest of peaches in North
Central region and also affects apples in some areas. First generation adults appear in
early May; their offspring feed on tender fruit twigs and terminals. Second generation
adults appear in mid-July; their larvae feed internally on the fruit, causing mushy, wormy
fruits. Third generation adults appear in late August, and their larvae also feed in the
fruit.
The pheromone for this insect is quite effective in capturing males. Use caps and traps as
described for codling moth, but replace traps before each new generation of adults appear.
Neither mass trapping nor mating disruption is likely to provide control, but traps will
indicate when to apply chemicals for best adult control.
Over winters as full grown
larvae. Put traps into orchard at tight cluster (apple), about April 15. Traps are used to
detect 1st, 2nd and 3rd generation adult flight.
First generation, time insecticide sprays for hatching larvae at 200 degree days base 42
beyond the point when accumulated trap catches of adult male moths are more than 1
oriental fruit moth per trap, approximately the 1st of June, followed by a second spray
200 degree days base 42 after that. On peaches, the first sign of larval activity is the
flagging of peach terminals due to the burrowing larvae.
Adults of the 2nd generation appear about the end of June. Damage appears about 10 to 14
days after emergence. Use the adult emergence date as the biofix and spray 200 degree days
base 42 after the first.
Oriental fruit moth has a third generation that can be a problem on late apples. Monitor
and spray when trap counts become greater than 8 oriental fruit moths per trap per week.
The need for sprays for other pests such as apple maggot late into the season may also
enter into the decision process.
Use of pheromone traps and degree day models is a more precise way to tailor insecticide
sprays to the year and orchard. Experience is the best guide for the use of these tools.
Also see the Oriental fruit moth factsheet at this site.
Peachtree Borer
Almost every peach tree and many cherry and other stone fruit trees are infected with these clearwing moths that resemble wasps. Larvae cause damage by feeding in the inner bark or cambium layer of the tree trunk. Their presence is indicated by their frass, which is pushed out through cracks in the bark, and by the gum the tree producers. Recent research in the South shows progress in using pheromones for mating disruption as a non-chemical control. Traps are best used, however, to indicate when trunk sprays should be applied for adult control to prevent egg laying. Also see the Tree borer factsheets at this site on trunk Borers such as American plum borer, lesser peach tree borer and peach tree borer.
Cornell University has excellent Fruit Insect Fact Sheets available on the Web.
