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Ministry of Agriculture, Food and Rural Affairs

Oriental Fruit Moth (OFM)

Oriental fruit moth larva Anal comb (black structure) found on Oriental fruit moth larvae Oriental fruit moth adult Flagging Larval excrement on shoot surface Visible external damage from larva Late season fruit damage Typical oriental fruit moth tunneling damage Black structure found on oriental fruit moth larvae

Click to enlarge.

Beginner

Scientific Name
Grapholita molesta

Identification
Eggs:

  • Laid individually,
  • Appear as flat scales,
  • Semi-transparent white,
  • 0.5-0.7 mm in diameter.
  • Eggs are rarely seen in orchards

Larvae:

  • Newly hatched larvae are 1.5 mm long with a black head and white body,
  • Mature larvae reach 9-13 mm in length with a brown head capsule and a cream to pinkish body,
  • A small, dark, comb-like structure called an “anal comb” can be seen using a good quality hand lens or, if the larvae are very small, using a microscope,

Adults:

  • Small moth (about 6-7 mm),
  • Greyish-brown with silvery scales on their wings,
  • Underside of forewings is light coloured.

Damage:

  • Adults and larvae attack both apple shoots and developing fruitlets.
  • Terminals appear somewhat desiccated, with limited drooping, and eventually turn brown as the tissues die.
  • Examination of affected shoots often reveals a small entry hole, with frass present.
  • Larvae tunnel into fruit from the calyx or stem ends.
  • Frass produced by the developing larvae is often evident on the fruit surface. 
  • Infested fruit often colour prematurely. 
  • Larvae generally tunnel inside the flesh of the fruit.

Often Confused With

  • Codling moth- Codling moth larvae do not possess an anal comb. Adult oriental fruit moths are much smaller than codling moth adults, and lack the characteristic bronzed area at the wing tip
  • Lesser appleworm- Appleworm larvae also tunnel into terminals causing flagging. Apple worm larvae possess an anal comb and are difficult to distinguish from oriental fruit moth. The moths are similar in overall appearance to oriental fruit moth, but have a metallic copper hue and thin bands of pale blue on their wings.  

Period of Activity
There are three or four generations of oriental fruit moth each year. Adults begin emerging as early as tight cluster. Terminal flagging and damaged fruit may begin to appear in orchards in mid June, and may continue through harvest.  

Scouting Notes
OFM is a regional pest and damage only occurs in Norfolk/Brant, Middlesex/Lambton, Essex/Kent. Use pheromone traps to monitor oriental fruit moth adult activity and determine insecticide application timing. Place traps in the orchard prior to the anticipated first flight in the spring (late April). Replace traps at the end of the flight period for each generation). Leave traps in the orchard until harvest is completed. A minimum of one set of five traps per four hectares is recommended to provide an accurate representation of activity in the field.

Use sentinel pheromone traps in blocks where mating disruption for oriental fruit moth has been applied. For more information on mating disruption refer to OMAFRA Factsheet Mating Disruption for Management of Oriental Fruit Moth in Stone and Pome Fruit (Order No.04-029).

Monitor traps twice per week on the same days each time (e.g. Mondays and Thursdays) during periods of activity.  Remove all moths and record the data. The specific timing of pest control products varies depending on the target life stage, the insecticide’s mode of action and residual activity.

Thresholds
As a general rule, if pheromone traps are catching >10 moths each week, control measures are likely needed. Insecticides for first generation are often applied 6-10 days after upswing in pheromone trap counts, which often coincides with petal fall. A repeat application may be needed if emergence is extended. A model has been developed to time the application of insecticides for OFM. Begin accumulating degree days (base 7.2˚ C) at the first sustained moth catch (biofix). For products targeting newly hatched larvae timing is approximately 194-208 DDC for the first brood. For second generation apply insecticides at 805-833 DDC, and for third generation at 1361-1389 DDC, followed by a second application at 1611-1667 DDC.

Advanced

Scientific Name
Grapholita molesta

Identification
Eggs are laid individually and appear as small, flat semi-transparent white scales 0.5-0.7 mm in diameter. Newly hatched larvae are 1.5 mm long with a black head and white body. Mature larvae reach 9-13 mm in length with a brown head capsule and a cream to pinkish body. Oriental fruit moth larvae are very similar in appearance to those of codling moth and a closely related species, the lesser apple worm – that occasionally infest apples in Ontario. Codling moth and oriental fruit moth larvae are distinguished by close examination of the last abdominal segment. Oriental fruit moth larvae possess a small, dark, comb-like structure called an “anal comb” which can be seen using a good quality hand lens or, if the larvae are very small, using a microscope.

Adult oriental fruit moth are small (about 6-7 mm), greyish-brown moths with silvery scales on their wings. The underside of forewings is light coloured. Adults are much smaller than codling moth adults, and lack the characteristic bronzed area at the wing tip. Lesser apple worm moths are occasionally caught in oriental fruit moth pheromone traps usually just before first generation oriental fruit moth adults are caught.

It is critical to correctly identify the pest, as the biology and management strategies of codling moth and oriental fruit moth are different. If in doubt, collect and store infested fruit for examination by a crop consultant or entomologist. 

First generation oriental fruit moth larvae attack both apple shoots and developing fruitlets, causing direct and indirect damage. Feeding activity of larvae in apple shoots does not result in the obvious flagging as observed in peach, and is easily overlooked without close examination of terminals. Oriental fruit moth “strikes” to apple shoots cause terminals to appear somewhat desiccated, with limited drooping, and eventually turn brown as the tissues die. Examination of affected shoots often reveals a small entry hole, with frass (insect excrement) present.

Often Confused With

  • Codling moth- Codling moth larvae do not possess an anal comb. Adult oriental fruit moths are much smaller than codling moth adults, and lack the characteristic bronzed area at the wing tip
  • Lesser appleworm- Appleworm larvae also tunnel into terminals causing flagging. Apple worm larvae possess an anal comb and are difficult to distinguish from oriental fruit moth. The moths are similar in overall appearance to oriental fruit moth, but have a metallic copper hue and thin bands of pale blue on their wings. 

Biology
There are three generations of oriental fruit moth in Ontario. A partial fourth generation may develop in some years, with adult flight and egg-laying activity extended into October. Eggs from this generation hatch and larvae move into fruit prior to harvest. Late season damage is difficult to detect because larvae are small. Infested apples may get through packing lines undetected.

The insect overwinters as a late stage (fourth or fifth instar) larva within a cocoon under bark scales, crevices and other protected areas on the tree or on the ground. The larva pupates in the spring and emerges as an adult in late April or early May. Numbers of overwintering adults captured using pheromone traps are greater in apples than in nearby peach orchards, presumably due to the high levels of oviposition on apple and subsequent survival of later generation larvae the previous fall. Mated females lay up to 200 eggs. Oriental fruit moths have a base development temperature of 7.2º C and require an accumulation of approximately 550 DDC (base 7.2ºC) to go from an egg to an adult (generation time). Development occurs more slowly in apples than in peaches. Adults are considered to be strong fliers.

Period of Activity
There are three or four generations of oriental fruit moth each year. Watch for this pest from the end of tight cluster through harvest. Terminal flagging and damaged fruit may begin to appear in orchards in mid June, and may continue through harvest.  

Scouting Notes
OFM is a regional pest and damage only occurs in Norfolk/Brant, Middlesex/Lambton, and Essex/Kent. Fruit is attacked by all generations of oriental fruit moth. Females appear highly attracted to fruit previously damaged by other internal feeders. When larvae hatch, they enter the fruit through either the calyx or stem ends. In apple, larvae often exit via the same hole they entered. Research indicates very few oriental fruit moth larvae enter the fruit by the side of the fruit (in contrast with codling moth). Most larvae enter fruit within hours of hatching, emphasizing the importance of timing and coverage of insecticides. Frass produced by the developing larvae is often evident on the fruit surface and infested fruit develop colour prematurely. Most feeding is hidden within the fruit. In contrast, lesser appleworm feeding is often just under the surface of the skin.

Oriental fruit moth larvae generally tunnel inside the flesh of the fruit avoiding the seeds, while codling moth larvae move directly into the seed cavity where they begin feeding on seeds.

Use pheromone traps to monitor oriental fruit moth adult activity and determine insecticide application timing. Place traps in the orchard prior to the anticipated first flight in the spring. Replace traps at the end of the flight period for each generation. Leave traps in the orchard until harvest is completed. A minimum of one set of five traps per four hectares is recommended to provide an accurate representation of activity in the field. Trap height for oriental fruit moth is not critical. Ensure trap openings are not blocked by foliage. Place one trap at the edge of the orchard and the rest of the traps at 40 m intervals following a row into the orchard. Use sentinel pheromone traps in blocks where mating disruption for oriental fruit moth has been applied. If mating disruption is working properly, very low or no oriental fruit moth should be captured in these traps. This indicates that mating disruption is performing effectively. 

Monitor traps twice per week on the same days each time (e.g. Mondays and Thursdays) during periods of activity. Remove all moths and record the data. The specific timing of pest control products varies depending on the target life stage, the insecticide’s mode of action and residual activity. Pheromone trap catch data provides critical information for management of oriental fruit moth using either insecticides or mating disruption technology.   

Fluctuating spring temperatures affect trap catch data. Just as there is a base temperature below which no development occurs in larvae, there is also a minimum temperature required for activities including adult flight, searching for a mate and egg laying. During cool night time periods early in the growing season, adult oriental fruit moth may not be active in the orchard. When warmer temperatures resume, so does flight activity. This may give the impression that flight of the second generation has begun, when in fact the activity represents a split or bimodal peak of the overwintering generation.  Bimodal peaks often carry over to the next generation. Pheromone traps provide information on insect activity, and degree day models predict when subsequent generation flight occurs.

Thresholds
As a general rule, if pheromone traps are catching more than 10 moths each week, control measures are likely needed. Insecticides for first generation are often applied 6-10 days after upswing in pheromone trap counts, which often coincides with petal fall. For subsequent generations insecticides are applied three to six days after upswing in trap counts. A repeat application may be needed if emergence is extended. A model has been developed to time the application of insecticides for OFM. Begin accumulating degree days (base 7.2˚ C) at the first sustained moth catch (biofix). For products targeting newly hatched larvae timing is approximately 194-208 DDC for the first brood. For seconnd generation apply insecticides at 805-833 DDC, and for third generation at 1361-1389 DDC, followed by a second application at 1611-1667 DDC.

Management Notes

  • Larvae enter the fruit within 24 hours of hatching, leaving a very narrow window to manage the pest using insecticides.
  • The specific timing of pest control products varies depending on the target life stage, the insecticide’s mode of action and residual activity. For more information on the timing of specific insecticides to manage oriental fruit moth refer to OMAFRA Publication 360, Guide to Fruit Production - Chapter 3 Apples (PDF) or Apple Calendar only (PDF) :
  • Degree-day models provide important information for predicting the timing of insecticide applications, but are not a replacement for continued monitoring of pest activity with pheromone traps and field scouting for damage.
  • The model for oriental fruit moth differs between apples and peach.  For information on managing oriental fruit moth in peach refer to OMAFRA Publication 360, Guide to Fruit Production (click here).
  • Monitor flight for each generation; check residual activity for each product and re-apply product if necessary. If emergence and/or activity for that generation are prolonged (bimodal or split peaks), apply a second application of the same product.
  • Manage each generation as separate units when using insecticides. Use products from a single chemical group to manage a given generation of a pest.
  • Mating disruption of oriental fruit moth is a highly effective alternative to insecticides. For more information, consult OMAFRA Factsheet 03-079, Mating Disruption for Management of Insect Pests, and OMAFRA Factsheet 04-029, Mating Disruption for Management of Oriental Fruit Moth in Stone and Pome Fruit.