Agriculture: Peach Pest Management Guidelines

Oriental Fruit Moth

  • Grapholita molesta
  • Description of the Pest

    The adult oriental fruit moth is small, grayish, and about 0.4 inch (10 mm) long. This moth normally flies in the evening, just after sunset, but occasionally flies between daybreak and sunrise. Eggs are usually laid on the tops of leaves and are disk-shaped, white to creamy when first laid, and about 0.03 inch (0.8 mm) in diameter. Just before hatching, the black head of the developing larva becomes visible. Larvae are white with a black head when first hatched. As they mature, they gradually turn pink with a brown head. Mature larvae are about 0.5 inch (12 mm) long. Use a hand lens to detect the presence of an anal comb under the last abdominal plate (sclerite), which helps distinguish oriental fruit moth larvae from other white or pink worms, such as codling moth, that may be found in stone fruits.

    Oriental fruit moth usually produces five generations per year in California, although a sixth generation has been observed in years with warm weather in early spring and late fall. Oriental fruit moths overwinter as mature, inactive (diapausing) larvae inside tightly woven cocoons in protected places on orchard trees or in the debris near the bases of trees. In early spring, they pupate inside their cocoons and adults begin emerging in February or early March.


    First- and second-generation larvae mine young, tender shoots, causing the shoots to wilt and die (symptoms known as shoot strikes or flagging). Subsequent generations may feed on shoot terminals and green fruit, but as fruit matures, it becomes this pest’s preferred site of feeding. Early-stage larvae generally enter the fruit at the stem end and may not leave noticeable entry marks, although entry can be made anywhere on the fruit, particularly where two fruits touch. Larvae immediately bore to the center of the fruit and feed around the pit. After reaching maturity, they exit from the fruit and pupate.


    Mating disruption is the preferred management strategy for oriental fruit moth. Alternatively, insecticide sprays timed according to degree-day accumulations can be used. Selective insecticides can be integrated into an integrated pest management program. Careful monitoring is critical for success when using these management tools.

    Biological Control

    Macrocentrus ancylivorus is a common parasitoid of oriental fruit moth and peach twig borer larvae. In orchards where broad-spectrum insecticides are not used, parasitism can reach 80 to 90% by August and September, which helps provide long-term control of these pests. Studies indicate that growing a small plot (0.3 to 0.5 acre) of sunflowers within 25 to 50 feet of an orchard can provide Macrocentrus with an overwintering host (the sunflower moth, Homoeosoma electellum), which allows Macrocentrus numbers to increase more rapidly in the orchard the following season.

    Organically Acceptable Methods

    Provide habitat for natural enemies. Use mating disruption and a certified organic formulation of spinosad in certified organic orchards.

    Monitoring and Treatment Decisions

    Establishing Biofix and Accumulating Degree-Days

    Put pheromone traps in the orchard by February 7 to detect the first moth emergence (see Pheromone Traps). Once the first moth is found in a trap (biofix), accumulate degree-days to estimate the onset of the second flight. Use a lower threshold of 45°F and an upper threshold of 90°F. The second flight should begin about 920 to 1,010 degree-days (DD) from the beginning of the initial flight; in some areas, however, the second flight may be seen in as early as 800 DD. Calculate degree-days for oriental fruit moth in peaches for your location using the oriental fruit moth pest model or degree-days table. To learn more about using degree-days to time insecticide applications, watch the degree-days video. Continue using pheromone traps throughout the growing season until the crop is harvested to detect late-season peaks or migrations of moths from adjacent orchards.

    Monitor shoot strikes (see Shoot Strike Monitoring) in late April, mid-June, and mid-July and sample fruit every week with an emphasis on the final 4 weeks before harvest (see Preharvest Fruit Samples). Although oriental fruit moth may damage green fruit, the fruit is most susceptible to damage after color break. Fruit is most heavily fed upon in the tops of the trees, so fruit samples should be picked and examined from that area.
    Take a fruit damage sample at harvest to assess the effectiveness of the current year's integrated pest management program and determine the needs of next year's program (see Fruit Evaluation at Harvest). Record results for the harvest sample.

    Mating Disruption

    Before applying mating disruption, learn about the various formulations and their durations of effectiveness by closely reading label instructions and getting advice from your pest control adviser. For example, one application of a sprayable formulation is effective for one generation, while aerosol and passive dispensers can cover an entire season. Mating disruption interferes with the mate-seeking behavior of the male moths; therefore, mating disruption pheromone should be applied as soon as moths begin to emerge either in spring or in subsequent generations, depending on whether your selected formulation is targeting one generation or multiple generations.

    Four types of pheromone mating disruption products are available for oriental fruit moth.

    • Sprayable liquid formulations are designed to be applied with standard orchard sprayers and contain pheromones in microcapsules that release pheromones into the air once they are deposited on leaves.
    • Hand-applied passive dispensers of various designs are hung in the orchard at rates ranging from 15 to 250 units per acre. Pheromones are released into the orchard continuously over a prolonged period to cover adults in multiple generations.
    • Aerosol dispensers are hung in the orchard at low densities, typically one to two units per acre. These products mechanically dispense small amounts of pheromones into the orchard air at programmed intervals.
    • Specialized Pheromone and Lure Application Technology (SPLAT) formulations are dollops applied directly to upper portions of the canopy, either manually or mechanically, with customized equipment that typically includes a hopper, pump, and output nozzles. It can be applied from the ground or aircraft.

    Continue using pheromone traps to monitor the emergence of the second flight to get a biofix. Pheromone traps work only when a short-duration sprayable formulation has been applied for the previous generation. When using season-long mating disruption formulations, the biofix can be established by installing traps in nearby almond or peach orchards where mating disruption is not being used. Depending on the duration of effectiveness for each application type, a second application of pheromone may be needed in late July to early August for later-maturing peach varieties. Sprayable pheromones may be used for the first flight or substituted for the second application of pheromone dispensers.

    Depending on the orchard history and seasonal pest density, one or two applications of insecticide may be needed. If a sprayable liquid formulation of pheromone is used, it can be tank-mixed with an insecticide. In orchards with high numbers of the parasitoid, Macrocentrus ancylivorus, frequent insecticide applications may not be necessary. This parasitoid will not be abundant, however, in orchards where a broad-spectrum insecticide has been used.

    Insecticide Applications

    Generally, do not apply insecticide to the first generation, except where numbers are excessive, because variable weather conditions during spring cause erratic emergence and egg laying (oviposition), and insecticides are less effective as a result.

    Once the second flight has started, usually in May, accumulate degree-days. If you plan to apply insecticide with a relatively long-term residual effect (e.g., methoxyfenozide or chlorantraniliprole), treat at 400 DD from the first trapped moth; otherwise, apply insecticides from 500 to 600 DD.

    In orchards with heavy infestations (an average of 3 shoot strikes per tree or if you find any larvae in the fruit), additional insecticide applications will be needed to treat the succeeding generation and prevent fruit damage at harvest. Sprays must be carefully timed to kill newly hatched larvae before they bore into shoots or fruit. If treatments are needed for the third and fourth flights, spray at 400 to 500 DD after the start of the flight.

    Common name Amount per acre** REI‡ PHI‡
    (Example trade name) (hours) (days)
    Not all registered pesticides are listed. The following are ranked with the pesticides having the greatest IPM value listed first—the most effective and least harmful to natural enemies, honey bees, and the environment are at the top of the table. When choosing a pesticide, consider information relating to air and water quality, resistance management, and the pesticide's properties and application timing. Always read the label of the product being used.
      (Semios OFM Eco, CheckMate Puffer OFM-O)# 1–2 dispensers
      COMMENTS: Place dispensers in upper one-third of the tree canopy with nozzle pointing away from foliage and fruit. Standard application rate is 1 puff every 15 minutes over a maximum of 12 hours per day (5 p.m.–5 a.m.). Check with certifier to determine which products are organically acceptable.
      (Isomate OFM TT)# 100–312 dispensers
      (CideTrak OFM-L Meso)# 18–35 dispensers
      COMMENTS: Place dispensers in upper one-third of the tree canopy and place extra dispensers in trees on the orchard's perimeter. General duration of effectiveness is 90 to 180 days. Replace at the beginning of the second flight or in 3 months for 90-day products, whichever occurs first. Check with certifier to determine which products are organically acceptable.
      (CheckMate OFM-F) 1.32–2.93 fl oz 0
      COMMENTS: Use piston, diaphragm, or centrifugal pumps only. Do not use roller or gear pumps as they will damage the microcapsules. For best results, apply immediately after mixing. Sprayable formulations have short residual activity.
      (SPLAT OFM 30M-1) 14.11–35.27 oz 4
      COMMENTS: Apply SPLAT OFM when the ambient air temperature is above 55°F and below 95°F. SPLAT dollops typically cure within 2 to 3 hours following application, after which time this formulation is rainproof and ultraviolet resistant. Do not apply if rain is expected within 1 to 2 hours of application or the temperature is outside this range.
      (Altacor eVo) 1.5–2.2 oz 4 10
      COMMENTS: Because it affects egg hatch, apply 400 DD after first trap catch. Do not use more than 4.6 oz/acre per year or apply in more than 200 gal water/acre.
      (Intrepid 2F) 10–16 fl oz 4 7
      COMMENTS: Because it affects egg hatch, apply 400 DD after first trap catch. Do not use more than 16 fl oz/acre per application or more than 64 fl oz/acre per year.
      (Delegate WG) 6–7 oz 4 1
      (Imidan 70-W) 2.125–4.25 lb 7 days 14
      (Avaunt eVo) 6 oz 12 14
      COMMENTS: Also controls katydids and small plant bugs. Do not apply in more than 200 gal water/acre.
      (Asana XL) 4.8–14.5 fl oz 12 14
      COMMENTS: The use of esfenvalerate is not recommended on perennial crops because high label rates can cause outbreaks of secondary pests.
      (Entrust)# 1.25–2.5 oz 4 1
      (Success) 4–8 fl oz 4 1
      COMMENTS: Works well as a supplement to a mating disruption program. Do not apply more than 29 fl oz/acre per year of Success or 9 oz/acre per year of Entrust.
      (Sevin XLR Plus) 3–4 qt 12 1
      COMMENTS: May cause increased spider mite problems; best used late in the season. Not recommended for routine use, especially early in the season. Do not apply more than 14 qt/acre per year.
    * Permit required from county agricultural commissioner for purchase or use.
    ** For dilute applications, rate is per 100 gal water to be applied in 300 to 500 gal water/acre, according to label; for concentrate applications, use 80 to 100 gal water/acre, or lower if label allows.
    Restricted entry interval (REI) is the number of hours (unless otherwise noted) from treatment until the treated area can be safely entered without personal protective equipment. Preharvest interval (PHI) is the number of days from treatment to harvest. In some cases, the REI exceeds the PHI. The longer of the two intervals is the minimum time that must elapse before harvest.
    # Acceptable for use on organically grown produce.
    No information.
    1 Group numbers for insecticides and miticides are assigned by the Insecticide Resistance Action Committee (IRAC). Rotate pesticides with a different mode-of-action group number, and do not use products with the same mode-of-action group number more than twice per season to help prevent the development of resistance. For example, the organophosphates have a group number of 1B; insecticides with a 1B group number should be alternated with insecticides that have a group number other than 1B.

    Important Links

    Text Updated: 03/24
    Treatment Table Updated: 03/24