WNC Orchard Insect Populations for July 23, 2018

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JApple maggot fly adultuly 23, 2018

Based on degree-day accumulations and pheromone trap captures in non-managed orchards, codling moth and oriental fruit moth both remain active in the mountains (Henderson County), but populations appear to be low in many managed orchards. In most situations, a single insecticide application targeting codling moth will likely be sufficient, but all decisions should be based on trap captures in individual orchards.

As noted last week, first generation brown marmorated stink bug (BMSB) adults are active in lower elevation orchards including Burke, Lincoln, and Cleveland Counties. In those orchards with a history of BMSB damage, insecticide sprays should be applied at this time. This would include products containing pyrethroids or Venom/Scorpion.

In higher elevation orchards (e.g., Henderson County), the BMSB degree-day development model is predicting first generation adults to begin emerging later this week. In fact there was a slight uptick in pheromone trap captures this week, suggesting some emergence has started. To avoid damage on the most susceptible cultivars, insecticides targeting BMSB should begin at your next sprays.

Finally, there was large emergence of apple maggot in our abandoned site in Henderson County this week, with 23 flies captured. Apple maggot emergence times can vary considerably within a region due to microclimate effects, but for those growers not trapping and unsure of maggot activity in their orchards, an insecticide effective against this pest should be made at this time. Pyrethroids applied for BMSB will also provide protection against apple maggot. If not applying a pyrethroid for BMSB, imidacloprid (Admire or generic products) will control apple maggot.

Learn more about southeastern apple insect pests at the Apple Insect Management page.

2018 Average Weekly Trap Captures*

Insects per trap
July 9
July 16
July 23
Codling Moth 1.0 4.8 2.5
Oriental Fruit Moth 11.0 34.0 23.0
Tufted Apple Bud Moth 0.0 1.0 6.0
Redbanded Leafroller 0.0 0.0 0.0
Obliquebanded Leafroller 0.0 0.0 1.0
Lesser Appleworm 0.0 0.0 2.0
Apple Maggot 0.0 0.0 7.7
Brown Marmorated Stink Bug (commercial – mountains) 0.2 0.5 0.7
Brown Marmorated Stink Bug (commercial – upper piedmont) 2.2 4.3 2.8
Brown Marmorated Stink Bug (research – unsprayed) 0.8 0.8 0.5
Spotted Tentiform Leafminer 0.0 0.0 14.0
Dogwood Borer 23.0 51.0 4.0
Peachtree Borer 37.0 37.5 65.0
Lesser Peachtree Borer 4.0 13.0 10.0
San Jose Scale 17.5 70.0 0.0

*Note that averages presented here are intended only to illustrate the timing of insect emergence and fluctuations in population activity, and not as general indicators of population levels. Some orchards included in these averages have significantly higher or lower populations than most commercial orchards in the area, resulting in averages that are sometimes skewed from what is typical. The only way to have an accurate assessment of an individual orchard’s populations is to set up traps in that orchard.

2018 Accumulated Degree Days

  Henderson County
 Biofix July 10
July 17
July 24
Codling Moth Apr 30 1488 1661 1819
Oriental Fruit Moth Apr 2 2071 2280 2473
Tufted Apple Bud Moth May 4 1752 1960 2154
About degree-day models: The degree day (DD) models predict adult emergence and egg hatch of each generation. They do not predict the intensity of populations, which can be assessed by using pheromone traps. Hence, the models should be used to help gauge the time period when control is most likely needed, and pheromone traps provide information on the need for and frequency of insecticide applications. For full details, read “IPM Practices for Selected Pests” in the Orchard Management Guide.


  • 1st generation: Egg hatch begins at about 350 DD after biofix and is completed by 1050 DD. The most critical period for insecticidal control is from 350 to about 750 DD.
  • 2nd generation: Egg hatch of the second generation can extend from about 1300 to 2600 DD after biofix, but the most critical period for insecticidal control is 1400 to about 2500 DD.
  • 3rd generation: Adults begin to emerge at about 2500 DD after biofix, but the model is less accurate in predicting late-season populations.


  • 1st generation: Only one insecticide application between 400 and 500 degree days is usually necessary, as 1st generation egg-laying is usually low on apple.
  • 2nd generation: Effective 1st-generation control may eliminate the need for 2nd-generation control. If trap captures remain high, insecticides may be needed around 1100 to 1400 DD.
  • 3rd generation: Insecticide may be needed at 2200 DD after biofix.
  • 4th generation: Overlapping generations late in the season make it difficult to predict when 4th-generation egg hatch begins, but continuous egg-laying can occur from August through October. Use traps to determine the need for further insecticide applications.


  • 1st generation: One well-timed insecticide application between 800 and 1200 DD after biofix will often eliminate the need for further control of TABM.
  • 2nd generation: Only if trap captures exceed 25 moths per trap by 2600 DD is an insecticide application recommended. NOTE: Insecticides targeting 2nd generation TABM are usually not necessary if 1st generation populations were successfully controlled.