Current Western NC Orchard Pest Populations Aug 17, 2015

— Written By and last updated by

We track local insect populations throughout the growing season using a system of traps, temperature-recording devices, and degree-day models. Traps and weather data are checked weekly, with results updated by Tuesday afternoon from April through September. Learn more about southeastern apple pests at the Apple Pest Management page.

Weekly summary

August 17, 2015


Both codling moth and oriental fruit moth pheromone trap captures declined sharply during the past week.

Codling Moth.  Based on degree-day accumulations, the drop in codling moth captures coincides with what is normally the tail end of the second generation flight. This probably represents the end of codling moth activity in Henderson County and elsewhere with similar elevations. While third generation moths cannot be discounted in piedmont locations, this would very likely occur only where damage from previous generations was evident.

Oriental Fruit Moth.  Surprisingly, OFM trap captures also declined during the past week. However, a dip in trap captures in mid to late August is not uncommon and may represent separation of the third and fourth generation. As mentioned in posts in previous weeks, sprayable pheromone is probably the most effective approach to managing late-season OFM. In most situations an application in mid to late August will often provide control through September.

Apple Maggot.  Trap captures in abandoned orchards remained steady at about 10 flies per trap. In most commercial orchards, apple maggot is of greatest concern during the first week or two of enhanced activity in abandoned orchards. Movement of flies from abandoned to commercial orchards often declines in late August and early September. There is usually no need for more than one or two insecticide applications targeting apple maggot.

Brown Marmorated Stink Bug.  The number of adults captured in traps and observed in surveys has appeared to level off or actually decline. This is generally a time when adult numbers begin to rapidly increase in advance of peak densities in early September. Hopefully this lower-than-expected adult population is real and not an aberration.

 Average Weekly Trap Captures*

Insects per trap
Aug 3
Aug 10
Aug 17
Codling Moth
13.7 11.0 4.0
Oriental Fruit Moth
7.0 8.5 3.3
Tufted Apple Bud Moth 3.5 3.0 5.0
Redbanded Leafroller 2.5 1.5 0.0
Obliquebanded Leafroller 2.0 1.0 1.0
Lesser Appleworm 2.0 0.0 0.0
Apple Maggot 4.0 4.5 5.0
Brown Marmorated Stink Bug 0.0 0.5 0.5
Spotted Tentiform Leafminer 18.0 18.0 8.0
Dogwood Borer 40.0 17.0 4.0
Peachtree Borer 52.0 30.5 31.0
Lesser Peachtree Borer 25.0 28.5 57.0
San Jose Scale 367.5 325.0 512.5

*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.

Accumulated Degree Days

Henderson County
 Biofix Aug 3
Aug 10
Aug 17
Codling Moth April 23 2014 2184 2331
Oriental Fruit Moth Apr 6 2734 2936 3116
Tufted Apple Bud Moth April 23 2474 2676 2856
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.