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How to Manage Pests

UC Pest Management Guidelines

Tent-shaped pheromone trap. Placing pheromone lure into wing-type trap.


Pheromone Traps

(Reviewed 5/06, updated 4/09)

In this Guideline:

Pheromone traps are used to monitor the flights of certain pest moths and San Jose scale. Use pheromone traps to monitor San Jose scale, omnivorous leafroller, codling moth, and peach twig borer in all orchards. Only orchards that did not receive a dormant or bloom treatment require peach twig pheromone traps. Codling moth traps are needed only in those few orchards with a history of codling moth infestations.

The information obtained from trap catches can be used to schedule control actions when used in conjunction with degree-day calculations. The traps are used to establish a biofix—an identifiable point in the life cycle of the pest at which you can begin degree-day accumulation or take a management action. For example, the biofix for peach twig borer is the date that the first adult moth of each generation is caught.


  • Place traps in each orchard for which you need to make pest management decisions.
  • Traps should be placed in orchards by the dates indicated in the table below.
  • Use at least 2 traps per block for moths, and 3 or 4 per block for San Jose scale.
  • Distribute the traps uniformly throughout the orchard and use the same locations each year.
  • Place additional traps in hot spots.
  • Hang traps 6 to 8 feet high, 1 to 3 feet inside the canopy in the north quadrant of the tree, in the shade, and at least 5 trees in from the edge of the orchard.
  • Check traps twice a week until the biofix is established; thereafter, check traps weekly.
  • Remove trapped insects from the trap bottom after you count and record the trap catch on a monitoring form (48 KB, PDF).
  • Replace trap bottoms monthly or when they become covered with debris.
  • Follow manufacturer's recommendations for replacing pheromone dispensers.
  • Store pheromone dispenser in a refrigerator or freezer.


Insect pest Trap placement date Importance
San Jose scale Feb 25 Determine biofix; excellent for monitoring beneficials.
omnivorous leafroller February 20 (San Joaquin Valley) Determine biofix to begin degree-day accumulation to predict onset of second flight.
codling moth Soon after bud break or by March 15 To help detect first moth emergence and set biofix for degree-day accumulation to predict egg hatch.
peach twig borer March 20 (San Joaquin Valley) April 1 (Sacramento Valley) Determine biofix for each generation; use degree-days to determine caterpillar monitoring schedule.



[UC Peer Reviewed]

UC IPM Pest Management Guidelines: Plum
UC ANR Publication 3462
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