Wigging out, then wigging in: removing earwigs from stone fruit and augmenting them in pome fruit

Project Overview

Project Type: Research and Education
Funds awarded in 2020: $348,733.00
Projected End Date: 12/31/2023
Host Institution Award ID: G361-20-W7899
Grant Recipients: USDA-ARS; Washington State University; Oregon State University; M3 Consulting
Region: Western
State: Washington
Principal Investigator:
Rick Hilton
Oregon State University
Nathan Moses-Gonzales
M3 Consulting Group
Dr. Louis Nottingham
Washington State University
Dr. Ashley Thompson
Oregon State University
Dr. Northfield Tobin
Washington State University


  • Fruits: apples, apricots, cherries, peaches, pears


  • Education and Training: extension, on-farm/ranch research
  • Pest Management: biological control, traps

    Proposal abstract:

    Current research indicates that earwigs are critical natural enemies of aphids, pear psylla, and codling moth. However, the role of earwigs in controlling orchard pests has been unappreciated, likely because previous pesticide programs were too harsh for earwigs to thrive. Growers that recently converted to softer programs have been unable to use earwig biological control because their populations have been eliminated; earwigs have long generation times and poor dispersal ability, which inhibits their reestablishment. This project will develop tactics that growers can use to inoculate their orchards with earwigs. Earwigs are particularly good candidates for inoculation because they are omnivorous and poor dispersers, so they often remain in orchards feeding on alternative food when pest populations are low. This is in contrast to other natural enemies (e.g. ladybeetles and lacewings) that readily move out of orchards after release, especially if prey populations are low. We will create a mass-trapping protocol for earwigs to support releases in pome fruit by determining (a) the most effective mass trap and (b) whether these traps can be used to reduce damage in stone fruit, where earwigs are pests. The project will examine the potential of earwig augmentation in pome fruit by (a) confirming that earwigs do not damage pears or ‘Honeycrisp’ apples, (b) determining optimal earwig release rates and timings for establishment, (c) examining efficacy of using earwig shelters to increase earwig populations, and (d) testing the potential of drones as a more efficient method of earwig release. We will also screen pesticide non-target effects on earwigs so growers can make spray choices that minimize harm to biocontrol agents. We will improve stakeholder knowledge regarding earwig IPM by (a) summarizing research findings at grower meetings, (b) conducting field days on collaborating grower farms, and (c) creating extension documents and (d) a multimedia library describing earwig biology and management. Our project will reduce orchardist reliance on insecticides to manage pests, decreasing pesticide exposure of workers, consumers, and the environment.

    Project objectives from proposal:

    1. Develop a mass trapping protocol for earwigs to support releases in pome fruit by removing them from stone fruit orchards where they are pests. (Years 1-2)

    a. Determine which trap type catches the largest number of earwigs in stone fruit orchards

    b. Measure success of earwig mass trapping in stone fruit orchards

    2. Examine potential of earwig augmentation in pome fruit.

    a. Determine if earwigs cause damage to pears or to ‘Honeycrisp’ or ‘Gala’ apples (Year 1)

    b. Determine optimal release rates and timing to establish augmented earwigs (Years 1-3)

    c. Examine the efficacy of adding shelters to increase abundance of existing earwig populations (Years 2-3)

    d. Test potential of using drones to release earwigs (Years 2-3)

    3. Screen non-target effects of pesticides on earwigs. (Years 2-3)

    a. Determine acute short-term toxicity of organic and conventional tree fruit pesticides to earwigs

    b. Examine sublethal effects of pesticides on earwig motor coordination and predation

    4. Improve stakeholder knowledge on earwig IPM.

    a. Summarize research findings at grower meetings (Years 2-3)

    b. Conduct field days on collaborating grower farms to demonstrate earwig monitoring and effects on pest populations (Year 2)

    c. Create widely available extension documents describing earwig biology, monitoring, and augmentation (Years 1-3)

    d. Create an online video and photo library to convey project results and demonstrate earwig trapping and augmentation (Years 1-3)

    e. Measure changes in grower knowledge with surveys throughout the project (Years 1-3)

    Any opinions, findings, conclusions, or recommendations expressed in this publication are those of the author(s) and do not necessarily reflect the view of the U.S. Department of Agriculture or SARE.