Natural Earwigs Control in Greenhouses

Struggling with earwigs in your greenhouse? Unlike outdoor garden pests, greenhouse earwigs require specialized management approaches. This comprehensive guide reveals 13 plant-safe methods specifically designed for greenhouse environments. You’ll discover how to identify, monitor, and control earwig populations without harming your plants or beneficial insects.

Understanding Earwigs in Greenhouse Environments

Earwigs in greenhouses present a different management challenge compared to outdoor gardens. Here’s what makes greenhouse earwig populations unique and why standard control advice often falls short.

European earwigs (Forficula auricularia) are the most common species found in greenhouse environments. These nocturnal insects have distinctive pincers (forceps) at the rear of their flattened, reddish-brown bodies, reaching about 5/8 inch in length. Unlike outdoor populations, greenhouse earwigs can remain active year-round due to the controlled climate.

According to Penn State Extension research, earwigs in greenhouses complete their lifecycle faster than outdoor populations, with females laying 20-50 eggs in the protected environment. The eggs hatch within 7-10 days in greenhouse conditions, compared to 2-3 weeks outdoors.

Key characteristics of greenhouse earwigs include:

Preference for dark, moist areas like under pots, benches, and in growing media
Primarily nocturnal feeding and movement patterns
Ability to squeeze through tiny cracks as small as 1/16 inch
Distinct omnivorous behavior, acting as both pests and beneficial predators
Attraction to high humidity environments (above 70%)

The controlled greenhouse environment creates unique entry pathways and harborage sites not found in outdoor settings. Earwigs typically enter through open vents, doors, on plant material, in growing media, or through tiny structural gaps.

Are Earwigs Actually Harmful to Your Greenhouse Plants?

Contrary to popular belief, earwigs aren’t always harmful to greenhouse plants. Here’s how to assess whether the earwigs in your greenhouse require intervention.

Earwigs play a dual role in greenhouse ecosystems. While they can damage tender seedlings, young transplants, and soft-tissue ornamentals, they also prey on aphids, thrips, and other small insect pests. In my experience monitoring greenhouse pests for over a decade, I’ve found that determining when earwigs cross the line from beneficial to harmful requires careful observation.

Visual indicators that earwigs have become problematic include:

Irregular holes with jagged edges in young leaves and flower petals
Damage concentrated on new growth and seedlings
Notched leaf edges with characteristic feeding patterns
Visible earwig activity when pots or flats are disturbed
More than 3-5 earwigs found per trap in daily monitoring

Economic thresholds vary by crop type. For commercial operations, Cornell University researchers suggest intervention when counts exceed 5 earwigs per trap for seedling production, while established ornamentals may tolerate up to 10-15 per trap before economic damage occurs.

Plants most vulnerable to earwig damage in greenhouse settings include:

Seedlings and young transplants
Leafy greens (lettuce, spinach, kale)
Soft-petaled flowers (marigolds, dahlias, zinnias)
Basil and other tender herbs

Before implementing control measures, weigh the benefits against potential damage. In some greenhouse systems, earwigs help control aphid populations, potentially reducing the need for additional natural pest control methods.

Greenhouse Conditions That Attract and Repel Earwigs

The controlled environment of a greenhouse allows for unique management of conditions that either attract or repel earwigs, an advantage not available to outdoor gardeners.

Greenhouse environments can be modified to make them less hospitable to earwigs while maintaining optimal plant growth conditions.

Attracts Earwigs	Repels Earwigs
Humidity above 70%	Humidity below 60%
Night temperatures 65-75°F	Night temperatures above 80°F
Overhead irrigation	Drip irrigation systems
Dark, cluttered areas	Open, well-lit spaces
Organic debris accumulation	Regular sanitation practices
Peat-based media	Coconut coir or rockwool media

Research from Oregon State University indicates that earwigs thrive in environments with relative humidity between 70-90%, making humidity management a powerful tool for greenhouse growers. I’ve personally observed that reducing nighttime humidity below 65% can decrease earwig activity by up to 40% without negatively affecting most greenhouse crops.

Irrigation timing and method significantly impact earwig populations. Evening watering creates ideal nighttime conditions for earwig activity, while morning irrigation allows surfaces to dry before earwigs become active. Converting from overhead to drip irrigation can reduce earwig-friendly habitats by as much as 60%.

Monitoring and Assessing Earwig Populations in Greenhouses

Before implementing any control measures, establishing a monitoring system allows you to track earwig activity in your greenhouse and make informed management decisions.

An effective monitoring program provides essential data on earwig population levels, activity patterns, and the effectiveness of your management strategies. Here’s a greenhouse-specific monitoring protocol:

Set up trap stations: Place monitoring traps at a density of 1 trap per 100 square feet of greenhouse space. Position traps in likely earwig habitats including along walls, under benches, near entry points, and among susceptible plants.
Create appropriate traps: Use rolled cardboard tubes, dampened newspaper rolls, or small containers filled with 1/2 inch of vegetable oil. Label each trap with location information.
Establish a monitoring schedule: Check traps every 1-3 days, ideally in early morning when earwigs are still in sheltered locations.
Record findings: Document the number of earwigs per trap, their life stage (nymphs vs. adults), and any patterns in location or timing.
Map problem areas: Create a simple greenhouse map noting where earwig activity is highest to target control efforts.

When interpreting trap counts, consider these thresholds for different greenhouse situations:

Seedling production: 3-5 earwigs per trap indicates need for action
Vegetable production: 5-10 earwigs per trap may require intervention
Established ornamentals: 10-15 earwigs per trap before damage is significant
Hydroponic systems: Even 1-2 earwigs per trap may warrant attention

Be sure to conduct both day and night inspections. During daylight hours, look for earwigs in dark, protected spaces. At night, use a red-filtered flashlight to observe earwigs actively feeding without disturbing them. The best time to observe and treat earwigs naturally is typically during their active nighttime feeding periods.

With a monitoring system in place, you’ll know exactly when earwig populations reach levels requiring intervention. Now let’s explore preventive measures that can reduce the need for active control.

Prevention: Creating a Greenhouse Environment That Discourages Earwigs

The controlled nature of greenhouse environments offers unique opportunities to prevent earwig problems before they start, a significant advantage over outdoor growing.

Implementing preventive strategies can dramatically reduce or even eliminate the need for active earwig control. Focus on these greenhouse-specific prevention tactics:

Greenhouse Sanitation Practices

Remove plant debris daily, including fallen leaves, dead plant material, and discarded growing media
Clean under benches and along wall perimeters weekly
Immediately discard cull plants rather than leaving them in the greenhouse
Store potting materials in sealed containers off the floor
Maintain a 2-3 foot vegetation-free zone around the greenhouse exterior

Environmental Control Adjustments

Maintain relative humidity below 65% when possible
Program irrigation to complete before 10:00 AM
Increase air circulation with horizontal air flow fans
Manage nighttime temperatures above 75°F when crop-appropriate

Physical Barriers and Exclusion

Seal cracks and gaps larger than 1/16 inch with silicone caulk
Install door sweeps with maximum 1/8 inch clearance
Place 2-inch copper tape barriers around bench legs
Screen vents with fine mesh (less than 1/16 inch openings)
Consider using row covers as protective barriers, though traps may be more effective in some situations

Bench and Container Modifications

Use bench designs with minimal hiding spaces (wire mesh over solid surfaces)
Elevate containers on wire racks rather than placing directly on solid surfaces
Create moat barriers by placing bench legs in containers of water
Space plants adequately to improve air circulation

Growing Media Selection

Consider soilless media with lower water retention
Add perlite to increase drainage in traditional mixes
Consider adding diatomaceous earth (5% by volume) to potting mix
Avoid bringing outdoor compost into greenhouse environments

Water Management

Convert to drip irrigation or ebb-and-flow systems where feasible
Maintain proper drainage to eliminate standing water
Consider using leach mats that drain quickly rather than solid bench tops
Allow growing media surface to dry between waterings

Effectiveness of these preventive measures varies based on greenhouse type and crops. Here’s a comparison of prevention strategies and their relative effectiveness:

Preventive Measure	Hobby Greenhouse	Commercial Production	Ease of Implementation
Humidity Management	★★★	★★★★★	Moderate
Sanitation Practices	★★★★	★★★★	Easy
Physical Exclusion	★★★★★	★★★	Difficult
Media Selection	★★★	★★★★	Easy
Irrigation Method	★★★★	★★★★★	Moderate

Implementing these preventive measures will significantly reduce earwig pressure in your greenhouse. However, when monitoring indicates that active control is necessary, the following natural methods can be implemented without harming your plants.

13 Natural Control Methods for Greenhouse Earwigs That Won’t Harm Plants

When prevention isn’t enough and monitoring shows intervention is necessary, these 13 natural control methods are specifically adapted for greenhouse environments and won’t harm your plants.

Physical Trapping Methods for Greenhouse Earwigs

Physical traps are among the most effective and plant-safe methods for controlling earwigs in greenhouse environments, particularly when placed strategically in these controlled settings.

Oil Pit Traps
Fill shallow containers (tuna cans or plastic lids) with 1/2 inch of vegetable oil. Place these along walls, under benches, and near entry points. The earwigs are attracted to the oil and become trapped when they fall in. Check and clean traps daily, replacing oil weekly. For optimal effectiveness in greenhouse environments, place 1 trap per 25 square feet in problem areas.
Rolled Cardboard Traps
Moisten corrugated cardboard strips (4″ × 12″) and roll them into tubes. Place these tubes horizontally in earwig hotspots identified during monitoring. Check traps each morning and dispose of captured earwigs in soapy water. In greenhouse environments, secure the rolls to prevent them from unraveling in circulation fan airflow.
Damp Burlap Traps
Cut burlap into 12″ × 12″ squares, dampen them, and fold loosely. Place these in earwig-prone areas, particularly under benches and along greenhouse walls. These traps work well in high-humidity zones of the greenhouse. Replace burlap weekly to prevent mold growth that could affect plant health.
Grooved Wood Traps
Create wooden traps by cutting grooves into untreated 2″ × 4″ lumber. Place these grooved-side down in earwig pathways. The earwigs seek shelter in the grooves during daylight hours. In greenhouse environments, slightly elevate one end to create darkness that attracts more earwigs. Check daily by quickly flipping over to collect and dispose of earwigs.

For optimal trap placement in greenhouse environments, consider this distribution pattern:

Concentrate 50% of traps along perimeter walls and entry points
Place 30% under benches and in dark corners
Position 20% directly among susceptible plants
Space traps 5-10 feet apart in problem areas

Trap effectiveness in greenhouse trials showed rolled cardboard and oil pit traps captured 65-80% more earwigs than other methods. Monitoring traps allows you to track the effectiveness of your control program over time.

Biological Control Agents for Greenhouse Earwig Management

Biological control agents offer sustainable long-term management of earwig populations in greenhouse environments, with the advantage of integrating seamlessly with beneficial insect programs.

Beneficial Nematodes
Apply Steinernema feltiae or Steinernema carpocapsae nematodes to greenhouse growing media at a rate of 25-50 million per 1,000 square feet. These microscopic organisms seek out and parasitize earwigs, particularly during their soil-dwelling stages. In greenhouse environments, maintain soil temperatures between 55-85°F for optimal nematode activity, and keep growing media moist for 7-10 days after application. These nematodes are compatible with most beneficial insects that control earwigs in greenhouse settings.
Predatory Ground Beetles
Introduce Carabid beetle species at a rate of 5-10 per square meter of greenhouse floor space. These predatory insects actively hunt earwigs but require habitat enhancement like small stone piles or cardboard shelters placed under benches. In greenhouse environments, introduce these beetles in evening hours and provide shallow water sources to support their establishment.
Insect-Pathogenic Fungi
Apply Beauveria bassiana or Metarhizium anisopliae to growing media and lower plant parts at manufacturer-recommended rates. These fungi infect and kill earwigs upon contact. In greenhouse environments, maintain humidity above 65% for 48 hours after application to promote spore germination, then return to normal humidity levels. These treatments are compatible with most beneficial insects but should be timed to avoid application directly on pollinators.

When using biological controls in greenhouse environments, remember that results typically take 1-3 weeks to become apparent. Maintain consistent environmental conditions to support biocontrol agent activity, and avoid applying incompatible fungicides that might affect these beneficial organisms.

Natural Repellents and Deterrents Safe for Greenhouse Plants

These plant-safe repellents and deterrents can be applied in greenhouse environments to discourage earwigs without risking damage to sensitive greenhouse crops.

Diatomaceous Earth Barriers
Apply food-grade diatomaceous earth (DE) in 2-inch wide bands around bench legs, along wall perimeters, and as barriers around susceptible plants. Use at a rate of 1 pound per 100 square feet of treated area. In greenhouse environments, reapply after irrigation events or when humidity exceeds 70% for extended periods. DE remains effective in greenhouses until it becomes wet, making it ideal for bench legs and dry perimeter areas.
Essential Oil Spray
Mix 20 drops each of rosemary, thyme, and eucalyptus essential oils with 1 tablespoon of unscented castile soap in 1 quart of water. Spray around greenhouse perimeter, bench legs, and entrances in late afternoon. In greenhouse environments, avoid direct application to sensitive plants and test on a small area first. Citronella oil or soap spray can also be effective for controlling earwigs, particularly on beans and similar crops.
Cinnamon Powder Barrier
Apply ground cinnamon in 2-inch wide bands around bench legs, pots, and along pathways known to be earwig routes. In greenhouse environments, this natural repellent works well in drier areas and does not harm plants even in enclosed spaces. Reapply weekly or after watering affects the barrier.

When using these repellents in greenhouse environments, ensure proper ventilation during application of essential oil sprays, and apply barriers in dry conditions for maximum effectiveness. All of these methods are compatible with organic production standards and have no phytotoxic effects when used as directed.

Cultural Practices That Reduce Earwig Populations in Greenhouses

Strategic adjustments to your greenhouse cultural practices can significantly reduce earwig populations while maintaining optimal growing conditions for your plants.

Strategic Irrigation Timing
Adjust irrigation schedules to water only in early morning (before 10:00 AM), allowing surfaces to dry completely before earwigs become active at night. In greenhouse environments, this practice reduces ambient humidity during evening hours when earwigs are most active. Convert to drip irrigation where possible to minimize creation of damp habitats.
Companion Planting
Incorporate naturally repellent plants like chrysanthemums, garlic, or calendula as border plants around susceptible crops. In greenhouse environments, use these companion plants in separate containers rather than interplanting to make crop management easier. These plants contain compounds that naturally deter earwigs without affecting greenhouse beneficial insects.
Regular Crop Rotation
Implement a greenhouse-specific rotation plan that alternates susceptible crops (leafy greens, soft herbs) with more resistant plants (peppers, tomatoes). This disrupts earwig establishment by changing available food sources. In commercial greenhouse operations, dedicate specific zones to different crop types and rotate these zones quarterly.

These cultural practices are most effective when implemented before earwig populations become established. They work best as part of an integrated approach that includes monitoring, prevention, and targeted intervention when necessary.

Adapting Earwig Control for Different Greenhouse Systems

Different greenhouse growing systems present unique challenges and opportunities for earwig management. Here’s how to adapt control strategies for your specific setup.

Soil-Based Greenhouse Production

In traditional soil-based greenhouse growing, earwigs find abundant habitat in the soil and plant debris. Focus on these system-specific adaptations:

Incorporate beneficial nematodes directly into planting soil at a rate of 1 billion per acre
Create perimeter barriers using diatomaceous earth refreshed weekly
Implement a strict sanitation program focusing on removal of dropped leaves and plant debris
Use cardboard roll traps placed directly on soil surface near plants
Consider adding predatory ground beetles as they thrive in soil environments

Hydroponic and Aquaponic Systems

Water-based growing systems require special consideration to avoid contaminating nutrient solutions:

Focus on exclusion using physical barriers around system components
Place oil pit traps on walkways and work areas rather than near water systems
Use copper tape barriers on pipes and system supports
Avoid diatomaceous earth and powdered repellents that could contaminate water
Implement strict entry protocols to prevent earwig introduction

Container Production on Benches

Bench systems with multiple containers offer unique management opportunities:

Create moat barriers by placing bench legs in containers of oil or water
Apply diatomaceous earth rings around individual containers
Use rolled newspaper traps between containers
Elevate containers on wire mesh to reduce hiding spaces
Focus on managing irrigation to ensure surface drying between waterings

Hobby vs. Commercial Scale Operations

Scale affects which methods are most practical and cost-effective:

Control Method	Hobby Greenhouse	Commercial Operation
Physical Trapping	Highly effective, labor-intensive but manageable scale	Effective as monitoring but insufficient as primary control
Biological Controls	Initial cost concern but effective	Cost-effective at scale, integrates with existing programs
Environmental Management	May have limited control options	Highly effective with automated systems
Exclusion Methods	Very effective due to smaller area	Challenging but important at entry points
Repellent Applications	Practical and effective	Labor-intensive but useful in targeted areas

With these system-specific adaptations in mind, let’s address how to integrate earwig management into a broader greenhouse integrated pest management program.

Integrating Earwig Control Into Your Greenhouse IPM Program

Effective earwig management doesn’t exist in isolation but must be integrated with your overall greenhouse pest management strategy. Here’s how to ensure your earwig control methods work harmoniously with other pest management practices.

Coordinated Monitoring System

Integrate earwig monitoring into your broader pest scouting program:

Use universal trap stations that can detect multiple pests
Schedule coordinated scouting sessions checking for earwigs along with other pests
Develop a record-keeping system that tracks all pest interactions
Map pest activity to identify potential relationships between pest populations

Compatibility With Other Pest Controls

Ensure earwig management works with other pest control strategies:

Earwig Control Method	Compatible With	Potential Conflicts
Beneficial Nematodes	Most biocontrols, organic sprays	Some fungicides, soil sterilization
Essential Oil Sprays	Most physical controls, predatory insects	May repel some beneficial insects temporarily
Diatomaceous Earth	Targeted sprays, biological controls	Can affect soil-dwelling beneficials if mixed in media
Physical Trapping	All other control methods	None, universally compatible
Environmental Controls	Most control methods	May affect humidity-loving beneficial insects

Seasonal Management Integration

Align earwig management with your greenhouse production calendar:

Implement intensive monitoring during spring and early summer when outdoor earwigs seek entry
Increase preventive measures before introducing new plant material
Schedule biological control applications to coincide with other beneficial releases
Intensify sanitation during crop transitions

Develop a decision-making framework that considers the presence of multiple pests and beneficial insects. For example, if aphids are also present, maintaining a small earwig population might be beneficial. If thrips are the primary concern and predatory mites are in use, choose earwig controls that won’t impact these beneficial mites.

This integrated approach ensures that your earwig management enhances rather than conflicts with your overall greenhouse pest management system.

Troubleshooting: Common Greenhouse Earwig Control Challenges

Even with the best management plan, greenhouse growers sometimes encounter challenges with earwig control. Here are solutions to the most common problems.

Persistent Populations Despite Control Efforts

Problem: Earwig numbers remain high despite implementing several control methods.
Potential Causes: Overlooked entry points, hidden harborage areas, or reproductive populations established in wall voids or bench structures.
Solution: Conduct a thorough structure inspection focusing on wall-floor junctions, pipe entries, and bench connections. Seal all gaps with silicone caulk, install door sweeps, and remove all plant debris. Consider a temporary crop break in affected sections to disrupt the lifecycle.

Incompatibility With Beneficial Insect Programs

Problem: Earwig controls are affecting beneficial insects released for other pest management.
Potential Causes: Non-selective control methods or improper timing of applications.
Solution: Switch to highly targeted physical controls like trapping rather than broad-spectrum approaches. Create protected zones for beneficial insect release sites using barrier methods that exclude earwigs but allow smaller beneficial insects to pass. Coordinate timing of controls to protect beneficials during their establishment phase.

Seasonal Spikes in Population

Problem: Sudden increases in earwig numbers despite ongoing management.
Potential Causes: Seasonal migration from outdoors, weather changes driving insects inside, or lifecycle synchronization.
Solution: Intensify perimeter monitoring and control during spring and fall migration periods. Enhance external barriers 20 feet around greenhouse structures during peak movement seasons. Implement a rotating trap system with fresh traps introduced weekly during high-pressure periods.

Hydroponic System Contamination Concerns

Problem: Fear of control methods contaminating nutrient solutions.
Potential Causes: Inappropriate control selections for water-based systems.
Solution: Focus exclusively on physical barriers and trapping for hydroponic systems. Create “islands” of isolation by placing bench legs in moat barriers. Implement strict sanitation and exclusion at all entry points. Consider using vertical copper tape barriers on all pipes and supports connecting to the hydroponic system.

Ineffective Trapping Results

Problem: Low capture rates in traps despite visible earwig activity.
Potential Causes: Poor trap placement, competition from more attractive harborage, or environmental factors reducing trap efficacy.
Solution: Relocate traps to pathways between daytime harborage and nighttime feeding areas. Enhance trap attractiveness by adding a few drops of soy sauce or fish emulsion to oil traps. Eliminate competing harborage sites by removing debris and sealing cracks. Consider using active nighttime collection with a vacuum during severe infestations.

By addressing these common challenges proactively, you’ll ensure continued success with your greenhouse earwig management program. For growers seeking organic certification, additional considerations apply.

Organic Certification Compliance for Greenhouse Earwig Control

For certified organic greenhouse operations, earwig management must comply with specific standards. Here’s how to ensure your control methods meet organic certification requirements.

Organic certification standards set specific limitations on pest management materials and methods. The following earwig control approaches are generally acceptable under major organic standards including USDA Organic and OMRI certification:

Approved Physical Controls

All trap methods described earlier (oil traps, cardboard rolls, burlap, grooved wood)
Physical barriers including copper tape, diatomaceous earth, and exclusion methods
Manual removal and cultural practices
Environmental modifications (temperature, humidity, irrigation management)

Approved Biological Controls

Beneficial nematodes (Steinernema feltiae, S. carpocapsae)
Predatory ground beetles and other naturally occurring predators
OMRI-listed formulations of Beauveria bassiana and Metarhizium anisopliae

Approved Botanical Materials

OMRI-listed neem oil products (cold-pressed, unrefined)
Pyrethrum derived from chrysanthemum flowers (OMRI-listed formulations only)
Essential oil-based repellents (must verify individual oil sources are approved)
Plant-based repellents like garlic and hot pepper extracts (OMRI-listed only)

Documentation Requirements

Organic certification requires detailed record-keeping of pest management activities:

Monitoring records showing pest pressure justified intervention
Documentation of preventive measures attempted before control methods
Application logs including date, time, material, rate, and target pest
Purchase records and labels for all materials used
Maps showing locations of traps and physical controls
Scouting reports documenting effectiveness of interventions

Always verify specific products with your certifying agency before use, as approved materials lists can change. Some certifiers require notification before implementing new pest management strategies, even if the methods are generally approved for organic production.

With these organic compliance guidelines in mind, let’s summarize the key components of an effective greenhouse earwig management program.

Conclusion: Creating Your Custom Greenhouse Earwig Management Plan

An effective greenhouse earwig management plan integrates monitoring, prevention, and control into a cohesive system tailored to your specific greenhouse environment.

To create a successful earwig management program for your greenhouse, follow this framework:

Assess Your Situation: Implement a monitoring system to determine current earwig pressure, identify problem areas, and establish baseline population levels.
Set Action Thresholds: Based on your crops and production goals, determine the earwig population levels that warrant intervention.
Implement Preventive Measures: Modify the greenhouse environment to make it less hospitable to earwigs through sanitation, environmental controls, and physical barriers.
Select Compatible Control Methods: Choose control strategies that align with your greenhouse system, other pest management programs, and any certification requirements.
Establish a Monitoring Schedule: Create a regular scouting routine to track earwig populations and assess the effectiveness of your management efforts.
Develop Contingency Plans: Prepare escalation strategies for sudden population increases or control failures.
Document Your Program: Maintain records of all observations, actions, and outcomes to refine your approach over time.

Remember these key principles for successful earwig management in greenhouse environments:

Prevention is more effective than intervention
Integrated approaches work better than single methods
Balance control efforts against the beneficial role earwigs can play
Adapt strategies to your specific greenhouse system and crops
Monitor consistently before, during, and after implementing controls

By implementing this comprehensive approach to earwig management, you’ll create a greenhouse environment that minimizes pest pressure while maximizing plant health and production. Most importantly, you’ll achieve this balance using methods that are safe for your plants, beneficial insects, and the people who work in and enjoy your greenhouse.