Stem & Wood Borers
Various (Coleoptera & Lepidoptera)
Borers, Mining & Weevils Insects Severe Risk 10-35 mm (larvae)
📖 Description
Borers are among the most destructive and difficult-to-control plant pests because they feed hidden inside plant stems and trunks. By the time symptoms appear, significant internal damage has already occurred. The larvae tunnel through plant tissue, disrupting water and nutrient transport, which leads to wilting, dieback, and eventually plant death. Emerald ash borer, peach tree borer, and squash vine borer are among the most notorious species, collectively causing billions of dollars in damage annually.
⚠️ Symptoms to watch for
- Small round or D-shaped exit holes in bark or stems
- Sawdust-like frass at base of plant or in bark crevices
- Wilting and dieback of branches or entire plant
- Bark cracking or peeling in affected areas
- Galleries under bark when bark is peeled back
- Sudden collapse of otherwise healthy-looking stems
🩹 Treatment
- Remove and destroy severely infested branches or plants (organic)
- Insert nematode solution into borer holes (organic)
- Apply beneficial nematodes (Steinernema) to soil and bark (organic)
- Use pheromone traps to monitor adult emergence (organic)
- Apply systemic dinotefuran as soil drench or trunk injection (chemical)
- Spray permethrin on bark during egg-laying period (chemical)
🌿 Organic treatments
- Remove and destroy severely infested branches or plants
- Insert nematode solution into borer holes
- Apply beneficial nematodes (Steinernema) to soil and bark
- Use pheromone traps to monitor adult emergence
🧪 Chemical treatments
- Apply systemic dinotefuran as soil drench or trunk injection
- Spray permethrin on bark during egg-laying period
🛡️ Prevention
- Maintain tree health with proper watering and fertilizing
- Avoid pruning wounds during adult flight season
- Protect tree trunks from mechanical injury
- Use tree wraps on young trees to prevent egg-laying
- Remove and destroy infested wood before adults emerge
- Choose resistant varieties and species for your area
🪴 Affected plants
- Fruit Trees
- Birch Trees
- Ash Trees
- Dogwood
- Squash
- Raspberries
- Tomatoes
🦋 Natural predators
- Various beneficial insects
🌱 Host plants
- Various plants
🔄 Lifecycle
- Adults emerge from host plants in spring or summer, mate, and lay eggs on bark or stems.
- Eggs hatch in 1-2 weeks.
- Larvae bore into the plant and feed internally for months to years depending on species.
- Some species complete development in one year, while others take 2-3 years.
- Pupation occurs within the plant or in soil.
- Most species have one generation per year.
📅 Season
- Spring to Fall (larvae feed year-round inside plants)
🔎 Appearance
- Larvae are cream-colored, legless grubs with brown heads.
- Adults are various beetles or moths depending on species.
- Entry holes and frass are the most visible signs.
💥 Damage level
- Severe
🔁 Reproduction rate
- Moderate
🗺️ Geographic regions
- North America
- Europe
Have an Insect to Identify?
Upload or take a photo of an insect on your plant and our AI will identify it and recommend treatments.
📷 Diagnose from Image