PestMedium Severity

Sycamore Borer

Ramosia resplendens

A clearwing moth that attacks Western sycamore and coast live oak in California. Larvae bore into inner bark creating twisting tunnels, causing bark to slough off. Prefers older trees under drought stress and those with wounds.

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Sycamore borer larvae showing characteristic tunneling damage in sycamore bark

Identification & Symptoms

What to Look For

Sloughing bark that looks like mud on sycamore
Holes with bleeding on oak trees
Small amount of frass on trunk or around holes
Branch dieback
Loose pupal skins exposed at tunnel exits

Potential Damage

Bark sloughing from tunnel damage
Branch dieback and tree decline
Weakening of tree structure
Increased susceptibility to other pests and diseases

Lifecycle

Adults emerge May to early August, laying eggs singly in bark cracks or depressions, favoring wounds. Larvae bore into inner bark making tortuous tunnels, feeding most of winter. Pupate in early spring near tunnel exits.

Professional Treatment Approach

1

Remove and destroy infested bark where possible

2

Improve tree vigor through proper watering and care

3

Avoid wounding trees during vulnerable periods

4

Preventive insecticide treatments in spring

5

Maintain proper tree health to resist attack

Recommended Mauget Products

Imicide

Professional-grade treatment specifically effective against sycamore borer.

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Tree-äge

Professional-grade treatment specifically effective against sycamore borer.

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Need Professional Diagnosis?

Our certified arborists can help you accurately identify tree problems and develop an effective treatment plan using Mauget's proven injection systems.

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