Pest profile

Sycamore Borer

Synanthedon resplendens · Lepidoptera: Sesiidae[2]

Sycamore borer is a clearwing moth common in sycamore in the southwestern US; sycamores tolerate extensive boring.[1]

Sycamore borer moth, a yellow and black wasp-like clearwing moth, on a leaf
Sycamore borer moth, a yellow and black wasp-like clearwing moth, on a leaf. (c) Don Loarie, some rights reserved (CC BY) — via iNaturalist, CC BY 4.0

How to identify it

  • Males are mostly yellow with a brownish-black head, black body bands and mostly clear wings with orange-yellow edges.[1]
  • Clearwing larvae push sawdust-like frass from tunnels, and empty brownish pupal cases may stick out of the bark.[1]

Look-alikes

Look-alikeHow to tell them apart
Western poplar clearwingAnother clearwing that attacks poplar, birch and willow rather than sycamore.[1]
CarpenterwormIts pupal cases closely resemble those of clearwing moths.[1]

Where it lives

It occurs in the southwestern United States and also infests oak and ceanothus.[1]

US map: public records from 2 states since 1990 (GBIF).

Biology and life cycle

Clearwing adults live about a week; females lay tiny reddish eggs in bark cracks and wounds, and larvae bore inside.[1]

Sycamore borer adults are active mainly from May through July.[1]

Damage and signs

  • Larvae bore under the bark, but sycamores tolerate extensive boring.[1]

Health risk

It feeds on trees; UC IPM mentions no risk to people.[1]

Control

Prevention

Generally no control is recommended for sycamore borer.[1]

Biological control

Commercial insect-killing nematodes injected into tunnels are effective against sycamore borer larvae.[1]

Common questions

What's the sawdust coming out of my sycamore trunk?
Frass pushed from tunnels can mean clearwing larvae such as sycamore borer.[1]
Do I need to treat sycamore borer?
Usually not; UC IPM says sycamores tolerate extensive boring.[1]

Sources

  1. University of California Statewide IPM Program, “Clearwing Moths (Pest Notes).” ipm.ucanr.edu/home-and-landscape/clearwing-moths/ (accessed 2026-10-06)
  2. iNaturalist, “Synanthedon resplendens taxon page (order and family).” www.inaturalist.org/taxa/477420 (accessed 2026-10-06)

Updated 2026-10-14. Built from sourced records. Spot an error? Tell us.