Euonymus webworm causing some damage to burning bush around Grand Rapids, Mich.

Euonymus webworm, known as a serious pest of spindle trees, may also cause some problems on burning bush.

Euonymus webworm, an exotic caterpillar and moth from Europe, has already destroyed nearly all of the spindle trees (Euoymus europea) (Photo 1) in Michigan. Now we are seeing occasional damage to burning bush (EAC), as reported by MSU Extension horticulture educator Rebecca Finneran this week in Grand Rapids, Mich.

Spindle tree
Photo 1. Spindle tree.

On spindle trees, the larvae may drape the entire tree in webbing, causing extensive defoliation (Photos 2 and 3 5, 6). On burning bush, a less preferred host, they may only damage part of the shrub (Photo 4 7). Spot-spraying infested shrubs with any pyrethroid insecticide, Orthene, or Sevin, will stop the caterpillars, which may be finished feeding very soon, anyways.

webworm tent
Photo 2. Euonymus webworm tent.

larvae
Photo 3. Euonymus webworms hanging.

web larvae
Photo 4. Euonymus webworm larvae.

In another two to three weeks, you may see the adult moths, which are quite attractive (Photo 5). If you had a problem this year, plan to scout for Euonymus webworm about 2 – 3 weeks earlier next year (by the DegreeDay calendar).

webworm moth
Photo 5. Euonymus webworm moth

Dr. Smitley’s work is funded in part by MSU’s AgBioResearch.

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