Pest profile

Grape Root Borer

Vitacea polistiformis · Lepidoptera: Sesiidae[2]

Grape root borer larvae feed on grapevine roots below ground, so damage often goes unnoticed until vines decline.[1]

Grape root borer moth, a brown wasp-like moth with thin yellow bands on the abdomen, on a leaf
Grape root borer moth, a brown wasp-like moth with thin yellow bands on the abdomen, on a leaf. Photo: Brighton Lee, public domain (CC0), via iNaturalist

How to identify it

  • Adults are brown moths with thin yellow abdominal bands that resemble paper wasps; front wings are brown, hind wings clear.[1]
  • Larvae are cream-colored, up to 1 1/2 inches, with a retractable brown head.[1]

Look-alikes

Look-alikeHow to tell them apart
Paper waspsThe moth resembles some paper wasps, and males even fly like wasps.[1]

Where it lives

UK Extension calls it potentially the most destructive insect attacking grapes in Kentucky.[1]

US map: public records from 28 states since 1990 (GBIF).

Biology and life cycle

Moths fly from July through early August; females lay about 350 eggs on soil, leaves and weeds.[1]

Larvae spend about 22 months feeding in roots, completing the cycle in two years.[1]

Damage and signs

  • Vines show poor growth and fruit set and can die; several borers can girdle the whole root system.[1]

Health risk

It feeds on plants; UK Extension mentions no risk to people.[1]

Control

Prevention

In midsummer, check within 18 inches of vine bases for empty pupal skins; act if more than 5 percent of vines have them.[1]

Pesticides

Treat only if necessary, timing a coarse spray around the vine base to when adults begin emerging.[1]

Common questions

Why are my grapevines declining?
Grape root borer larvae in the roots are one cause, often unnoticed until decline.[1]
How do I know if I have grape root borer?
Look for empty pupal skins sticking out of the soil near vine bases in midsummer.[1]

Sources

  1. University of Kentucky Entomology (ENTFACT), “Grape Root Borer (ENTFACT-220).” entomology.mgcafe.uky.edu/ef220 (accessed 2026-10-06)
  2. iNaturalist, “Vitacea polistiformis taxon page (order and family).” www.inaturalist.org/taxa/178669 (accessed 2026-10-06)

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