Pest profile

Melonworm

Diaphania hyalinata · Lepidoptera: Crambidae[2]

Melonworm caterpillars strip squash leaves down to the veins and sometimes chew into fruit in Southeastern gardens.[1]

Melonworm moth with pearly white wings bordered in dark brown, resting with wings spread
Melonworm moth with pearly white wings bordered in dark brown, resting with wings spread. Photo: Hugo Hulsberg, public domain (CC0), via iNaturalist

How to identify it

  • Larvae grow to about 0.6 inch, turning pale yellow-green after hatching, and shelter in loose silk under leaves by day.[1]
  • Damaged leaves are left lace-like, with the veins intact.[1]

Where it lives

It winters only in south Florida and perhaps south Texas, arriving in north Florida in June and other Southeastern states in July.[1]

US map: public records from 26 states since 1990 (GBIF).

Biology and life cycle

It completes its life cycle in about 30 days, with up to three generations before cold weather where it migrates.[1]

Damage and signs

  • Larvae mainly eat foliage, leaving lacy leaves; when leaves run out or on less preferred hosts like cantaloupe, they feed on fruit.[1]

Health risk

It feeds on cucurbits; UF/IFAS mentions no risk to people.[1]

Control

Keep them out

Row covers effectively exclude the moths.[1]

Sanitation

Destroy crop residue, which may harbor pupae.[1]

Common questions

Why are my squash leaves lacy?
Melonworm caterpillars skeletonize leaves, leaving only veins.[1]
How do I prevent melonworms?
Use row covers to exclude the moths.[1]

Sources

  1. University of Florida IFAS Extension (Featured Creatures), “Melonworm, Diaphania hyalinata (EENY-163).” edis.ifas.ufl.edu/publication/IN320 (accessed 2026-10-06)
  2. iNaturalist, “Diaphania hyalinata taxon page (order and family).” www.inaturalist.org/taxa/151769 (accessed 2026-10-06)

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