How to identify
The caterpillar is greenish with two thin white stripes running its full length, growing to about 3/4 inch, and it feeds right inside blossoms and young fruit. The adult is a delicate white moth with dark brown wing borders, flying at night to lay eggs on flower buds.
Damage signs
Larvae chew blossoms, bore into young melons and cucumbers, and skeletonize leaves — damaged fruit rots from the entry wound. A few worms can hollow out a whole cluster of baby melons before you notice.
Plants it attacks
Melons, cucumbers, watermelons, squash, pumpkins
Non-chemical controls
- Drape floating row cover over vines from transplant until flowering ends — the night-flying moth can't lay eggs on what it can't reach.
- Handpick caterpillars from blossoms and fruit in the early morning when they're feeding openly; drop them in soapy water.
- Release Trichogramma parasitoid wasps, which hunt down and destroy the moth's eggs before they ever hatch.
- Pick and destroy any bored fruit immediately — one infested melon left on the vine is a nursery for the next generation.
- Till the bed in fall to expose overwintering pupae in the soil to birds and weather.
- Plant early-maturing varieties so your main harvest finishes before moth populations peak in late summer and fall.
Nerdy fact: The melonworm moth lays its eggs at night directly on flower buds, so by the time you see the worm, it has already eaten the appetizer, the entrée, and the melon.