Just inside from harvesting vegetables, I heard yelling from the kitchen. She was staring at a freshly washed cucumber in the sink. Sprouting from it were green projections that were alive and wriggling! This was our introduction to the insect pest with the unique name of pickleworm.
These critters are the larvae of the pickleworm moth (Diaphania nitidalis), which overwinters in Florida and becomes a late summer pest of cucurbits (not only cucumbers, but summer and winter squash, pumpkins, cantaloupe, and watermelons) in Western North Carolina.
Life cycle
Once the moths arrive in our area, they lay eggs on cucurbits, which hatch, go through several larval stages, pupate in the plants’ leaves or in the leaf litter, and become adults in less than a month! This short life cycle means we may see two or even three generations of pickleworms a year.
Damage
The larvae can feed on flowers, leaves, and vines, as well as fruits. Larvae eating blooms can prevent fruit set. Like squash borers (Melittia cucurbitae), in the worst-case scenario, pickleworm larvae feeding on the vines can kill your plants. You may see pickleworm excrement (frass), or simply small holes in your fruits. In both cases, your crop is ruined once the larvae are feeding because the damaged areas with start to rot. According to University of Florida’s John L. Capinera, cantaloupes, with their thick skins, may have external damage called “rindworm.”
Management
- Early planting. Plantings that mature before the moths arrive are likely to escape pickleworm damage.
- Resistant varieties. Some squash varieties that are more resistant: summer squashes Early Prolific Straightneck, Early Yellow Summer Crookneck, and Summer Crookneck; and Butternut 23 winter squash.
- Floating row covers. Using row covers at night can prevent the night-flying moths from egg-laying, while still allowing pollinators to visit the flowers by day.
- Garden clean-up. Removing damaged fruits and vines can prevent further generations in the same gardening season.
Learn more:
Pickleworm, University of Tennessee Publication # W206:
https://extension.tennessee.edu/publications/Documents/W206.pdf
University of Florida Featured Creatures:
https://entnemdept.ifas.ufl.edu/creatures/veg/pickleworm.htm
Insect Management on Cucurbit Vegetables in North Carolina
https://entomology.ces.ncsu.edu/cucurbit-insect-management-in-north-carolina/