Potato tuber moth
Potato’s main storage pest and a field pest too — mines the foliage, then bores the tubers, especially exposed ones and those in store.
- Pest type
- Mining/boring caterpillar
- Attacks
- Leaves, stems, tubers
- Worst in
- Storage; exposed tubers
- Main risk
- Tubers riddled and rotting in store
Overview
The potato tuber moth is the most serious pest of stored potatoes in India and also damages the crop in the field. The small moth lays eggs on the leaves and on exposed tubers; the caterpillar first mines the leaves and stems, leaving blotchy tunnels, but its important damage is to the tubers.
The caterpillar bores into tubers — reaching those exposed at the soil surface or through cracks in the field, and continuing to attack them in storage. It tunnels just under the skin and deeper, filling the tuber with dark, frass-packed galleries that invite rot and make it unfit to eat or plant. Losses are usually far worse in poorly-managed storage than in the field, so earthing-up in the field and strict store hygiene are the heart of control.
How to identify it
- Blotchy mines and tunnels in the leaves and stems in the field, and tunnelled, frass-packed tubers.
- Tubers with dark galleries just under the skin and deeper, often with rot spreading from the tunnels.
- Small caterpillars (pinkish-white with a dark head) inside the tubers and mined foliage.
- Damage building up rapidly in warm, poorly-managed storage on exposed or cut tubers.
The damage it does
- Tubers riddled with tunnels and rot, unfit for eating, marketing or seed — the main and often severe loss.
- Heaviest damage in storage, where an infestation brought in from the field multiplies on the stored crop.
- Field damage to foliage (mining) and to tubers exposed at the surface or through soil cracks.
- Loss of seed potato viability, spreading the problem to the next crop.
When to act
- In the field, keep tubers covered — earth up well and repair cracks so egg-laying females cannot reach the tubers.
- At and after harvest, act fast — harvest promptly, do not leave dug tubers exposed in the field overnight, and inspect before storing.
- In storage, monitor with pheromone traps and check the stock regularly, since this is where losses escalate.
Organic & cultural control
- Earth up the crop well and keep the soil surface free of cracks so tubers are never exposed to egg-laying moths — the key field measure.
- Harvest promptly and do not leave harvested tubers exposed in the field; remove and destroy infested tubers before storing.
- Store only sound tubers in a cool, clean store, and cover them with a layer of dry sand, or use a layer of chopped/dried neem or lantana leaves, a traditional deterrent.
- Use pheromone traps in the store for monitoring and mass-trapping, and destroy crop residue and cull piles that harbour the moth.
Chemical control
- In the field, a CIB&RC-registered insecticide for potato foliage pests, plus good earthing-up, protects the crop and tubers.
- For storage, follow recommended practices — cool storage and hygiene are primary; any store treatment must be a registered, safe method for a food commodity.
- Because the tuber is eaten, prioritise cultural and physical control and observe all safety intervals; do not use unapproved chemicals on stored potatoes.
- Confirm the current field and storage recommendations for your area with your local KVK.
Crops most at risk
Where this problem is called out in our crop guides — open a crop for the full package of practices.
Frequently asked questions
My stored potatoes are full of dark tunnels and rotting. What is it?
That is the potato tuber moth, the main storage pest of potato. The caterpillar bores into the tubers, filling them with dark, frass-packed tunnels that bring rot, making them unfit to eat or plant. Losses are usually worst in storage. Store only sound tubers, keep the store cool and clean, cover with dry sand, and use pheromone traps.
How does earthing-up help against tuber moth?
The moth lays its eggs on tubers exposed at the soil surface or reachable through cracks. Earthing up well and keeping the soil surface crack-free keeps the tubers covered, so the moth cannot reach them to lay. This simple field practice is one of the most effective ways to cut tuber-moth damage before the crop even reaches storage.
How do I stop the problem carrying into storage?
Harvest promptly and never leave dug tubers exposed in the field overnight, sort out and destroy infested tubers before storing, and store only sound ones in a cool, clean store — covered with dry sand or with neem/lantana leaves, and monitored with pheromone traps. Most tuber-moth loss happens in poorly-managed storage, so store hygiene is decisive.
Symptoms and control measures follow ICAR, KVK and state agricultural-university package-of-practices; any named chemical is a registered use. Always read the product label and confirm the dose for your crop and zone. editorial policy.