Pest profile

Potato Tuberworm

Phthorimaea operculella · Lepidoptera: Gelechiidae[2]

Potato tuberworm larvae tunnel into potato tubers, stalks and leaves, and in tomatoes they bore into fruit and stem tips.[1]

Potato tuberworm moth, a small narrow-winged gray-brown moth with long antennae, resting on a leaf
Potato tuberworm moth, a small narrow-winged gray-brown moth with long antennae, resting on a leaf. (c) ingridaltmann, some rights reserved (CC BY) — via iNaturalist, CC BY 4.0

How to identify it

  • Larvae are dull white to pinkish with dark heads and never grow longer than about 1/2 inch.[1]
  • In potatoes, tuber eyes turn pink with excrement and silk.[1]

Look-alikes

Look-alikeHow to tell them apart
Tomato pinwormPinworms are gray to yellowish with red or purple around each segment, lack the dark head, and attack only tomatoes.[1]

Where it lives

UC IPM covers it as a garden pest of potatoes, tomatoes, eggplant and peppers in California.[1]

US map: public records from 12 states since 1990 (GBIF).

Biology and life cycle

Moths lay eggs on tubers, foliage, plant debris or soil and crawl through soil cracks to reach tubers.[1]

Larvae tunnel into fruit, stalks or leaves.[1]

Damage and signs

  • In tomatoes they bore into fruit and kill stem tips; in potatoes they tunnel through tubers, stalks and leaves.[1]

Health risk

It feeds on plants and tubers; UC IPM mentions no risk to people.[1]

Control

Prevention

Don't plant tomatoes, eggplant or peppers near infested potatoes or right after a potato crop.[1]

Keep them out

Keep potatoes deeply hilled, don't let the soil crack, and use sprinklers to keep the surface sealed.[1]

Sanitation

Harvest promptly and destroy infested tubers, or store them below 52 degrees F to stop development.[1]

Common questions

Why do my potatoes have pinkish eyes and tunnels?
Potato tuberworm larvae leave excrement and silk at tuber eyes and tunnel inside.[1]
Is it the same as tomato pinworm?
No. Tuberworms have dark heads and attack potatoes; pinworms attack only tomatoes.[1]

Sources

  1. University of California Statewide IPM Program, “Potato Tuberworm (Pests in Gardens and Landscapes).” ipm.ucanr.edu/PMG/GARDEN/VEGES/PESTS/pottuberwrm.html (accessed 2026-10-06)
  2. iNaturalist, “Phthorimaea operculella taxon page (order and family).” www.inaturalist.org/taxa/395129 (accessed 2026-10-06)

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