University of Maryland Extension

Potato Tuberworms - Vegetables

tuberworms inside a potato

Back to Common Problems - Vegetables

Potato tuberworms are the larvae of an inconspicuous moth. The adult lays eggs on the foliage, and the larvae mine leaves (feed between leaf surfaces) and bore into stems. Foliar damage is usually minor. Larvae drop to the soil and find their way to poorly covered tubers. They then bore deep tunnels that are usually filled with black fecal material and fungi. Use floating row cover to protect foliage from egg-laying adults. Keep tubers covered by two inches or more of soil to keep larvae from reaching tubers.

Tuberworm overwinters as a pupa in plant residues. Adult moths emerge in the spring and eggs are laid on the undersides of potato leaves (they may also attack other members of this family- tomato, eggplant, pepper). Pink to white larvae reach Ā¾ inch in length and feed between leaf surfaces (leaf mining injury) and tunnel into stems. The larvae then pupate at the base of plants. Later generations of eggs are laid on the eyes of poorly covered potato tubers that larvae tunnel into. The deep tunnels are usually filled with black fecal material and fungi. Hot, dry weather favors this pest.

Management: Incorporate organic matter and use thick heavy mulches to interfere with pest movement and egg laying. Use a floating row cover to protect foliage from egg-laying adults. Keep tubers covered by two inches or more of soil to keep larvae from reaching tubers. Monitor plants for signs of this pest and remove those that are infested. Clean up all plant residues at the end of the season.

Maintained by the IET Department of the College of Agriculture and Natural Resources. © 2017. Web Accessibility