Potato tuberworm
Egg - The oval egg is about 0.5 mm in length. At first white in color, it becomes yellowish before hatching.
Larva - The larva, upon hatching, is creamy white with a dark brown head. The larva varies from greenish to pink as it matures and just before pupation takes on a purplish cast. The larva is 13 to 19 mm long when fully grown.
Pupa - White at first with green blotches, the spindle-shaped pupa soon turns brown. It is about 8 mm long and enclosed in a flimsy, white, silken cocoon.
Host Plants - The potato tuberworm generally attacks Irish potato foliage and tubers, but will also feed on tobacco, tomato, eggplant, pepper, and jimsonweed.
Damage - The potato tuberworm, also known as the tobacco splitworm, generally attacks potato foliage and tubers. However, if Irish potatoes are stored or planted near tobacco fields, the potato tuberworm may also damage tobacco. The potato tuberworm feeds and tunnels between the upper and lower surfaces of leaves causing papery, grayish blotches which become brownish and very brittle. Tuberworm injury is usually concentrated on the older, lower leaves.
Life History - Potato tuberworms overwinter as larvae or pupae in the soil or in potatoes that are not subjected to freezing temperatures. Most active at dusk and dawn, the weak-flying moths emerge in spring and flutter from plant to plant. Each female deposits, singly, 60 to 200 eggs in 4 days or less. Eggs usually are placed on rough surfaces such as the hairy underside of a leaf. Hatch occurs 3 to 6 days later, depending on temperature. Larvae feed and mature in 7 to 10 days under ideal summer conditions, but take longer at cooler temperatures. When fully grown, larvae leave their hosts and pupate in the soil near the base of plants, in leaf remains, or in some other suitably sheltered site. A new generation of moths emerges in 6 to 9 days. Five or six generations occur each year.