Tuberworms are a very small worm (1cm), light coloured with a dark head. Adult moths are very small (1.5 cm) and are greyish white. They are slim with long bodies. 

Potato Tuberworm Larva-J. Linduska (left), Potato Tuberworm Adult Moth (right)-Jack Kelly Clark, University of California

Description
Eggs are very small, white or yellowish coloured and laid on the leaves of the host. Pupae are whitish coloured and about 8mm long.

Lifecycle-North Carolina University

Habitat and Lifecycle
They are found worldwide in warmer climates. There can be more than one generation per year. They overwinter as larvae or pupae in the soil or in the potatoes themselves. Areas where freezing occurs should kill off most of the larvae/pupae. Adults emerge in the spring and can lay up to 100 eggs on the undersides of leaves. Eggs hatch in less than a week. Larvae feed for up to two weeks, pupate in the soil and emerge again in a week to 10 days.

Damage-Jack Kelly Clark, University of California

Diet and Damage
Potatoes, tomatoes, eggplant and tobacco are susceptible crops. This is usually more of a problem in large farms. Plants will become stunted from leaf and stem mining. The larvae also bore into tubers and damage young potatoes. They enter at eyes and their tunnels become black with excrement. Wireworm tunneling is white so you will know which kind you have.

Control
1) Plant Potatoes Deeply
Tuberworms do not infest tubers deep in the ground.
2) Avoid underwatering
Underwatering can cause cracks in the soil where the larvae is able to enter.
3) Pheromone Traps
Pheromones can be purchased at local nurseries & greenhouse. Place a trap in a pan of water with dish soap and cover with a tent. It will attract adults and they will die. Of course this is not a solution to the whole problem. Hand picking the larvae is the best method.
4) Destroy Volunteer Potatoes
Volunteer potatoes are an attractant to the pest as they generally are much earlier than regular seedlings. The worms can gain a foothold and reduce your new crops