Stalk Borers

The European stalk borer and the common stalk borer are the two types. They are small 2.5 cm caterpillars, grey, brown and black in colour with a thin white stripe running down their backs an an off-white stripe running along their sides. 

European Stalk Borer (top left)-Marlin E. Rice, Common Stalk Borer (top right)
Adult Common Stalk Borer Moth-UNL

Description
Their heads are black. The adult moth is a whitish grey and has a wing span of only about 3cm. Stalk borers should not be confused with European corn borers as they are only similiar. European corn borers do much more damage since they will also bore into your corn.

Stalk borer lavae (left), Stalk borer larvae (right)-Marlin E. Rice

Lifecycle
These borers are located in southeastern Canada and the eastern United States. They lay their eggs in late summer, early fall in grassy areas and where broad leaf weeds are present. Eggs overwinter in the grass. They hatch in the spring and move over to corn fields. The small larvae feed in the whorls of young corn and as they grow they proceed to hollow out the stems of corn.

Damage on corn (left)-Marlin E. Rice, Damage on corn (right)-Ohio State University

Diet and Damage
The larvae feed on the small whorls of new corn and proceed inside the stalk to feed. Corn is their main diet but they are usually finished feeding by the time the plant has 6 or 7 leaves. Because they live in tall grass, usually only the first 3 or 4 rows are affected.

Control
1) Burn Control
Burn grass areas around the corn patch in early march if you have had bad infestations of stalk borers in the past. If not then I do not recommend burning for fear of killing small animals or beneficials in the area. Just cut the grass low and rake it in a pile to burn later. This will kill the eggs.
2) Weed/Grass control
Keep the grass and weeds to a minimum around fencelines, gardens and pastures. This will ensure the stalk borer cannot lay it’s eggs near your corn.
3) Hand Pick
When corn is young, look inside the whorls and pick out any worms you see and drop them in hot soapy water.