Stalk, Vine, and Wood Borers

Borers cause damage by weakening the structure supporting the plant.  They also prevent fluids from moving between roots and leaves.  European corn borer is a common insect pest that tunnels in corn stalks and ears.  This reduces yields as stalks break off or ears fall off.  Lilac, dogwood, and rhododendron borers (caterpillars of clearwing moths) frequently weaken or kill host plants.

A similar insect tunnels into squash stems, killing portions of the vine.  Sometimes a vine can be rescued if the borer is removed and the damaged part of the vine covered with soil.

Flatheaded and roundheaded wood borers (beetle larvae) attack apple, poplar, locust, and other trees, especially unhealthy ones or trees under stress.  Bronze birch borers persistently kill white bark birch trees planted as ornamentals.

To reduce problems caused by wood-boring insects, maintain the health and vigor of trees.  Wrap young transplants with a high-quality tree wrap.  Spray tree bark, squash plants, and sweet corn when adults are laying eggs.  Use a yard and garden insecticide labeled for controlling plant boring insects.