European Corn Borer on Vegetables

Life cycle/habits

• Overwinter in stalks as mature larvae.
• In spring, pupate and emerge as moths. 
• Egg-laying occurs in May-June and again in July-August on leaf undersides. 
• Larvae feed on leaves and developing corn tassels.
• As tassels emerge, larvae bore into stalk or husk at ear tip, side, or base.
• Usually 2-3 generations a year. 

Host plants

• Corn.
• Can be a significant pest on pepper fruit.
• Secondary pest on foliage or fruit of beans, celery, cowpea, potato, rhubarb, spinach, and tomato, among others.

Signs/symptoms

• Borers make pinhole entrances, exuding sawdust-like frass.
• Foliage above bored stems may wilt or break.
• Borers enter peppers near the stem and feed on seed core.
• In young corn shoots, feeding occurs in the central whorl of leaves and silk.
• Older larvae do the most damage, on sweet corn boring into and feeding primarily in the ear and introducing fungi.
• Ears will have chewed tips and kernels, with tunneling along rows of kernels and into the cob.

Monitoring

• For young corn plants, inspect leaves for eggs masses.
• Later look carefully into the whorl for developing larvae.
• Pinhole entrance holes will be visible on stalks and fruit or corn husks.

Prevention/control

• Manage corn borers by destroying stalks, the overwintering site of larvae. Cut off stalks close to the soil. Till under, shred, or remove stalks from the area.
• Bt, an "organic" microbial insecticide can be sprayed when larvae first appear.
• You can split infested stalks below the borer holes and then destroy this pest by poking it with a piece of wire or a nail.