Sap Beetles are small beetles attracted to fermenting, damaged or overripe plant material. On sweet corn they commonly enter ears through damaged husks or exposed tips and feed on kernels, often taking advantage of damage already caused by Corn Earworm, birds or other pests. Several beetles may gather inside an ear, where their feeding can increase decay and contamination. They are often a secondary problem rather than the original cause of the damaged ear.

How to Fix It
Harvest promptly: Pick ripe corn rather than leaving mature ears on the stalk, where they become increasingly attractive to Sap Beetles.
Remove damaged ears: Pick and dispose of badly damaged or rotting ears instead of leaving them in the garden to attract more beetles.
Clean up fallen produce: Remove overripe, fermenting or damaged fruits and vegetables nearby that can serve as breeding and feeding sites.
Control the original damage: Corn Earworm, birds and other pests can create openings that allow Sap Beetles into the ear.
Protect ear tips: Varieties with tight, well-covered husks are less accessible to Sap Beetles.
Don't chase every beetle: If Sap Beetles are only appearing in already damaged ears, concentrate on removing the damaged produce and fixing the pest or injury that opened the ear in the first place.