Corn: Seedcorn Beetle

Excerpt from Agronomy Guide for Field Crops (Chapter 3)

Table of Contents

1. Description
2. Life History
3. Damage
4. Scouting Techniques
5. Action Threshold
6. Management Strategies
7. Updates on Corn: Seedcorn Beetle
8. Related links...

Description

Seedcorn beetles are small, brown ground beetles, less than 1 cm (1/3 in.) long, that are primarily predators of small insects but may feed on the germinating corn seeds under slow emergence.

Beneficial ground beetles look very similar to seedcorn beetles but are usually larger.

Life History

This pest overwinters as adults in the soil. In May, the beetles become active, feed, mate and lay eggs in the soil. There are two generations per year.

Damage

The adult is the damaging stage. Damage is confined to the endosperm of the seed and is usually a problem in cool, wet springs when germination is delayed. Adults hollow out the seeds, preventing germination. Emergence of corn up to the 3-leaf stage is the critical time for damage to occur. Damage is most likely to occur in a situation where weather or soil conditions have delayed seed development. Seedcorn beetles are more commonly found on heavy, moist soil, under reduced tillage with excessive residue cover.

Scouting Technique

Adult beetles are present at the time of seed germination. Dig up unhealthy plants or skips in emergence and examine the seed. Examine 10 seeds or sites in five areas to determine the extent of the problem.

Action Threshold

Replanting may be necessary if skips at proper germination time are extensive.

Management Strategies

See OMAFRA Publication 812, Field Crop Protection Guide, for chemical control options. Planting into warmer soils will reduce chances for seed corn beetles to cause damage. (Order OMAFRA Publication 812)

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Updates on Corn: Seedcorn Beetle

• Field Crop Protection Guide - Publication 812
  • Corn: Seedcorn Beetle

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Related links...

• Insects
• Corn

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