Corn Billbugs

Symptoms of Corn Billbugs

Holes in corn leaf caused by corn billbug
  • Corn leaves twisted and fail to uncurl because of corn billbugs
  • Rows of oval holes in whorl leaves
  • Small plants may be killed
  • Excessive tillers on surviving plants
  • Injury often more severe in border rows
  • Corn susceptible to injury to the V6 leaf stage  
  • Larvae will tunnel into the base of the plant
Corn billbug damage
Corn injured by southern corn billbug

Pest ID

Key Characteristics

  • All billbugs have their mouthparts at the end of a "snout" or "bill" from which they get their name (see image below)

Corn billbug mouthpart

Related Species

  • Corn billbug damage can be easily confused with wireworm, cutworm, seedcorn maggot, stink bug and seedcorn beetle.

Pest Facts and Impact on Crop

  • There are several species, primarily of the Sphenophorus genus: bluegrass billbug, maize billbug (black), southern corn billbug (brown or gray), clay-colored billbug (tan and cream striped)
  • Importance relatively minor but increasing in no-till or other heavy cover rotations
  • No significant natural enemies known
  • Host range is primarily larger grasses, sedges and rushes
  • Small corn plants may be killed or misshapen by adult feeding
  • Plants to V6 leaf stage may tiller and be deformed
  • Severe infestations have reduced yields up to 40%
  • Damage is most severe in yellow nutsedge-infested fields or along border rows with this weed
Yellow nutsedge

Yellow Nutsedge is recognized as a major host.

Favorable Conditions

  • Poorly drained, organic soils
  • Corn-after-corn fields
  • No-till corn fields
  • Fields infested with yellow nutsedge or grassy perennials with a heavy corm or rootstock

Distribution

  • Billbugs that sometime feed on corn exist across the United States but are more of a problem in the Southeast and the Southern Corn Belt

Common Billbug Species

Southern Corn Billbug

Southern Corn Billbug (photo above)

Maize billbug

Maize Billbug (photo above)

Clay-Colored Billbug

Clay-Colored Billbug (photo above)

Bluegrass Billbug

Bluegrass Billbug (photo above)
(photo by Jeff Hahn, University of Minnesota)

Life Cycle

Corn billbug annual life cycle
  • Adults often leave field in fail and overwinter in protected areas around cornfield
  • Adults crawl, or rarely fly, back into the field; they may play dead when distributed

Management Practices for Corn Billbugs

Transgenic offerings are not available for this pest.

Cultural Controls:

  • Crop rotation with a non-grass crop
  • Early planting with good fertility to grow the seedling rapidly past the susceptible stages
  • Plant strong emerging and fast-growing hybrids
  • Control yellow nutsedge and other weeds
  • Scout susceptible fields for first 3 weeks after emergence

Chemical Controls:

  • At-planting soil insecticide
  • Seed treatment insecticide may reduce pressure
  • Rescue treatments may be used with fair success if fields are scouted shortly after corn emergence

*Photo of billbug larva from Purdue University Extension Service