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Corn Billbugs

 
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Corn Billbugs

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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

 

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 fall and overwinter in protected areas around cornfield
  • Adults crawl, or rarely fly, back into the field; they may play dead when disturbed

 

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

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