Ear head bug

Calocoris angustatus

The Corn Earhead Bug is a pest of economic concern that primarily attacks corn (maize) during its reproductive phase. It is particularly damaging during the milky stage of grain development, where both nymphs and adults feed on the developing grains. The pest's population density is closely influenced by environmental factors like temperature and humidity, making timely monitoring essential for effective control.

Environmental Influence on Pest Population

• Population declines when:

  • Temperatures fall below 18°C or rise above 32°C

  • Relative humidity drops below 30%

  • (Sharma & Lopez, 1990)

Symptoms of Damage

• Nymphs and adults gather on corn earheads, especially during the milky stage of the grain.

• They suck sap from developing grains, causing:

  • Shrunken grains

  • Blackened appearance

  • Ill-filled or chaffy kernels, leading to reduced grain quality and yield

Identification of the Pest

• Eggs:

  • Blue, cigar-shaped

  • Laid under glumes or between florets

• Nymphs:

  • Slender and green in color

  • Actively feed in groups on earheads

• Adults:

  • Males: Greenish

  • Females: Green with distinct brown margins

Conclusion

Effective management of the Corn Earhead Bug requires timely identification and understanding of favorable environmental conditions. Regular field monitoring, especially during the reproductive stages of corn, can help detect early infestations. Integrated approaches including resistant varieties and biological control can be employed to reduce dependence on chemical treatments.