Bean IPM

Legume ipmPIPE Diagnostic Series

Bruchids or Weevils

Acanthoscelides obtectus, Zabrotes subfasciatus, Callosobruchus

Bruchids (Weevils), Acanthoscelides obtectus, Zabrotes subfasciatus (Fig. 1) are important pests of dry beans in the Americas. Several species of Callosobruchus infest stored tropical legumes worldwide. A. obtectus scatters eggs among stored seeds or infest bean pods in the field, while Z. subfasciatus attaches eggs to seeds. C. maculatus (Fig. 2) attaches its eggs on cowpea seed either in the pod or in storage. Newly hatched larvae (1-2 mm) of all three species then penetrate the seed coat and feed internally.

Factors favoring
  • Presence of previously infested crop debris
  • Lack of crop rotation
  • Poor sanitation of previous legume and weed debris
  • Contaminated seed
  • Susceptible varieties
  • Moderate to high moisture conditions favor slugs
Zabrotes subfasciatus
Figure 1 - Zabrotes subfasciatus
Callosobruchus maculatus
Figure 2 - Callosobruchus maculatus
Additional Resources

H. F. Schwartz and F. B. Peairs, Colorado State University

Photo credits

Courtesy of F. B. Peairs Colorado State University, Clemson University Extension