Mexican Bean Beetle


Mexican Bean Beetle

Mexican bean beetle adult and larvae

University of Kentucky Dept. Entomology

The adult Mexican bean beetle is rounded in shape, about 5/16 inch long and 1/5 inch wide. Orange-brown to copper in color, they have 16 black spots on their backs. Larvae are oval in shape and yellow with branched spines.


All stages of the Mexican been beetle feed on beans. Young larvae feed on the underside of the leaves. Older larvae and adults eat through the leaf, leaving only the major veins. This type of feeding gives the leaves a lacy appearance. Mexican bean beetles can feed on pods, but rarely damage the developing beans.

IPM Techniques and Scouting

  • When scouting seedlings, look for adults feeding.
  • When plants are taller, use the shake cloth method.
  • Note the number of beetles per 4 feet of row observed at each scouting site. The number of sites you need to examine in a field is based on the size of the field. You will use the average number of beetles per 4 feet of row to determine if a treatment is needed.

Economic Thresholds for Mexican Bean Beetle

Economic Thresholds for Mexican bean beetle are as follows:

Mexican Bean Beetle Economic Thresholds

Mexican Bean Beetle Activity

Mexican Bean Beetle Activity

Please note: These dates are approximations only. This calendar was constructed using data from Kentucky, USA. These dates may not apply in your area. You may wish to contact your county extension agent or agricultural consultant for information tailored to your locality.

References and Additional Information

  • IPM -3 Kentucky IPM Manual for Soybeans
  • Illinois Field Crop Scouting Manual
  • Purdue University - Field Crops Pest Management Manual
  • Handbook of Soybean Insect Pests by Leon G. Higley and David J. Boethel, Entomological Society of America
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