< ScoutInfo


Diseases of  Alfalfa  Corn  Soybeans  Wheat

Insect Pests of  Alfalfa  Corn  Soybeans  Wheat

Weeds  Identify  Monocots  Dicots  Grasses  Sedges  Lilies  Broadleaf

Scout Info
Kentucky IPM Pest Information Pages

Mexican Bean Beetle : Kentucky Soybean IPM

Mexican Bean Beetle


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.

mexican bean beetle


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

Economic Thresholds for Mexican Bean Beetle

Economic Thresholds for Mexican bean beetle are as follows:

Stage of Growth Date Number of Insects per 4 Row Feet Required
to Justify Using Control Measures
seedling June3 or more adults
prebloomJuly20 or more larvae plus adults
bloomJuly-August16 or more larvae or adults
pod setAugust16 or more larvae or adults

Mexican Bean Beetle Activity

Mexican bean beetle activity chart

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

This site was created and is maintained by Pat Dillon, Department of Entomology, University of Kentucky, S-225 Agricultural Science Ctr North, Lexington, KY USA  40546-0091 (phone: 859/257-3571). Please send questions or suggestions to: pdillon@uky.edu