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Department of Entomology

Department of Entomology
123 W. Waters Hall
1603 Old Claflin Place
Kansas State University
Manhattan KS 66506-4004

785-532-6232 fax

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Alfalfa Insects

Fall Armyworm, Spodoptera frugiperda.


Egg mass showing covering of anal hairs.


Larva of fall armyworm showing distinctive striping and unique head capsule coloration with inverted 'Y'.


Male and female adult moths.

Infestations of fall armyworm are most likely to occur in late summer to early fall before frost (September – October). One to two worms per square foot can destroy seedling alfalfa, and populations of 10 to 15 per square foot have been observed to destroy 12- to 14-inch alfalfa. This is a migratory pest that does not overwinter in Kansas.

Please refer to the most recent version of the Alfalfa Insect Management Guide for specific control alternatives.

Page last updated 10/29/2013 by J.P. Michaud.