Pest Profile

Alfalfa Caterpillar
Colias eurytheme
  • Alfalfa caterpillar: Green larvae with white and pink band on either side of abdomen, and can have 2 white lines running down the back.
  • Alfalfa caterpillar egg
  • Alfalfa caterpillar butterfly: Strong brown-black spots on near middle, front margin. Pronounced brown-black margin around wings; males having yellow spots within margin. Wingspan of 2-2.5".

Pest Description

Alfalfa caterpillars are larvae of the sulfur butterfly. They are green worms with a white, longitudinal stripe along each side of their bodies. They attain a length of 1/4 to 1/2 inches, and on close inspection appear to have a velvety skin. They are usually held in check by naturally occurring parasites and diseases. Infestations seldom reach economic levels before late summer. Damaging populations are most likely encountered in southwest Kansas fields that stand five or more weeks between cuttings. Control measures are justified when there are 10 worms per sweep of the net, and cutting will not take place during the next few days.


Source of information

J.P. Michaud, KSU Entomology

Pest photo source

J.P. Michaud, KSU Entomology