Painted Lady Butterfly (Thistle Caterpillar) Occasionally economic numbers of Painted Lady Butterflies occur in the state. There are many infestations throughout the state. They strip the leaves off the Canada thistle and leave the stem and midrib. This will only temporarily set back the weeds. New growth will likely develop in the fall. The Painted Lady Butterfly has around four generations per year and can be around for a while. This species also has sixty to seventy different plants that they can attack. It's favorite is Canada thistle. After they are gone, they can move to sunflowers, soybeans and other crops. They are hardy eaters, so keep monitoring your fields. We had a large outbreak in 1982 and many sunflower fields had to be treated. Asana can be used at the lower rate for both soybeans and sunflowers or Pounce and Ambush can also be used on soybeans. (See label for newest information). For more information see the Field Crop Insect Management Guide at http://www.ext.nodak.edu/extpubs/plantsci/pests/e1143w1.htm Back to Insects Menu
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