Stop Western Yellowstriped Armyworm – Now in the North Okanagan

Williams Lake - September 5, 2019.  The Invasive Species Council of BC is calling on the public and producers in the North Okanagan to be on alert for the Western Yellowstriped Armyworm (Spodoptera praefica).   The Western yellowstriped armyworm is an invasive caterpillar first detected in the North Okanagan Valley of BC in July 2018.  This pest causes extensive damage to forage crops, vegetables, flower gardens and ornamentals, often resulting in complete defoliation. The Western yellowstriped armyworm can be spread within infested hay, produce, on farm equipment and vehicles. It has not yet been observed within other parts of Interior BC and Coastal BC. 

How to stop the spread

  • Be on the lookout for black caterpillars, up to 5cm long, with distinct pale yellow stripes down the body. 
  • Do not move hay bales immediately after cutting; caterpillars take refuge beneath swaths or bales
  • Store bales for 1-3 weeks to allow caterpillars to move out or die
  • Inspect hay for caterpillars before transporting or selling
  • Inspect purchased hay before unloading
  • Clean equipment and vehicles when moving between farms

Report suspects

Report suspect Western yellowstriped armyworms or damage within new regions of BC to the BC Ministry of Agriculture contacts below:

Learn more

Read more about Western yellowstriped armyworm.

About the Invasive Species Council of BC

The Invasive Species Council of BC (ISCBC) is working to minimize the negative ecological, social and economic impacts caused by the introduction, establishment, and spread of invasive species for more than 10 years. Their goals are to: educate the public and professionals about invasive species and their risks to ecosystems and economies through activities such as workshops, seminars and newsletters; coordinate research relating to invasive species and make this available to the public; and undertake and support actions that improve the health of BC’s natural ecosystems. For more information visit

Media contact: 

Gail Wallin

Executive Director, Invasive Species Council of BC | 250-305-9161

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Fax: 778-412-2248

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