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Featured Pest - the White Cabbage Butterfly

Let's talk about a pest that we regularly encounter in our gardens in the summer.




Although this unsuspecting pollinator may look beautiful, it's actually quite the destructive pest.









Figure 1. Anderson, K. (2017). White Cabbage Butterfly collecting nectar from a Calendula blossom. [Photograph]. Eagle Creek Farms, Red Deer County, Alberta, Canada.


The White Cabbage Butterfly, also known by it's scientific name, Pieris rapae, is a pest that targets crops in the Brassicaceae (Cabbage) family. This means that all Brassica crops are susceptible to damage by this pesky little insect. Affected crops include cabbage, kale, broccoli, cauliflower, Brussel sprouts, and bok choy, to name a few.




Figure 2. Anderson, K. (2021). White Cabbage Butterfly laying (ovipositing) eggs on the undersides of kale leaves. [Photograph]. Okotoks, Alberta, Canada.




The White Cabbage Butterfly females lay their eggs (oviposit) on the undersides of leaves . The eggs are tiny, bullet shaped and range anywhere from pale to intense yellow in colour.






Figure 3. Anderson, K. (2021). Damage from White Cabbage Butterfly. [Photograph]. Okotoks, Alberta, Canada.



After around 7 days, the eggs will hatch and from each egg emerges a hungry little caterpillar. These caterpillars quickly get to work munching on leaves, and in their path of destruction they leave behind holes that look like shot-holes, or damage from small hail stones.





Figure 4. Anderson, K. (2021). White Cabbage Butterfly larval (caterpillar) stage. [Photograph]. Okotoks, Alberta, Canada.



Once the caterpillars have gotten big enough, it's time for them to pupate. This is the cocoon (chrysalis) stage of their lifecycle before they emerge as butterflies.




Figure 5. CABI. Pieris rapae Pupa (chrysalis). [Photograph]. Retrieved from: https://www.cabidigitallibrary.org/doi/10.1079/cabicompendium.41167

So, how do you control the White Cabbage Butterfly?

The following methods will help prevent and/ or reduce damage from the White Cabbage Butterfly:


  • Securing a butterfly net (AKA floating row cover) over top of your cabbage crops *the best preventative measure in our opinion - see figure 6*.


  • Interplanting between cabbage crops with plants like sage, rosemary, oregano, mint, catnip, nasturtiums, tomatoes, and celery to deter the pests


Figure 6. Mulvihill, S. (n.d.). Floating Row Cover over Cabbages. [Photograph]. Retrieved from: https://www.spokesman.com/stories/2020/mar/21/in-the-garden-netting-helps-keep-pests-away-from-c/

  • Checking the undersides of the leaves for eggs, caterpillars, and pupa and removing/ squishing them.


  • The application of Bacillus thuringiensis (usually called BTK) dust on the leaves on your cabbage plants. B. thuringiensis is an organic insecticide that will kill caterpillars when they feed on the leaves of your plants. B. thuringiensis is a good option for treating P. rapae because it doesn't harm mammals (like us) or other non-target organisms, like bees! *Always practice caution when applying pesticides and follow the instructions on the label.*






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