This year I noticed a large amount of small, white delicate butterflies in my garden and yard areas. These little visitors are actually an Imported Cabbage Worm Butterfly (Pieris rapae (Linnaeus) and while they are attractive they can bring some damage to your garden brassicas.
Plants in the brassica family include cabbage, broccoli, kale, collards and turnips. Many people enjoy growing and eating these healthy vegetables so if you notice these insects, what do you do to avoid crop loss and protect your plants?
One way is to use floating row covers while these butterflies are active. This lightweight fabric type protection will allow the air and sun, but is a barrier against the butterflies landing on your plants and laying their eggs. Another includes the use of the natural bacteria Bacillus thuringiensis Kurstaki strain. See the CSU Extension fact sheet on http://www.ext.colostate.edu/pubs/insect/05556.html for advantages and disadvantages of using this natural control. In addition, check all of your plants often for the caterpillars and the eggs for these insects. You can remove and discard the eggs and caterpillars and avoid using pesticides.
|Cabbage Moth Caterpillar|
|Cabbage Moth Eggs|
Sites such as this one show pictures that will help you in your identification:
If you choose to use treatment to eliminate these insects, this publication from CSU can also advise you on other options or you can call your County Extension Office for more assistance.