My cabbage plants have little green balls inside. Is this normal or should I...

Asked June 25, 2020, 2:12 PM EDT

My cabbage plants have little green balls inside. Is this normal or should I be concerned?

Summit County Ohio

2 Responses

Hi. Thanks for sending a photo. Those little dark green balls are frass, which is the technical name for insect feces. The producer of that frass is in your photo, though it is difficult to see thanks to its color camouflage. I have circled it on the attached version of your photo. It is the larva (caterpillar) of a moth, and there are several types that commonly feed on cabbage and related garden vegetables. The U. of Minnesota has a very good article here on the identification and control of these caterpillars. One good option is to hand pick them and toss them into soapy water. They are small and difficult to see, but as you “train” your eye, you will get better at spotting them. Also, the frass is a conspicuous clue to their location. Facilitating natural enemies can help (tips are provided on that U. of Minnesota page), and on small caterpillars, you can use a non-toxic pesticide containing the bacterium Bt (short for Bacillus thuringiensis). The Minnesota Dept. of Health has a short explanation of Bt here. However, any pesticide labeled for use against caterpillars on cabbage will work. With Bt or any other pesticide, be sure to read and carefully follow the label directions.

It all seems so simple and logical once you know what you are looking at. Thank you so much for enriching my knowledge as I venture in to growing different plants this year.