Zebra caterpillars: colorful and clustered on Minnesota farms

 Marissa Schuh, IPM Extension Educator, mschuh@umn.edu

Growers are reporting large, colorful caterpillars hanging out in groups on assorted crops.  They are most often being seen brassica crops, though they have been spotted feeding on strawberries and tomatoes.

Large and colorful, zebra caterpillars are easy to spot. Photo: Marissa Schuh, UMN Extension.

The large, colorful caterpillars are zebra caterpillars.  These pests seen only occasionally on vegetable crops, most often in brassicas. They have distinctive yellow stripes running down their body, and if you look closely, you will see the repeating black and white strips that give them their name.

Young caterpillars are often found in a clustered area of the field, as the moths lay their eggs in a group and the caterpillars don't mind all feeding together once they hatch. As the caterpillars grow, they spread out a little bit and feed singly.

The damage they cause is typically pretty minor.  They may attack a few plants heavily, but often aren’t distributed throughout the field (the way more common brassica caterpillars are).

This caterpillar hatches from eggs masses and are often found clustered in the field. Photo: Whitney Cranshaw, Colorado State University, Bugwood.org

As for dealing with them? They can be dealt with the same way you deal with other caterpillars, be it via physical removal or spray.  The smaller the caterpillars are, the more effective spray products will be.  See the Midwest Vegetable Production Guide for spray options, they will be lumped in under the "caterpillar" category.

Just because you are seeing them this year doesn’t mean they will become a chronic problem on your farm.  They seem to appear sporadically on different farms every year.