What the Heck is Cabbage Worms?

What are Cabbage Worms?

Imported Cabbage worms are the same pest as "cabbage worms.” You usually see butterflies which is sometimes called by the easy name of small whites and cabbage whites.

One of the most favorite meals for cabbage worms would be your cauliflower, broccoli, kale and other members of the cabbage family.
You might see a hole in the leaf here and there. Don't get concerned about it. The vegetables can withstand a few destructions when it is older. The seedlings and beginning stages of the leafy delight gets most of the damage.

Identification

How to Identify Cabbage Worms

The worms are usually green in the larva stage. If you look closely, you may see yellow stripes. Now there is a cabbage looper which have been green and yellow caterpillars.  The difference between the cabbage worm and the looper is this: The Looper has no middle legs and have distinct walk that allows them to raise and lower their bodies upon movement.  Cabbage worm become white cute butterflies with black markings. Let's not get it twisted but this pretty butterfly will lay eggs on the outside of your leaves.  Thus, eating the leaves of your bounty.
Where you find cabbage worms and cabbage loopers, you also might find the eggs and larvae of the diamondback moth and the zebra caterpillar. The camouflage of these creatures is excellent, so you will often see the frass, or fecal matter, that they leave behind before you see them.

Cabbage Worm Damage

One of the traits of a cabbage worm is the way it destroys cabbage, cauliflower, or the heads of broccoli. Eat can eat it without you even noticing it. When the damage is done you may find the remnants of leaves that look like veins with the foliage gone. 
If you do not detect the worms your whole crop can be destroyed in a matter of months.




Photo Credit: Purdue University. Imported cabbage worms feed on the flesh of foliage and often hide on the undersides of leaves.

Control and Prevention

How to Get Rid of Cabbage Worms

• Pick the worms by hand. This will take all day.
• Sticky traps that are yellow is a great way to catch the larvae... but may also catch beneficial insects.
• Treat with BTK every 1 to 2 weeks will slow the progress of the cabbage worms.  Sevin also is effective. Use detergent to make a surfactant solution.
• Cornmeal sprinkled over the leaves of cabbage will cause the larvae to swell and die. This is a folk tale. It doesn't hurt to try it.
• Seek advice from  Cooperative Extension for your area’s regulations on chemical control.
• Interesting advice from The 1963 Old Farmer’s Almanac states: People sprinkled rye flour over cabbage plants in the early morning. The flour dehydrated the cabbage worms. I don't know if it works but what the heck!

Photo Credit: York College of Pennsylvania. It is hard to control cabbage worm damage, so it’s best to prevent them from coming to your garden in the first place.

Prevent Cabbage Worms

• User row covers to stop the butterflies from laying eggs on your plant. Butterflies will not nest
• Cabbage worm does not like thyme. We call this a companion plant.  Place the thyme near the cabbage family Cabbage worms are attracted to mustard plants, so planting mustard near more valuable plants can be a good trap for cabbage worms. Once they take over the mustard, you can destroy the plant.
• Cabbage worms like to camouflage. So it might be a good idea to plant different color cabbages. The idea is the cabbage is a different color such as red, the cabbage worms will not nest.

Plants Affected

• Cabbage
• Kale
• Cauliflower
• Broccoli