How to protect the garden from the ravages of cutworms (Cutworms)

Cutworms can destroy a vegetable garden overnight!

Indeed, this scene is unfortunately all too common: You have just finished planting your garden and transplanted your little plants that you have been pampering indoors for weeks, you are going to sleep but when you go to the garden the next morning what a horror, several plants are cut at the base! The culprit, the famous cutworm. In this blog post, we show you who it is, how to recognize it, how to prevent it and how to get rid of it.

What are cutworms?

Cutworms are actually the larvae of several species of moths. Butterflies will lay their eggs on plant debris from spring to fall. The larvae can therefore hatch at any time during this period, but usually the fall ones will overwinter to be "ready to attack" early in the spring when the seeds and small plants are vulnerable. It is therefore at the beginning of the gardening season that they cause the greatest damage to the garden.

How to recognize them?

Cutworms are sneaky and usually hide during the day. To find them, you have to go to the garden at dusk, on a cloudy day or with a flashlight in the evening when it is dark and look at the base of your young plants or transplants.

Different species can have different colors. Obviously they can be gray, but also pink, green or black and be as long as 5cm (2 in). When they are not moving, they are generally rolled up on themselves.

When they become adults, the cutworms evolve into moths with brown or dark gray wings (see photo). They are about 4cm long and their wings also spread out to about 4cm. Recognizing the adults will keep you alert as the female will likely lay her eggs in the dry soil of your garden.

How to recognize their presence?

In the spring, they gnaw the stems of small plants at the base or even below ground level. They also feed on the roots and leaves of these plants. Usually, even if only the bottom of the plant is affected, the entire plant will wilt and die. They cause a lot of damage in gardens, and very quickly.

It is possible that during the summer they climb to the top of the plant to feed on the young leaves.

How to prevent their ravage?

In order to avoid the worst, we suggest you try these few tips:

  • Protect each plant stem by wrapping a cardboard or aluminum foil collar at least 4" high around it.
  • If you see a cut stalk near the ground, poke your finger around it 1-2 inches deep and you'll likely find the culprit.
  • Go hunting for cutworms. A few times a week, go visit his garden with a flashlight, gloves and a bucket filled with soapy water when it gets dark. Pick up the cutworms and put them in soapy water.
  • Sprinkle diatomaceous earth around the stems of the plants to be protected. This natural powder will dehydrate the worms. Be careful, it acts in the same way with beneficial insects in the garden such as bees or butterflies, so it is very important not to use it near flowers.
  • Apply a biological insecticide at the end of the afternoon of the BTK type which is in fact a bacterium which attacks soft-bodied insects and their larvae.

How to get rid of it in the long term?

  • Avoiding planting our young plants and transplants outdoors too soon will cut off the food source of the cutworms that are just waiting for this abundance to feed and avoid much of the damage they can cause.
  • To keep laying mothers away, avoid keeping long grasses around your garden. Continue to mow around your garden in the fall to expose dormant eggs or larvae hidden in these plants or on the soil surface.
  • Birds are a natural predator of cutworms. Consider creating an inviting environment for them to come and enjoy them.

Good luck and good harvests!

Photo credits: and John Obermeyer, Purdue University.