What Are Cutworms and What Can We Do About Them?

You’re likely to encounter a number of problems with pests and diseases as you begin your gardening journey. One common pest you may encounter are cutworms. Read on to find out what they are, where you might find them, why they are a problem, and what to do about them.

Gardening is often easier than you might imagine. Even those with the least green fingers can often achieve amazing things. Especially when they have a polytunnel to make gardening easier. But there are always plenty of things that can go wrong.

The best way to arm yourself is by learning more about the pests that can plague you and the things we can do to combat the challenges we face. So read on to learn more about cutworms to become better prepared for at least one of the problems you might face in your garden.

What Are Cutworms?

Cutworms are the caterpillars of a number of different moths. The ones most commonly found in UK gardens are those of the turnip moth (Agrotis segetum), the heart and dart moth (Agrotis exclamationis) and the large yellow underwing (Noctua pronuba). The caterpillars of all these moths look alike. They are a dirty grey colour and grow to around 4cm in length.

The moths lay their eggs over the summer months. The caterpillars can either pupate in autumn, or overwinter and complete their feeding the following spring.

Where are Cutworms a Problem?

Cutworms are most commonly a problem in areas where an area of turf has recently been removed to make a new vegetable garden. (This is because adult moths prefer to lay their eggs in areas where there is a dense cover of vegetation. Cutworms below your lawn or in a neglected area are less likely to be a problem.) Seedlings and young plants placed in a new bed, therefore, are most vulnerable to a cutworm attack.

You may see that the stems of young seedlings have been cut, or discover, upon examining wilted plants, that the roots have been cut off at ground level. Cutworms may well be the culprits. Cutworms can cause damage to mature plants too. They can chew on stems and lower foliage and leave behind holes and weakened plants. In summer, you may also discover that cutworms have fed on the roots of lettuces, on potato tubers, and on root vegetable crops.

If you lift a wilted plant, if a cutworm is to blame, you will often find it beneath the affected plant and can remove it and dispose of it away from your growing area.

Are Cutworms Always a Problem?

It is important to remember that while cutworms can be a problem, especially in a newly established kitchen garden, they can also be a beneficial part of the garden ecosystem. Cutworms are an important food source for a range of garden wildlife. They are eaten by predatory beetles, birds, and garden mammals such as hedgehogs, for example.

It is also important to remember that the adult moths also have a number of ecological purposes. In an organic garden, even pests have their places. Moths may often annoy us. But they are also pollinators, and indicator species that help us learn about changes to an ecosystem, and how healthy it is.

Dealing With Cutworms

Create a Biodiverse and Balanced Ecosystem

The most important and best way to stay on top of a cutworm problem is by making sure your garden is a rich and thriving ecosystem, with a range of beneficial plant and wildlife interactions. By making your garden as biodiverse as possible, you can create an outside space that allows harmony to reign.

As mentioned above, cutworms are a food source for a range of garden creatures. So to keep cutworm numbers down, it is important to do whatever you can to attract predators to your garden. And to keep them around.

For example:

• Create habitat and ‘bug hotels’ for predatory beetles.

• Attract birds with bird-friendly planting schemes. Give them plenty to eat, and places to shelter and to nest, within and around the plants that you grow.

• Create garden ponds, or bird baths so birds (and other wildlife) have access to fresh water to drink and to bathe in.

• Create brush piles, garden linking tunnels and hedgehog hotels to attract these beneficial mammals to your garden.

Check For Cutworms in New Growing Areas Before Planting Out

In a ‘no dig’ garden, we generally try to disturb the soil as little as possible. But a little foraging around in a new growing area prior to planting could reveal these pests. You may be able to discover and unearth cutworms before they get the chance to do any damage. Simply remove these pests from the soil as they are found.

Consider Removing Dead Plant Material Over Winter – Don’t Mulch Until Spring

Another thing to think about is that cutworms overwinter in dead plant material. In a ‘no dig’ garden, we tend to sheet mulch growing areas throughout the year. But if cutworms are an issue where you live, it might be a good idea to avoid laying plant mulches over winter. Instead, use green manure cover crops and chop and drop these in spring.

Water Your Growing Areas Well

Cutworms are very vulnerable to watering and irrigation when young. So to avoid problems with cutworms, sometimes all you have to do is water well. Well watered plots are often free from cutworm problems. So this is another reason to make sure that you are getting it right when it comes to watering in your polytunnel or elsewhere in your garden.

Create Physical Barriers

To stop cutworms from destroying your seedlings, you can place a cardboard collar around the plant stem to create a barrier between the stem and the soil. Cutworms will usually not climb over such a collar to reach the stems. Aluminium collars, or plastic containers with the tops and bottoms removed can also be used.

Growing plants below fleece, mesh or another protective covering are also less likely to be attacked. So even when you are growing inside a polytunnel, it can often make sense to employ a second layer of protection for vulnerable plants.

These are just a few tips to help you tackle and deal with one common pest that you might find in your garden. Remember, the goal is not to eliminate them entirely from the ecosystem. The goal is simply to prevent them from becoming a problem in your food production and gardening efforts.

When we take small, simple steps to improve our garden ecosystems, we often find that nature has its own forms of pest control. And when you have a balanced ecosystem, all losses are small and manageable. And we find we can often ‘live and let live’ when it comes to the creatures with whom we share our gardens.

Have you had a problem with cutworms in your polytunnel, or elsewhere in your garden? Share your experiences, tips and suggestions in the comments below.