March 13th, 2023 by Sarah Miles

Critters in your lawn may not be your idea of fun but good gardening is all about eradicating the harmful ones while keeping the ‘good guys’. That’s because there is some creepy crawlies that will actually help your horticultural endeavours rather than hinder them.

Pests and biodiversity

So, the two types of creatures we’re talking about are pests, such as leatherjackets, chafer grubs, lice, and green flies that will destroy your beloved lawn and other plants, and the ones that enhance the ecosystem of your garden, such as earthworms, bees, and spiders. It’s all about controlling the former and encouraging the latter and these two ideas work in harmony, as we’ll come on to shortly.

What pests do to your lawn

The most common lawn pests are chafer grubs and leatherjackets. Chafer grubs are the larvae of chafer beetles while leatherjackets are the larvae of crane flies (daddy long legs). Both live in the soil and feed on the roots of grass, thereby eventually killing it at the root level meaning it won’t grow back. The most obvious sign that you have a problem is yellowing patches of grass that easily pull out of the ground because the roots are so weakened.

Preventing an infestation

These pests can be quite difficult to eradicate once they infest your soil, so the best form of defence is prevention and it’s not that difficult to do; it’s really all about good lawn maintenance. Strong, healthy grass is much less vulnerable to pests because it’s more robust and resistant to such invasions. Caring for the grass and improving soil quality are the keys to healthy lawns and pest prevention. Here’s what you should be including in your routines:

Mow regularly to the right length

Mowing may seem like a bind over the spring and summer when growth is at its peak but frequent cutting to maintain grass at optimum length is excellent for encouraging grass to grow faster and thicker, giving better coverage and creating less opportunity for pests and weeds to take hold. Don’t cut it too short, as this can weaken the grass. Aim for a length of around 2.5-4cm.

Scarify and aerate

These are jobs that just need doing once or twice a year (usually in spring and autumn) and will deliver great benefits to your lawn. Scarifying is the process of removing excess organic matter from the roots, allowing air, sunlight, and rain to penetrate the roots and soil. Aeration is about improving drainage in the soil by spiking holes into it. Leatherjackets in particular like wet soil so allowing the lawn to retain too much water will make it an attractive environment for crane flies to lay their eggs.

Boost soil quality

Soil quality is an essential part of the mix for growing healthy plants. You can improve soil quality in a number of ways, including adding organic mulch and compost or boosting nutrient levels by treating it with iron sulphate. As well as enabling the grass to grow stronger, this will make the soil slightly more acidic which is, among other things, less hospitable to pests.

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Keep on top of weeds

Removing weeds not only improves the appearance of your lawns but there are functional benefits as well. Weeds can aggressively compete for soil nutrients, stealing it from the grassroots, plus they tend to harbour the pests you’re trying to control. Keep pulling them out as they appear and make sure you get the root as well, otherwise, it will come right back (the phrase ‘grows likes weeds’ was coined for a reason!). A weed puller can help with this.

Fighting ‘bad’ critters with ‘good’ critters

Nature really is a marvellous thing, and a well-balanced ecosystem often takes care of things itself. Like most living creatures, the kinds of pests you find in lawns and on plants have their own natural predators so encouraging more of these in the garden is a huge weapon in your armoury.

Spiders, ladybirds, and even wasps feed on grubs and larvae so attract them by planting things like oregano, sunflowers, dill, and daisies. Birds will also control numbers so add bright flowers, bird baths, and feeders to bring them into the garden (this can be a joyful experience in itself). And if you want to control things like aphids and green flies, and you have the space, consider a pond to encourage frogs and newts.

If you are concerned you already have a pest infestation, you can consider introducing nematodes, which are bacterial worms that kill specific pests. You do need to know which pest you have though and buy the nematodes accordingly.

Earthworms are also amazing creatures. They won’t kill pests but they will do plenty to improve soil quality and drainage, which we have already established helps significantly. They naturally help to aerate and loosen the soil by creating tunnels as they move through it and will break down and process decaying organic matter. Even their waste is beneficial; it’s like natural compost! Worms will be attracted by good-quality soil so doing all of the above should lead to bigger worm populations.