Natural pest control focuses on reducing or completely eliminating the use of chemical pesticides in favour of safer, more sustainable methods. These methods can include organic repellents, physical barriers or attracting more beneficial insects to your garden.
By using natural pest control methods and avoiding synthetic solutions, gardeners can nurture the health and vitality of their garden in the long run. A biodiverse garden that contains a variety of life tends to balance itself out, keeping potentially troublesome populations of any one species in check.
Synthetic pesticides are tempting both for commercial and home growers, largely because they are a very fast and effective solution. The problem is they are too effective. Generally these kinds of products do not discriminate between ‘good’ and ‘bad’ pests, and have been widely linked to the decline of pollinator populations.
Chemical pesticides can leave residues behind on your plants, and you only have to glance at the product labels to see that they can also be potentially harmful to pets or children. What’s more, residues can run off into rivers or streams, contaminating waterways and harming aquatic life.
Generally speaking, natural pest control methods are less of a quick fix. They can often require repeat applications or complementary methods, in contrast to the ‘nuclear option’ of chemical pesticides. The trade-off is that they are less destructive towards the garden ecosystem and they leave very little or no residues behind.
Biological control such as nematodes are often used in commercial or agricultural settings. These are living microscopic organisms that target a particular part of an insect’s lifecycle (most commonly larvae). When carefully timed and applied, these can be a very effective control method with minimal collateral damage.
Other forms of organic pest control prioritise prevention over cure. This can involve strategic planting, ‘trap crop’ planting, encouraging beneficial insects who feed on problem insects etc. Physical crop barriers like mesh netting, cloches or row tunnels can prevent insects from reaching your plants or seedlings, considerably reducing the chances of an infestation.
It’s worth remembering that Natural vs Synthetic pest control is not always a 100% black and white scenario. Some spray solutions that are certified organic can still be harmful in their own way. Obviously they are going to harm the insects or larvae that they are targeted towards, but they can also include warnings about not contaminating water due to their effects on aquatic life, for example.
Ideally, one of the key principles of natural and humane pest control is to stop thinking of them as ‘pests’! They are just sharing the garden space with us - and as annoying as they might be, every insect or living organism plays its role in a healthy ecosystem.
Beneficial insects are welcomed in gardens or agricultural settings for a number of reasons:
Hoverflies resemble wasps, but they don’t sting. They play a vital role in the garden, both in terms of pollination and balancing out other insect populations. While the adult hoverfly primarily feeds on pollen or nectar, their larvae feed voraciously on aphids, leafhoppers, and other pests. When hoverfly larvae are present in sufficient numbers, they can reduce aphid populations by 70-90% - and possibly even higher.
Ladybirds The seven-spot ladybird, commonly seen in Irish gardens, is known to feed voraciously on aphids. The average lifespan of a ladybird is typically one year - but in that span of time they can eat as many as 5,000 aphids. Their larvae meanwhile can polish off a few hundred more. Planting native hedgerow or leaving piles of dead leaves can encourage a healthy ladybird population.
Lacewings Lacewings are delicate, almost transparent-looking insects with large wings and golden/green eyes. Their larvae are tellingly referred to as “aphid lions”, and are equipped with sickle-shaped mandibles for piercing and sucking out the fluids of soft-bodied insects. Plants to attract lacewings include cosmos, fennel, dill and yarrow.
Ground Beetles These silent but effective nocturnal predators are partial to a wide range of invertebrates (including slugs, caterpillars and vine weevil larvae). As a bonus, some species can also keep weed seeds from establishing. Log piles, leaf litter or compost heaps can provide suitable habitat. It’s also good to avoid excessive disturbance or tilling of the soil where they dwell.
Parasitic Wasps Despite their somewhat negative moniker, parasitic wasps are non-aggressive and typically don’t sting. Instead their ‘stingers’ are used for laying eggs on or inside host pests such as caterpillars, aphids or cutworms. The larvae consume the host from within, effectively suppressing populations. Species include braconid or ichneumonid wasps. You can plant dill, alyssum, or cosmos flowers to attract these beneficial wasps.
Making your own DIY pest spray for the garden is a great natural way to protect your plants without using harsh chemicals. You will be safe in the knowledge of what the ingredients and additives are.
DIY plant or pest sprays are usually a mix of materials such as:
A strong spray of soapy water (or even plain water) can be surprisingly effective in managing aphid; however it may need to be repeated daily until the plant is no longer under threat.
Garlic solution sprays are often used by gardeners to discourage troublesome pests. and there are commercial products available that use garlic as the key ingredient. Garlic is effective as a deterrent because it contains natural compounds like allicin and sulfur, which produce a strong odor and taste that many insects and animals find unpleasant.
Caution should still be taken with homemade sprays. Neem oil for example is commonly used in some parts of the world, but its use as a natural pesticide is banned in the UK due to its potential toxicity.
Ecofective’s Bug Control spray immobilizes bugs by encapsulating them and preventing them from feeding. It should be reapplied every 5-7 days as new eggs hatch. This spray is labelled as being child and pet safe, but it can help control greenfly, blackfly, spider mites, scale insects and other troublesome garden visitors.
The Ecofective range also includes a Slug Defense spray and a spray for houseplants, both of which also contain nutrients to promote plant growth. Agralan’s Whitefly Killer, meanwhile, is based on seaweed extract and acts on the insect through a physical mode of action.
Some other alternatives to synthetic pesticides include Slug Beer Traps (slugs are drawn to the scent of fermenting yeast), hanging taps that use floral lures to attract specific insects (e.g. chafer beetles or raspberry beetles) or rough granules that can form a physical barrier around plants.