Want to keep the pests away from your fruit without resorting to artificial pesticides? This guide is for you. In no particular order, here are our top ten beneficial predators to welcome into your orchard or garden. Their presence will help improve your fruit yield naturally and reduce the harmful chemicals in your greenspace.
1/. Predatory bugs
Predatory bugs (anthocorids, mirids (capsids) and nabids) are generalist predators that predate upon pests including aphids, codling and tortrix moth eggs and young caterpillars. Flower bugs (anthocorids, pictured) are common in apple and pear orchards.
Emerging in March and April they then congregate on willow catkins before spreading out to other plants. They overwinter as adults.
You can help to boost their numbers by providing artificial bottle refuges in your orchard trees for the adults to over winter in.
Lacewings are beautiful insects of the Order Neuroptera, meaning ‘nerve winged’. There are twelve species of green lacewings found in Britain.
Both the adults and larvae are voracious feeders on aphids; the adults have biting jaws whereas the larvae have piercing and sucking mouthparts. They also eat invertebrate eggs.
Sometimes the larvae camouflage themselves from their prey with debris including the empty skins of their aphid victims with which they cover their body. This helps them to go undetected by any ants that are ‘farming’ the aphids, as does covering themselves with the ‘wool’ from woolly aphids!
Lacewings can be encouraged to breed in your garden by providing a wide range of nectar-rich plants. They also need safe havens to hibernate overwinter, such as log piles and dense hedges.
Plants: Parsley, yarrow, dill, angelica, coriander, cosmos, fennel, dandelion, sweet cicely and cow parsley.
Spiders are under-researched beneficial predators in orchards; whilst investigating fruit trees in unsprayed orchards you can be sure to find many different species present. Spiders feed on a variety of insect available prey including the adults, nymphs and eggs of many species. Not only do they eat other insects but they can also keep pest numbers down by disturb larvae, causing them to fall and die or get eaten by something else. Their webs may also prevent pests from feeding on or egg laying onto the surface of leaves.
4/. Parasitic wasps (Ichneumonidae)
These are non-stinging wasps that lay their eggs on or inside other insects. Once the egg hatches, the larva eats the host alive before emerging as an adult. They are an important predator of caterpillars, sawflies, leaf midge, aphids and ants. As well as carrying out pest control in the late summer and autumn, they have a role to play as a pollinator in the spring and summer.
Plants to attract parasitic wasps: yarrow, dill, mallow, cosmos, lobelia, alyssum, cinquefoil, marigold, coriander, fennel, lemon balm
5/. Ground beetles (carabidae)
These are voracious predators; they love slugs and snails, but in an orchard system they may play an important role in eating sawfly larvae and moth caterpillars and wingless females when on the ground.
Many ground beetles are nocturnal and require shelter and shade shade during the day. A few logs or large stones scattered around your mulch circle will foster a population ready to attack anything emerging from fallen fruit.
Once considered a pest, earwigs are now considered a beneficial predator in orchards. The earwig most commonly found in apple and pear orchards is the common European earwig, Forficula auricularia and is an important generalist predator in the trees, regulating populations of several pests, including aphids, scale insects, and codling moth.
They can easily be attracted into the canopy of your trees by creating a simple bottle refuge, consisting of a 1 or 2l plastic bottle with one end cut off, with a roll of corrugated cardboard stuffed inside, attached upside down (with the cut end downwards – they like it dry!) to the trunk of your fruit tree.
Hoverfly adults are important pollinators being nectar and pollen feeders. Their larvae however are ‘predacious maggots’, and potentially THE MOST IMPORTANT OF THE APHID PREDATORS. They move around on leaves with leech-like movements with their tapered head end hosting two hooks perfect for sucking out the contents of their prey. They are most active feeding at night. Some species are specialist in their aphid preference, while others are generalist. Some hoverfly larvae go down onto the roots to hunt woolly aphid.
Hoverfly adults prefer tiny flowers because they have small mouth parts. Members of the cow parsley family (also known as umbellifers) are perfect for them. These include astrantias, eryngiums, members of the carrot family. The acid-yellow flowers of the biennial Smyrnium perfoliatum, the perennial cow parsley (Chaerophyllum hirsutum ‘Roseum’ and the dainty Anthriscus sylvestris ‘Raven’s Wing’ are perfect. But they are also attracted to orange and bright-yellow flowers.
Plants to attract hover flies: Yarrow, alyssum, dill, cosmos, mallow, poached egg plant, lemon balm, potentilla, marigold, cow parsley, sweet cicely, fennel.
Birds are important predators in orchards. In particular Blue Tits and Great Tits are very handy to have around as they are important predators of several aphid and caterpillar species, particularly when they have nesting chicks to feed. Robins and other common insectivorous birds are also useful. They can play a significant role in keeping these pest numbers down and are a joy to watch and hear, so they should be encouraged into any organic food growing system! Also, their faecal offerings may be small, but all that nitrogen in the soil adds up!
Tits can be encouraged by providing supplemental feed through the winter and well into the summer (squirrel-proof hanging feeders with nuts or fat balls are best) and providing nesting boxes in and around your orchard (ensure that the entry hole is suitable for the species you wish to attract). All birds require water to drink and bathe in – provide a shallow bird bath using something like an upside-down dustbin lid on bricks (with a maximum depth of 5cm for small birds) and keep the water ice-free during the colder months.
Bats are an overlooked beneficial predator. Active nocturnally in the summer months, they play an important role in reducing the population numbers of the problematic moth species, including Codling moth. However, they are not present in all areas so you’ll need to find out about local bat populations from your local Wildlife Trust or bat group. They can be attracted by providing a wide range of plant species in your orchard which, in turn, increases invertebrate diversity and nesting boxes. Bat boxes can also be installed for roosting. Bats tend to be darker coloured boxes that are attached to trees, rather than buildings, with the Schwegler wood-crete style being favoured by ecologists. These must be positioned at least 12-20 feet above the ground and you may have to be patient and wait a few years for them to move in!
Possibly the most well-known of the aphid-munchers, ladybirds and their hungry larvae are one of the most important predators in the orchard. As with all beneficial insects it’s worth getting to know what they look like at their various lifecycle stages as the larvae bears no resemblance to the adults. The tank-like larvae can munch their way through up to 5000 aphids each before pupating into an adult where their hunting resumes.
As with many of the other beneficials, they can be encouraged in your orchard by providing certain plants (the adults also eat pollen and nectar as well as aphids) and habitat, particularly for overwintering adults. Attractor plants include Yarrow, Fennel, Chives, Caraway, Angelica, Marigold, Calendula, Cilantro, Cosmos, Dill, Feverfew, Statice, and Sweet Alyssum.
Nettle patches can also keep ladybirds in your orchard as there is a nettle-feeding aphid species – in the spring these aphids increase their population size which encourages ladybirds to lay their eggs on them. Once these aphids have been eaten they’ll spread out onto your fruit trees hungry for more.
Overwintering bug hotels/refuges like the one described above for earwigs will also house over wintering ladybirds and should be incorporated into your orchard where possible, ideally one on each fruit tree.
All photo credits Russell Miller