Attract three key insects and you’ll find you’ve made some really helpful friends, writes Fiann Ó Nualláin
IF WE garden then we cultivate biodiversity — that’s not just a rich tapestry of plants but a whole world of other life forms. Not just visiting foxes, the neighbours’ cats or alighting birds, not just earthworms and spiders but an amazing array of insects — some come to pollinate, some come to eat your plants, some come to eat the ones that eat your plants — and every gardener will say yes, more of those, please.
Well, it’s easy as they will arrive naturally. An established garden emits fragrances and shines with colours that beacons to these beneficial insects but if your garden is new or you’ve gardened non-organically for a few years in a row then it may be missing out on some really helpful friends. So here are some tips to attract three of the best beneficial insects. It is more than a sustainable practice to invite them in, it is key to a healthy balance. To garden is to be with and of the natural world.
There are several types of lacewing, with the common green (Chrysoperla carnea) being a common garden friend. It was once thought to be a single species, but there are in fact several closely-related species distinguished only by their courtship songs. Active April to October with peaks May to August.
ID: Adults have a pale green body approximately 12mm–20mm and delicate, transparent, lace-like wings with a span up to 40mm. They have long antennae and characteristic golden eyes. Females lay their oval-shaped eggs on a long silken thread of mucus that hardens in the air to distinctively suspend the green egg from slender stalks. Maturing to grey after a few days and soon hatching to grey or brownish larvae that are considered alligator-like with large pincers and well-developed legs.
Benefit: Adult green lacewings pollinate plants but also eat pest insects. Their larvae, often used as a biological control in polytunnel and greenhouse setups, can consume over 200 prey per week — including aphids, thrips, whiteflies, mealybugs, scale insects, spider mites, sundry pest insect eggs and even small caterpillars.
How to attract: Tansy particularly attracts green lacewings but all nectar-rich companions will entice while pollen-bearing plants will help the females with egg maturation. Insect hotels will encourage breeding colonies but young larvae are susceptible to desiccation so a fleece shade, misting and a source of moisture will benefit. A misting of a sugar-water solution mimics the honeydew they both feed from.
Ireland hosts approximately 180 species of hoverfly but the two most frequenting your garden are the common hoverfly (Syrphus ribesii) and the drone fly (Eristalis tenax). Both are around from March to November but peaking now through to September.
ID: Hoverflies employ Batesian mimicry — that’s a way to avoid predation by looking like a more dangerous species. The common is waspish with is yellow and black striped abdomen but without sting, whereas the drone is quite like a male bee (drone) but with a very noticeable dark face stripe and significantly with two not four wings. To distinguish between the sexes of either, look into their eyes — the male’s eyes touch while the female’s are separated by a gap.
Benefit: The adults who hover over flowers that they visit are supreme pollinators while their larvae feed voraciously on aphid-pests.
How to attract: Encourage them into the vegetable bed by planting chamomile and tagetes and other nectar-rich companions. They prefer yellow and also white flowers. The males prefer nectar but the females require pollen for egg maturation so poppies and other wind-pollinated flowers can be added to the borders too. Hoverflies have multiple broods over the year and their egg and larval stage lifecycle is completed in organically rich stagnant water, polluted rivers, slurry and silage and dung. Replicate this habitat with a farmyard manure heap beside your compost heap.
Some years ladybirds are around all summer, others a short sojourn; lifecycle duration varies upon weather patterns (temperature and humidity). They hibernate October to February, but are often not visible in numbers until April.
ID: The ladybird perhaps most familiar is the seven-spot ladybird, the one from childhood books; 5mm–8mm long, red body with black polka dots. Yet there exists 15 different indigenous species with an array of patination and tonal variance; 14-spots, 18-spots, not all red and black either. The 22-spot can be distinctively yellow. There is even a cream-spot ladybird where the dots are off-white rather than black.
Benefit: one of most active predators not just in quantity consumed but in their hunting practice of searching out prey from dawn to dusk. A single ladybird will consume between 50 to 60 aphids per day (5,000 in its lifetime). Both adults and larvae are predators and they also munch scale insects, mealy bugs, leaf hoppers, and various mites.
How to attract: If already in your locality or neighbouring gardens they will eventually find their way to yours. Tansy attracts but the trick is to make them stay; a welcome place to breed or overwinter – insect hotels or log piles and leaf mould. Their diet requires more than aphids so plant pollen-bearers such as fennel, angelica and yarrow. Remember they lay eggs on nettles, so a small weedy corner is a good thing.
If you rely on nature to attract a pest balance in your garden you will notice the difference. You may occasionally still have to squish some greenfly or lay a grease trap but overall your efforts will be less. Once you commit to this natural way it is essential to avoid chemical sprays; not only do they kill beneficial insects upon contact but they poison their food supply. Once you attract the beneficials they will breed in the garden or vicinity. Just by tending the garden you are tending to them and they will help your garden just by doing what they do naturally.