At a glance
Lacewings are among the most effective natural pest controllers available to any UK gardener, yet they are far less well known than bees or butterflies and rarely deliberated catered for. The larvae of common green lacewings are voracious predators that feed almost exclusively on soft-bodied insects – aphids, thrips, whitefly, spider mites and the eggs and young larvae of a wide range of garden pests. A single lacewing larva can consume several hundred aphids before it pupates. Unlike sprays or physical controls, lacewing larvae work continuously throughout the day and night, seeking out prey actively rather than waiting for contact.
Adults are nectar and pollen feeders, requiring flower sources to sustain themselves through the season. This means that a garden can support lacewings at both life stages with the right combination of flowering plants for adults and undisturbed sheltered spots for eggs, larvae and overwintering pupae. The investment required is modest – a patch of umbellifers, some hollow-stemmed or rough-barked overwintering shelter, and a reduction in the kind of intensive autumn tidying that removes the sites lacewings depend on for winter survival.
Why lacewings matter in the garden
The pest control value of lacewing larvae is disproportionate to the size and visibility of the insects themselves. Adult lacewings are delicate, slow-moving and largely nocturnal – easy to overlook and easy to dismiss as incidental visitors. But each adult female lays hundreds of eggs over her lifespan, placing them individually on stalks above aphid colonies so the hatching larvae drop directly into their food source. When lacewing populations are established in a garden, aphid pressure on roses, beans, brassicas and soft fruit is visibly and consistently lower than in gardens without them – not because lacewings eliminate every aphid but because they are present throughout the season, consuming infestations before they build to damaging levels.
Lacewings are also valuable as part of a broader beneficial insect community. Where lacewings are present in numbers, other predatory insects tend to follow – the aphid populations that lacewing larvae depend on also attract parasitic wasps, ground beetles and hoverfly larvae, all of which contribute to the same natural pest management system. Building a garden that supports lacewings is not a narrow intervention but a contribution to a self-reinforcing ecological community that becomes more effective over time as populations establish and diversify.
Lifecycle and identification
There are over 18 species of lacewing native to the UK, but the one most commonly seen in gardens is the common green lacewing, Chrysoperla carnea. Adults are immediately recognisable – delicate pale green insects with large, intricate, heavily-veined wings held tent-like over the body at rest. The wings have a golden iridescence in certain light and the eyes are conspicuous copper-gold. Adults are around 12-15mm long and are often the species found sheltering indoors in autumn and winter as they seek overwintering sites in leaf litter, tree bark and hollow stems.
The larva is the life stage responsible for pest control and the one that benefits most directly from garden management decisions. Larvae are active hunters that patrol plant stems and leaves, using their large sickle-shaped jaws to seize prey. They go through three larval instars over approximately two to three weeks before spinning a pupal cocoon. In warm seasons with high aphid pressure, a garden can support two to three complete generations of lacewings between April and October – meaning populations can increase substantially within a single season if conditions are right.
Lacewings found indoors in autumn are not pests – they are overwintering. Common green lacewings frequently enter houses and sheds in late September and October, seeking sheltered sites for winter. They do not feed, breed or cause damage indoors. If one is found indoors in winter, leave it or move it gently to an unheated shed, garage or outbuilding where it can complete its dormancy undisturbed. They will leave naturally when temperatures rise in spring.
Plants that attract lacewings
Adult lacewings feed on nectar, pollen and the honeydew excreted by aphids and other plant-sucking insects. They are drawn to flowers with open, accessible structures – umbellifers, composites and other shallow-nectaried species. The combination of open flowers for adult feeding and the presence of aphid colonies as both adult food (via honeydew) and larval prey makes certain plant combinations particularly effective at establishing lacewing populations. A border that includes fennel, dill, angelica and marigolds alongside plants that naturally attract aphids – such as nettles and nasturtiums – provides everything a lacewing needs at both life stages within a small area.
Positioning matters as much as plant selection. A flowering strip or patch placed immediately adjacent to a vulnerable crop – a row of beans, a rose bed, a brassica bed – brings adult lacewings into close proximity with exactly the aphid colonies they are looking for when choosing egg-laying sites. Lacewing females are cued to lay near honeydew sources, and a patch of phacelia or dill between the aphid colony and the rest of the garden creates a concentration effect that establishes larvae where they are most useful. This is the principle behind companion planting strips in vegetable gardens, and it works with lacewings just as it does with hoverflies and parasitic wasps.
Overwintering habitat and lacewing houses
Overwintering survival is the critical bottleneck for lacewing populations in UK gardens. Adults of the common green lacewing spend winter in a state of diapause – a form of dormancy triggered by shortening day length in late summer. They seek out dry, sheltered spots that remain frost-free: the hollow stems of dead umbellifers, the rough bark of trees, dense ivy, gaps in stone walls, unheated sheds and log piles. Gardens that remove all dead plant material in autumn, clear ivy from walls and eliminate log piles actively reduce the overwintering capacity that determines how large the next season’s lacewing population can be.
Dedicated lacewing houses – commercially available wooden boxes filled with corrugated card, straw rolls or hollow bamboo tubes – provide a targeted overwintering resource and are effective when positioned correctly. Height matters: lacewing houses should be placed at 1-2 metres above ground, sheltered from prevailing rain and facing south or east to benefit from morning warmth in spring. A house facing full north rarely attracts occupants. The corrugated card or straw filling should be replaced each spring after adults have departed, as old material accumulates moisture and can harbour pathogens. A lacewing house is a supplement to natural habitat, not a substitute for it – gardens with hollow stems and dense ivy will always support larger lacewing populations than those relying on artificial structures alone.
Garden management for lacewings
The garden management decisions that most benefit lacewings are almost identical to those that benefit hoverflies, ground beetles and other beneficial insects – which is unsurprising given that these species share the same habitat requirements at similar life stages. The overarching principle is that a degree of structural complexity and seasonal untidiness creates the layered habitat that all these species need, while an aggressively manicured garden – however attractive it may look to human eyes – is effectively a biological desert for invertebrates that overwinter in plant stems, leaf litter and bark.
Lacewing populations respond to garden improvements within a single season. A garden that introduces a patch of umbellifers, delays its autumn cutback and provides a lacewing house or some ivy-clad wall space will see adult lacewings visiting within weeks of the flowers opening. Larvae will be present on nearby plants wherever aphid colonies exist. By the second season, with overwintering success improved, populations are typically noticeably higher and the pest control benefit measurably greater. The return on a small investment of habitat and management restraint is rapid and self-sustaining.
Lacewing eggs are easy to destroy accidentally. The distinctive stalked eggs are placed individually on fine silken threads attached to plant stems, usually among or near aphid colonies. They are small – about 1mm long – and pale green or white. When hand-removing aphids by pinching or washing, check the stem carefully first. Removing aphids from a stem that carries lacewing eggs removes the very predators that would otherwise control the colony within a week. If eggs are present, leave the colony and check again in five to seven days for hatching larvae.
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