The Green Lacewing Explained

A green lacewing is a delicate, pale-green insect of the family Chrysopidae, named for its transparent, finely veined wings, and its larvae are voracious predators of aphids and other soft-bodied pests, which makes the lacewing one of the most useful insects on Indian farms and in gardens. The adult is a fragile flier with golden eyes, while the young, known as “aphid lions”, are the hungry stage that does the pest control.

Green lacewings are found across India on crops, shrubs, trees and kitchen-garden plants, and they turn up at night around lamps and window lights. Indian agricultural research bodies have studied and mass-reared lacewings as a living alternative to chemical pesticides, so the insect is of interest to farmers as well as to naturalists.

Key Takeaways

• The green lacewing belongs to the family Chrysopidae in the insect order Neuroptera, which also contains antlions and owlflies.
• A green lacewing larva, called an aphid lion, can eat very large numbers of aphids, whiteflies, mealybugs and other soft-bodied pests during its development.
• Green lacewing eggs are laid singly on thin silk stalks, a feature that protects the newly hatched larvae from their hungry siblings.
• Adult green lacewings feed mostly on nectar, pollen and honeydew rather than hunting, and they are mainly active after dark.
• Green lacewings are mass-reared in laboratories and released as a biological control agent against crop pests, including in India.
• Many green lacewings can detect the ultrasonic calls of bats and dive away from them in flight.

What Is a Green Lacewing?

A green lacewing is a small, soft-bodied, net-winged insect, typically pale green, with long antennae, bright golden or copper-coloured eyes and two pairs of large, clear wings crossed by a green network of veins. It belongs to the family Chrysopidae, whose name is derived from Greek words meaning “golden” and “eye”.

The family contains several thousand species worldwide, and many occur in India. Species of the genus Chrysoperla are among the most widespread and best studied, and one group of closely related species, the Chrysoperla carnea complex, is used in biocontrol around the world. A species named Chrysoperla zastrowi sillemi is common on Indian crops.

Why is it called a lacewing?

The lacewing gets its name from the wings, which are covered in a fine lattice of veins and cross-veins that looks like lace. The wings are held in a tent-like roof over the body when the insect is resting, and they give the lacewing a ghostly, fragile look that contrasts sharply with the larva’s fierce behaviour.

What Does a Green Lacewing Look Like?

A green lacewing looks like a slim green insect with an elongated body, thread-like antennae and big transparent wings that are longer than the body. The insect is typically about one to two centimetres in body length, and its eyes shine metallic gold or coppery in light, a feature that makes it easy to recognise at close quarters.

The delicate green colour of many species fades to a dull yellow-brown during winter or in resting adults. Wings are usually lightly iridescent, and their stiff, evenly spaced veins are visible even from a distance when the insect is held against light.

• Body: slender and pale green, often with a pale stripe along the back
• Eyes: large, golden or coppery and widely spaced
• Antennae: long, thin and thread-like
• Wings: four, transparent, net-veined and held roof-wise at rest
• Flight: slow, fluttering and mostly at dusk or night

Where Are Green Lacewings Found in India?

Green lacewings are found in nearly every part of India where there are plants and sap-sucking insects, from vegetable plots and cotton fields to orchards, sugarcane and garden hedges. They are not restricted to wild country and often thrive in cultivated land provided pesticide use is moderate and flowering plants are available for adults.

Adults rest on the undersides of leaves by day and fly at night, which is why lacewings are often noticed first around verandah lights and window screens, particularly after the monsoon when insect numbers rise. Lacewings favour crops with high aphid populations, such as cotton, brinjal, okra, mustard, pulses and various vegetables, as well as fruit trees.

How Does the Green Lacewing Life Cycle Work?

The green lacewing life cycle has four stages: egg, larva, pupa and adult, with three larval stages called instars. The whole cycle can be completed within about a month or so in warm conditions, though timing depends heavily on temperature and food, and several generations can occur in a year.

The adult female may lay several hundred eggs over her life, depending on species, diet and conditions. The pupal stage lasts roughly a week or two in warm weather, and the entire life cycle of the lacewing is shaped by the availability of prey and the weather.

Why Do Lacewing Eggs Sit on Stalks?

Lacewing eggs sit on long, slender silk stalks to protect them from predators and from newly hatched siblings. The female lays a droplet of sticky secretion on a leaf, draws it into a fine thread and places the egg at the top, producing a tiny stalked egg that looks like a fungus or a grass seed on the leaf.

This is a very practical adaptation. Lacewing larvae are cannibalistic and will eat unhatched eggs and each other if they get the chance. The stalk lifts the egg away from the leaf surface, away from crawling ants and other egg-eating insects, and gives the newly hatched larva a moment to climb down onto the plant before it meets a neighbour. The eggs are often seen in neat patches on the undersides of leaves of crops that carry aphids.

What Do Green Lacewing Larvae Eat?

Green lacewing larvae eat aphids and many other small, soft-bodied pests, including whiteflies, mealybugs, leafhoppers, thrips, spider mites, scale insects and the eggs and tiny caterpillars of moths. For this reason the larva is nicknamed the “aphid lion”, because it hunts small prey in the way that a lion hunts large animals.

The larva seizes a victim with its pair of hollow, curved jaws, injects a digestive fluid and sucks out the body contents, leaving the empty skin behind. A single larva may consume hundreds of aphids over the course of its development, and the number rises with each stage; the third instar eats the most. Its appetite and the ability to search leaf surfaces vigorously are what make the lacewing so valuable in the field.

Why do some larvae carry a pile of rubbish?

Some lacewing larvae carry a packet of debris on their backs, built from the empty skins of their victims, bits of plant material and wax. This “trash packet” works as camouflage and as a physical shield against ants and other predators that would otherwise attack the larva. Species that do this are sometimes called trash-carrying or debris-carrying lacewings, while other species have a bare body.

What Do Adult Lacewings Eat?

Adult green lacewings in most species eat nectar, pollen and honeydew, the sugary liquid excreted by aphids and scale insects, rather than hunting prey. Some species also feed on small insects, but many are essentially nectar and pollen feeders, which means the adult is valuable mostly as the egg-laying stage and as a pollen-visiting insect.

For this reason farmers who want lacewings on their land benefit from planting flowering plants around fields, such as coriander, marigold, sunflower and other species with small, open flowers. A field with flowers and a moderate pest population can keep adult lacewings nearby, laying eggs close to the prey the larvae will need. Fields that are bare, sprayed heavily or entirely sterile of nectar tend to support few lacewings.

How Is the Green Lacewing Used in Biological Control?

The green lacewing is used in biological control by rearing eggs or larvae in laboratories and releasing them in crops to suppress aphids, whiteflies, mealybugs and similar pests. Biological control is the use of natural enemies to keep pest numbers down, and lacewings are suited to it because the larvae are hardy, hungry and easy to rear on substitute prey such as the eggs of the rice moth.

In India, research institutions under the Indian Council of Agricultural Research (ICAR), including the National Bureau of Agricultural Insect Resources (NBAIR) in Bengaluru, have worked on lacewing rearing and release in crops such as cotton, vegetables, sugarcane and fruit trees. Laboratory-reared eggs, often shipped on cards or as larvae in separate cells, can be placed in the field when the pest population begins to grow.

Because larvae eat one another, mass-rearing requires keeping them apart in individual cells or giving them plenty of food, and releases are normally made as eggs or young larvae. Lacewings do not eliminate pests alone, but they are a component of integrated pest management (IPM), which combines natural enemies, resistant varieties, good field practice and selective use of pesticides.

Can Lacewings Hear Bats?

Yes, many green lacewings can detect the ultrasonic calls of hunting bats, using a tiny hearing organ at the base of the forewing, and they respond by folding their wings and dropping out of the air. This ability is an excellent example of an evolutionary arms race between night-flying insects and bats.

Lacewings also communicate. During courtship, males and females of many species tremble their abdomens to send vibration “songs” through the plant, and each species has a characteristic pattern. Closely similar-looking lacewings can therefore be separate species that identify one another by these substrate-borne duets, something researchers now use to tell species apart.

Are Green Lacewings Harmful to Humans?

Green lacewings are not harmful to humans, as they do not bite, sting or damage crops or stored goods. Adult lacewings sometimes release a faint, unpleasant smell when handled, a defence that deters small predators but poses no danger. Larvae may nip a hand if held roughly, but the bite is mild and rarely noticed.

A swarm of lacewings around indoor lights after the monsoon is a nuisance but not a hazard. Switching off lights, using screens and removing the insects gently is enough, and it is better not to spray them, since the species is a beneficial predator of garden pests.

How Can You Encourage Lacewings in a Garden or Farm?

You can encourage lacewings by growing nectar-and-pollen plants, limiting broad-spectrum insecticides and tolerating a small number of aphids that feed the larvae. A garden with flowering herbs, a variety of shrubs and no routine spraying will usually attract and keep these insects.

• Plant small-flowered species such as coriander, fennel, marigold and sunflower near vegetables.
• Avoid broad-spectrum sprays that kill beneficial insects along with pests.
• Accept a low level of aphids, since larvae need food to survive.
• Use gentle options such as a water jet or neem-based products when treatment is needed, and avoid spraying where eggs are visible.
• Leave leaf litter and hedges as shelter for adults in the dry season.

Bottom Line

The green lacewing is a graceful, golden-eyed insect whose larvae quietly guard Indian crops and gardens against aphids and other sap-sucking pests. Protecting its habitat and flowers, and reducing indiscriminate spraying, is the most practical way to benefit from its work.

Frequently Asked Questions

What is a green lacewing?

A green lacewing is a delicate, pale-green insect of the family Chrysopidae, with golden eyes and transparent, net-veined wings. Its larvae, called aphid lions, are predators that feed on aphids and other soft-bodied pests. The adults mainly feed on nectar, pollen and honeydew.

Why are lacewing larvae called aphid lions?

Lacewing larvae are called aphid lions because they hunt and eat large numbers of aphids with their sickle-shaped jaws. They also feed on whiteflies, mealybugs, thrips and the eggs of small insects. A single larva can consume hundreds of prey items before pupating.

Are green lacewings good for gardens and farms?

Yes, green lacewings are good for gardens and farms because their larvae feed on many common sap-sucking pests. They are used in biological control and integrated pest management in several countries, including India. Their usefulness is greatest when growers limit broad-spectrum pesticides and provide flowers for the adults.

Why do lacewing eggs hang on tiny stalks?

Lacewing eggs hang on thin silk stalks to keep them away from crawling predators and from cannibalistic siblings. The stalk lifts the egg off the leaf surface and delays contact between the larva and its neighbours. This increases the chance that newly hatched larvae will survive.

Do green lacewings bite or sting?

No, green lacewings do not sting and are not dangerous to people. Adults are harmless, though they may release a faint odour when handled. Larvae have strong jaws for small prey but rarely bite humans, and any nip is mild.

How long does a green lacewing live?

A green lacewing completes its life cycle from egg to adult in roughly a month in warm conditions, though this varies with temperature and food. The adult may live several weeks to a few months, depending on the species and season. Several generations can be produced in a single year in warm parts of India.

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