Summary

Lacewings have elongated, slender bodies with prominent, bulging eyes. They measure 1 to 3 centimeters in length, varying by species. Their transparent wings have a delicate, net-like pattern resembling lacework. Wings are held over the body in a 'tent' formation when at rest. Their antennae are long and thread-like, extending outward from the sides of their head.

There are two important lacewing families that occur in Australia. These are the 'green lacewings' (Chrysopidae) and the 'brown lacewings' (Hemerobiidae).

Brown Lacewings

Brown lacewings, both adults and larvae, are predatory. They are distributed throughout all regions of Australia and can be found in most habitats. In broad-acre crops, their presence is more prominent during the spring to autumn period, spanning from September to April.

The eggs of brown lacewings are elongated-oval, measuring approximately 1/25 inch (1 mm) or less in length. They are gray, pink, or whitish and have a finely pitted surface. These eggs can be found near dense pest infestations, as well as in crevices, bark pits, around buds, or on twigs.

Larvae of brown lacewings are elongated with distinctive brown and cream markings. They reach a length of about 5 mm and are equipped with large, sickle-shaped mandibles, which they utilize to capture their prey. The larvae are highly active and mobile.

Green Lacewings

Green lacewings have a diet consisting of pollen and nectar during adulthood, while their larvae are predatory. Although noticed less than brown lacewings, they are also common in most habitats, and they can be bought commercially.

Green lacewings commonly position their eggs in a U-shape on the undersides of leaves. Adult females can lay up to 600 eggs within their three-to-four week lifespan. Notably, these eggs are deposited on hair-like stalks, possibly as a means of protecting them from predators.

The larvae of green lacewings have a brown to pinkish coloration and possess a tapering abdomen. They can grow to a length of 6-8 mm. Many species of green lacewing larvae employ debris, such as the remains of their prey, as camouflage by attaching it to their backs using long, curved hairs. These larvae are highly active, and have large sickle-shaped mandibles, which they use to catch their prey.

Diet

Lacewings attack aphids, thrips, mites, caterpillars and moth eggs. Brown lacewing adults and larvae are both predatory. Green lacewing larvae are predatory, but green lacewing adults are not predacious, they eat pollen, nectar and honeydew.

Pests Attacked*

Monitoring guidelines

Adult lacewings, eggs, and larvae can be visually monitored in crops. The eggs of the green lacewings are visually distinctive due to their white colour and long slender stalks. Lacewing larvae can also be visually spotted in association with aphid colonies and other pest infestations.

Adult lacewings can be collected through the use of sweep nets, whilst a beat sheet is effective in collecting lacewing larvae.

Sweep net: Hold the handle of the sweep net and make sweeping motions through crop. Move the net back and forth in a semi-circular or figure-eight pattern to capture insects present in the vegetation.

Beat Sheet: A sheet between 1.3-1.5 m wide by 1.5-2.0 m deep, made of yellow or white tarpaulin with a sturdy stick attached to each end. To use it, place one edge of the sheet at the base of the plants in the row you want to check. Hang the other end over the adjacent row or against the base of the next row for wider spacings. Hold the stick at both ends and shake the plants vigorously 5-10 times to dislodge insects onto the sheet. This process should be repeated at four different non-consecutive lengths of row within a 20-meter radius.

Habitat management

Lacewings are commonly released in crops, orchards, nurseries, parks, and gardens. Establishing a breeding population of lacewings can provide long-term pest management solutions.

Although lacewings may not establish themselves readily in protected crops or low-growing vegetation, targeted treatment of lacewing larvae can still yield highly favorable outcomes in such scenarios.

Creating diverse habitats with hedgerows, cover crops, brushpiles and wildflower strips can support generalist predator population, by providing additional food sources, nesting sites, and protection from pesticide exposure or extreme weather conditions. Lacewings tend to be less competitive than other specialist pests, so this supports their populations when pest pressure within the crops is low.

Lacewings are particularly attracted to flowers with umbelliferous and daisy-like structures. Some examples of such flowers include alyssum, dill, calendula, angelica, golden marguerite, coriander, cosmos, Queen Anne's lace, yarrow, fennel, tansy, and dandelion.

Excessive use of pesticides can be detrimental to lacewing populations and their effectiveness as biological control agents. Consider adopting integrated pest management (IPM) practices, which involve using pesticides judiciously and as a last resort. Targeted application of pesticides, avoiding broad-spectrum ones, and selecting insecticides that have minimal impact on non-target organisms can help preserve lacewing populations.

Chemical toxicity

To assist growers and advisors in making informed choices around insecticide use in Australian grain crops, the below table summarises the toxicity of foliar chemical sprays on lacewings.

The impact ratings in the table are colour-coded, indicating the level of impact on beneficial insects. The colour scheme is as follows:

• Green: low impact (<30% mortality)
• Yellow: moderate impact (30-79% mortality)
• Orange: high impact (80-99% mortality)
• Red: very high impact (>99% mortality)

Data shown here is directly from the Beneficials Chemical Toxicity Table.

Ratings for toxicity are based on International Organisation for Biological Control (IOBC) protocols for laboratory studies and reflect percent mortality of insects.

These values represent mortality under controlled laboratory conditions – impacts may vary in the field, especially if multiple applications of a chemical occur.