Lacewings belong to an ancient order of insects, Neuroptera. Members of this order are diverse in behaviour and appearance, with wingless larvae that are very different from their delicately-winged adult forms.
Adult lacewings can be recognised by their habit of holding the wings tent-like over the body when at rest and by the branching at the end of the main veins in the wings. This branching of wing veins distinguishes them from other similar flying insects such as dragonflies and damselflies (Order Odonata), mayflies (Order Ephemoptera) and alderflies (Order Megaloptera).
Adult lacewings wings vary in colour from bright green to brown, and black.
The mainly carnivorous larvae are diverse in appearance and quite unlike their adult forms. The nymphid lacewing larvae have flattened, disk-shaped bodies fringed with long hair-like projections. Their body shape may be an adaptation for tree-dwelling. Most lacewing larvae use protruding tube-shaped mouthparts to suck up the body fluids of their prey and most have large grasping jaws to help hold their prey.
Some species have burrowing (Family Ithonidae) and parasitic (Family Mantispidae) larvae which are grublike and have short stout jaws. Owlfly larvae (Ascalaphidae) are generalist predators in the leaf litter, and are disc-shaped with finger-like projections along the body which break up their visual outline. Antlions (Family Myrmeleontidae) have stout, hunchbacked bodies adapted for burrowing in sand.
Larvae of the Family Chrysopidae often resemble walking rubbish balls. This is because they attach debris including the husks of their aphid prey to body hairs as a form of camouflage.
Lacewings are found in most habitats in Australia. Both adults and larvae are commonly encountered in urban areas, where the adults are readily attracted to lights.
Feeding and diet
Most adult lacewings are predators, with a few species feeding on nectar or plant material.
The larvae are found on vegetation or in sandy soil in sheltered areas, such as around the bases of trees. They are mostly predacious, feeding on other invertebrates that they encounter. Some feed on decaying vegetable material, fresh water sponges (aquatic species in the Family Spongyliidae) or parasitise spiders or wasps (Family Mantispidae).
Antlions (Family Myrmeleontidae) build cone-shaped ant traps in sheltered sandy areas and wait under the bottom of the trap for an ant to fall in. The loose sandy sides prevent prey from escaping, and the antlion also flicks sand at the struggling ant. The antlion seizes the ant in its powerful jaws and sucks it dry.
The aphid and scale-eating larvae of the families Chrysopidae and Hemerobiidae are highly beneficial insects in crops and gardens. Some of these insects are being commercially produced for release as agricultural biocontrol agents.
Other behaviours and adaptations
Many lacewings produce smells, especially when handled, which may be a defensive response to predation.
Life history cycle
Eggs are commonly laid on stalks, singly or in batches. Some species lay their eggs directly into sand or on vegetation. The eggs often have a distinctive pattern.
Courtship in some species involves the use of sex pheromones and also sound.
Danger to humans
Sometimes larvae of the Family Chrysopidae can cause minor irritation to people working in gardens as they may use their jaws to grasp the skin if handled accidentally.
New, T.R. 1991. Neuroptera. In: Naumann et al. (eds.) Insects of Australia. Melbourne University Press. Australia.