Order Neuroptera - Lacewings, Alder Flies & Snake Flies

• Ant-lion
• Green Lacewing
• Alder Fly
• Snake Fly
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Small to large soft-bodied insects, with two pairs of very similar membranous wings covered with a delicate network of veins and held roof-wise over the body at rest. Antennae generally long and thread-like, sometimes with a terminal club. Mouthparts for biting. Abdomen fairly slender, without cerci. There is a complex metamorphosis, with a pupal stage. The larvae are carnivorous, with biting or suctorial mouthparts. This is an ancient Order and contains some of the most primitive living endopterygote insects. Nearly 5,000 species are known, of which about 60 occur in the British Isles.

There are considerable differences, particularly in the young stages, between the Alder Flies and Snake Flies on the one hand and the rest of the Neuroptera on the other. In fact, many entomologists place the insects in two separate Orders. When treated as a single order, the Alder Flies and Snake Flies (whose larval stages have biting mouthparts) are placed in a sub-order called MEGALOPTERA, and the rest of the Neuroptera (Ant-lions, Lacewings, etc., whose larvae have sucking mouthparts) are placed in a sub-order called PLANIPENNIA.

Description. Adult up to 35-40 mm long, superficially like a dragonfly, but easily distinguished by its stout, clubbed antennae and much slower flight. Wings of some species with dark brown flecks. Larva greyish-brown, up to 12 mm long, with large powerful jaws curving inwards at the tips and a broad oval body.

Biology. Found in sandy places. The adults fly with a lazy rising and falling motion and rarely move far at any one time. The name 'Ant-lion' refers to the larva. This lives in sandy soil and excavates a small pit. It buries itself at the bottom, leaving only its strong jaws above the sand. When passing insects fall into the pit they slip to the bottom on the loose sand and are quickly seized by the ant-lion and sucked dry. The pits of full-grown larvae are up to 5 cm deep and 8 cm across. Larvae take two years to complete their development.

Distribution. Europe.

Photos: (adult) Cotinis, CCA Share Alike License; (larva & pits) V.J. Stanek ©

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Adult

Larva

Larval pits

Description. Adult about 15 mm long, with the body and wing veins a delicate shade of green. The prominent eyes have a bright metallic appearance. Larva up to 12 mm long, mottled brown, with long curved jaws.

Biology. Both adults and larvae are important natural enemies of aphids (greenfly, blackfly, etc.) and can provide a biological control of these plant pests.

Distribution. Europe, including the British Isles (similar species occur in parts of Africa, Asia and North America).

Photo: A. Feininger ©

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Description. Adult about 10-15 mm long and dark brown in colour. Wings with prominent dark veins. Larva up to 25 mm long, also dark brown, with strongly sclerotised head and thorax and well developed, pincer-like jaws; abdomen with seven pairs of jointed tracheal gills and a single terminal filament of similar appearance.

Biology. Adults found close to ponds and slow-flowing streams where there is plenty of silt for the aquatic larvae. The adults are weak fliers and live for just two to three days, during which time they do not feed and spend most of their time hiding amongst vegetation. The emergence of adults is synchronised, so that large numbers of both sexes are present at the same time. Mating occurs at night and eggs are laid in batches of 200 or more around the waterside, often on overhanging foliage. After hatching, the larvae fall or crawl into the water. They live on the bottom, under stones or buried in silt or decaying vegetation, where they feed on a wide range of smaller aquatic insects, worms and other small invertebrates. Mature larvae leave the water in spring and pupate in nearby damp soil or leaf litter; adults emerge a few weeks later, usually in May-June. The life-cycle takes 1-2 years.

Distribution. British Isles and parts of Europe.

Photo: (adult) Entomart ©; (larva) Andre Karwath, CCA Share Alike License

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Adult

Larva

Description. Adult about 10-12 mm long and dark brown in colour. Easily recognised by the long thorax, which can raise the head above the rest of the body in the manner of a snake about to strike. The female has a long, tail-like ovipositor at the end of the abdomen. The larva is also brown, with a slender, elongated body, narrow thorax and short, but strong, biting jaws.

Biology. Generally found on trees, especially in oak woodland. The female uses her long ovipositor to lay eggs deep in the cracks and crevices of tree bark. The larvae live mainly under loose bark, where they feed on other insects. They can be important predators of insect pests, such as aphids, scale insects and bark beetle larvae.

Distribution. British Isles and parts of Europe.

Photo: Beentree, GNU Free Documentation License

Adult female, with long ovipositor