Chrysopidae

Head close-up of Apertochrysa edwardsi from Austins Ferry, Tasmania, Australia

Green lacewings are delicate insects with a wingspan of 6 to over 65 mm, though the largest forms are tropical. They are characterized by a wide costal field in their wing venation, which includes the cross-veins. The bodies are usually bright green to greenish-brown, and the compound eyes are conspicuously golden in many species. The wings are usually translucent with a slight iridescence; some have green wing veins or a cloudy brownish wing pattern. The vernacular name "stinkflies", used chiefly for Chrysopa species but also for others (e.g. Cunctochrysa) refers to their ability to release a vile smell from paired prothoracic glands when handled.

Adults have tympanal organs at the forewings' base, enabling them to hear well. Some Chrysopa show evasive behavior when they hear a bat's ultrasound calls: when in flight, they close their wings (making their echolocational signature smaller) and drop down to the ground. Green lacewings also use substrate or body vibrations as a form of communication between themselves, especially during courtship. Species which are nearly identical morphologically may sometimes be separated more easily based on their mating signals. For example, the southern European Chrysoperla mediterranea looks almost identical to its northern relative C. carnea (Common Green Lacewing), but their courtship "songs" are very different; individuals of one species will not react to the other's vibrations.[2]

Larva of unknown species (from Latvia) camouflaged with sand grains

Adults are crepuscular or nocturnal. They feed on pollen, nectar and honeydew supplemented with mites, aphids and other small arthropods, and some, namely Chrysopa, are mainly predatory. Others feed almost exclusively on nectar and similar substances, and have symbiotic yeasts in their digestive tract to help break down the food into nutrients.[1]

Larvae have either a more slender "humpbacked" shape with a prominent bulge on the thorax, or are plumper, with long bristles jutting out from the sides. These bristles will collect debris and food remains – the empty integuments of aphids, most notably – that provide camouflage from birds.

Stalked eggs of unknown species, Mainzer Sand (Rhineland-Palatinate, Germany)

Larva of Common Green Lacewing (Chrysoperla carnea) or perhaps C. mediterranea feeding on an aphid

Eggs are deposited at night, singly or in small groups; one female produces some 100–200 eggs. Eggs are placed on plants, usually where aphids are present nearby in numbers. Each egg is hung on a slender stalk about 1 cm long, usually on the underside of a leaf. Immediately after hatching, the larvae moult, then crawls up the egg stalk to feed. They are voracious predators, attacking most insects of suitable size, especially soft-bodied ones (aphids, caterpillars and other insect larvae, insect eggs, and at high population densities also each other). The larvae may also occasionally bite humans, possibly out of either aggression or hunger.[3] Therefore, the larvae are colloquially known as "aphid lions" (also spelled "aphidlions") or "aphid wolves", similar to the related antlions. Their senses are weakly developed, except that they are very sensitive to touch. Walking around in a haphazard fashion, the larvae sway their heads from one side to the other, and when they strike a potential prey object, the larva grasps it. Their maxillae are hollow, allowing a digestive secretion to be injected in the prey; the organs of an aphid can for example be dissolved by this in 90 seconds. Depending on environmental conditions, pupation which takes place in a cocoon takes about 1–3 weeks; species from temperate regions usually overwinter as a prepupa, though C. carnea overwinters as newly hatched adults.

Chrysopa sp.

For a long time, green lacewings were considered close relatives of the pleasing lacewings (Dilaridae) and brown lacewings (Hemerobiidae) and placed in the superfamily Hemerobioidea. But this grouping does not appear to be natural and misled most significantly by the supposed hemerobioideans' plesiomorphic larvae. Today, the Hemerobioidea are usually considered monotypic, containing only the brown lacewings; the green lacewings seem to be very closely related to the osmylids (Osmylidae), which have much more advanced larvae superficially resembling those of the spongillaflies (Sisyridae) with which the spongillaflies were thus formerly allied. Thus the superfamily Osmyloidea – also monotypic following the spongillaflies' removal from there – is the closest living relative of green lacewings; some Mesozoic taxa have been placed in families even closer to Chrysopidae (Ascalochrysidae and Mesochrysopidae) and united with these to superfamily Chrysopoidea.[7]

Paleochrysopa monteilsensis holotype wing

Nothochrysa fulviceps (Nothochrysinae)

Nothancyla verreauxi (Apochrysinae)

The living genera of Chrysopidae are divided into one very large and two smaller subfamilies; a few genera are not robustly assigned to either of these yet. Compared to other Neuroptera, which have an extensive, sometimes extremely abundant, fossil record, green lacewings are not known from that many fossils, and these are not generally well-studied.[1] Their prehistoric relatives mentioned above, however, indicate that at least the basal radiation of the Chrysopoidea must have happened in the Jurassic already, if not earlier.

• Engel, Michael S. & Grimaldi, David A. (2007): The neuropterid fauna of Dominican and Mexican amber (Neuropterida, Megaloptera, Neuroptera). American Museum Novitates 3587: 1–58. PDF fulltext
• New, T. R. (2002): Prospects for extending the use of Australian lacewings in biological control. Acta Zoologica Academiae Scientiarum Hungaricae 48(Supplement 2): 209–216. PDF fulltext
• Winterton, S. L. & Brooks, S. J. (2002): Phylogeny of the apochrysine green lacewings (Neuroptera: Chrysopidae: Apochrysinae). Annals of the Entomological Society of America 95(1): 16–28. doi:10.1603/0013-8746(2002)095[0016:POTAGL2.0.CO;2] PDF fulltext

• Brooks, S. J. & Barnard. P. C. (1990): The green lacewings of the world: a generic review (Neuroptera: Chrysopidae). Bulletin of the British Museum of Natural History (Entomology) 59(2): 117–286.
• Penny, N. D.; Adams, P. A.; Stange, L. A. (1997): Species Catalog of the Neuroptera, Megaloptera, and Raphidioptera of America North of Mexico. Proceedings of the California Academy of Sciences 50(3): 39–114.
• Tauber, C. A. (2004): A systematic review of the genus Leucochrysa (Neuroptera: Chrysopidae) in the United States. Annals of the Entomological Society of America 97(6): 1129–1158. doi:10.1603/0013-8746(2004)097[1129:ASROTG2.0.CO;2]
• Winterton, S. L. (1995): A new genus and species of Apochrysinae (Neuroptera: Chrysopidae) from Australia, with a checklist of Australian Chrysopidae. Journal of the Australian Entomological Society 34(2): 139–145. doi:10.1111/j.1440-6055.1995.tb01306.x

• Media related to Chrysopidae at Wikimedia Commons