| Green lacewings | |
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| Chrysopa perla | |
Scientific classification | |
| Kingdom: | Animalia |
| Phylum: | Arthropoda |
| Class: | Insecta |
| Order: | Neuroptera |
| Superfamily: | Chrysopoidea |
| Family: | Chrysopidae |
| Subfamilies | |
Green lacewings areinsects in the largefamilyChrysopidae of theorderNeuroptera. There are about 85genera and (differing between sources) 1,300–2,000species in this widespread group. Members of thegeneraChrysopa andChrysoperla are very common inNorth America andEurope; they are very similar[1] and many of their species have been moved from one genus to the other time and again, and in the nonscientific literature assignment toChrysopa andChrysoperla can rarely be relied upon. Since they are the most familiar neuropterans to many people, they are often simply called"lacewings". Since most of the diversity of Neuroptera are properly referred to as some sort of "lacewing",common lacewings is preferable.[citation needed]
Green lacewings are delicate insects with a wingspan of 6 to over 65 mm, though the largest forms aretropical. They are characterized by a widecostal field in their wingvenation, which includes the cross-veins. The bodies are usually bright green to greenish-brown, and thecompound eyes are conspicuouslygolden 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 forChrysopa species but also for others (e.g.Cunctochrysa) refers to their ability to release a vile smell from pairedprothoracic glands when handled.[citation needed]
Adults havetympanal organs at the forewings' base, enabling them to hear well. SomeChrysopa show evasive behavior when they hear abat'sultrasound calls: when in flight, they close their wings (making theirecholocational 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 identicalmorphologically may sometimes be separated more easily based on their mating signals. For example, the southern EuropeanChrysoperla mediterranea looks almost identical to its northern relativeC. carnea, but their courtship "songs" are very different; individuals of one species will not react to the other's vibrations.[2]
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Adults arecrepuscular ornocturnal. They feed onpollen,nectar andhoneydew supplemented withmites,aphids and other smallarthropods, and some, namelyChrysopa, are mainlypredatory. Others feed almost exclusively on nectar and similar substances, and havesymbiotic yeasts in their digestive tract to help break down the food intonutrients.[1]
Larvae have either a more slender "humpbacked" shape with a prominent bulge on thethorax, or are plumper, with long bristles jutting out from the sides. These bristles will collect debris and food remains – the emptyinteguments ofaphids, most notably – that providecamouflage from birds.[citation needed]
Eggs are deposited at night, singly or in small groups; one female produces some 100–200 eggs. Eggs are placed on plants, usually whereaphids 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 larvaemoult, then crawl up the egg stalk to feed. They are voracious predators, attacking most insects of suitable size, especially soft-bodied ones (aphids,caterpillars and other insectlarvae, 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 relatedantlions. 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. Theirmaxillae 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 acocoon takes about 1–3 weeks; species fromtemperate regions usually overwinter as aprepupa, thoughC. carnea overwinters as newly hatched adults.[citation needed]
While depending on species and environmental conditions, some green lacewings will eat only about 150 prey items in their entire lives, in other cases 100 aphids will be eaten in a single week. Thus, in several countries, millions of such voracious Chrysopidae are reared for sale asbiological control agents of insect andmite pests in agriculture and gardens. They are distributed as eggs, since as noted above they are highly aggressive andcannibalistic in confined quarters; the eggs hatch in the field. Their performance is variable; thus, there is interest in further research to improve the use of green lacewings asbiological pest control. Species that have hitherto attracted wider study and are more or less readily available as captive-bred eggs to deposit out for hatching in pest-infested plant cultures are several members ofChrysoperla as well asMallada signatus.[4] They are a natural predator of theEuropean corn borer, a moth that costs the US agriculture industry more than $1 billion annually in crop losses and population control.[5][6]
Gardeners can attract these lacewings – and therefore ensure a steady supply of larvae – by using certaincompanion plants and toleratingbeneficial weeds. Chrysopidae are attracted mainly byAsteraceae – e.g.calliopsis (Coreopsis),cosmos (Cosmos),sunflowers (Helianthus) anddandelion (Taraxacum) – andApiaceae such asdill (Anethum) orangelica (Angelica).[citation needed]
For a long time, green lacewings were considered close relatives of the pleasing lacewings (Dilaridae) and brown lacewings (Hemerobiidae) and placed in thesuperfamilyHemerobioidea. Belam But this grouping does not appear to be natural and misled most significantly by the supposed hemerobioideans'plesiomorphiclarvae. Today, the Hemerobioidea are usually consideredmonotypic, 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 superfamilyOsmyloidea – also monotypic following the spongillaflies' removal from there – is the closest living relative of green lacewings; someMesozoic taxa have been placed in families even closer to Chrysopidae (Ascalochrysidae andMesochrysopidae) and united with these to superfamilyChrysopoidea.[7]
The living genera of Chrysopidae are divided into one very large and two smallersubfamilies; 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 thebasal radiation of theChrysopoidea must have happened in theJurassic already, if not earlier.[citation needed]
There are over 60 genera placed in four tribes:
Information on localities of fossil chrysopids is taken from thePaleobiology Database unless otherwise noted.
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