Neuroptera is an order of insects whose members share a defining trait: two pairs of large, intricately veined wings that fold tent-like over the body at rest, giving rise to the common name “lacewings.” The order encompasses roughly 6,000 described living species, including familiar groups like green lacewings, brown lacewings, antlions, owlflies, and mantidflies. Despite their delicate adult appearance, neuropterans are united by a far more aggressive feature: nearly all of them spend their larval stage as voracious predators equipped with specialized piercing mouthparts found nowhere else in the insect world.
Where Neuroptera Fit in the Insect Tree
Neuroptera belongs to a broader grouping called Neuropterida, a superorder that also includes Megaloptera (dobsonflies and alderflies) and Raphidioptera (snakeflies). All three orders undergo complete metamorphosis and share deep evolutionary roots. Over the past few decades, studies combining adult and larval anatomy with mitochondrial and nuclear DNA have converged on similar family trees, many of which echo hypotheses first proposed by the English entomologist Cyril Withycombe in the 1920s.1PubMed. Phylogeny and Evolution of Neuropterida: Where Have Wings of Lace Taken Us? A large-scale genomic analysis found that snakeflies (Raphidioptera) are the sister group to a clade formed by Neuroptera plus Megaloptera, meaning lacewings and dobsonflies are each other’s closest relatives within the superorder.2PubMed Central. An integrative phylogenomic approach to elucidate the evolutionary history and divergence times of Neuropterida (Insecta: Holometabola)
Resolving relationships within Neuroptera itself has been trickier, partly because the order is ancient and its many lineages diversified rapidly. Different data sets sometimes yield conflicting trees, especially when compositional biases in DNA sequences mislead the analysis. Recent work integrating multiple genomic approaches has started to reconcile those conflicts, offering what researchers describe as a “holistic phylogeny” of Neuropterida from which to explore broader evolutionary patterns.3Palaeoentomology. Improved modelling of compositional heterogeneity reconciles phylogenomic conflicts among lacewings
Ancient Pollinators That Looked Like Butterflies
One of the more striking chapters in neuropteran evolution involves the kalligrammatid lacewings, an extinct family that appeared in the fossil record about 165 million years ago and vanished sometime in the Late Cretaceous. These insects independently evolved wing eyespots, wing scales, and long tubular mouthparts for reaching into the pollination drops of seed plants, making them startlingly similar to modern butterflies despite being only distantly related.4PubMed Central. The evolutionary convergence of mid-Mesozoic lacewings and Cenozoic butterflies Kalligrammatids lived in ecosystems dominated by gymnosperms (plants like conifers and bennettitales, rather than flowering plants), and their convergent butterfly-like anatomy is a textbook example of how similar ecological pressures can independently sculpt similar body plans.
For a long time, paleontologists assumed kalligrammatids died out during a mid-Cretaceous gap in the fossil record, roughly 125 to 100 million years ago. But amber fossils have since pushed the group’s latest known occurrence further forward, showing that kalligrammatids were still diverse in the Late Cretaceous.5Nature Communications. High niche diversity in Mesozoic pollinating lacewings Their eventual disappearance may have coincided with the explosive rise of flowering plants and the modern butterfly lineages that would come to fill the same pollination niches.
The Larval Weapon That Defines the Order
If there is one thing that makes neuropteran larvae unmistakable, it is their mouthparts. Unlike caterpillars that chew leaves or fly maggots that absorb liquified food, neuropteran larvae have mandibles and maxillae that interlock to form a pair of hollow, sickle-shaped stylets. The mandibles do the piercing, while the maxillae slide alongside them to create a food canal through which digestive fluids are injected and liquified prey tissue is sucked back up.6PubMed Central. A 100-million-year old predator: a fossil neuropteran larva with unusually elongated mouthparts This mandible-maxilla complex is the ancestral condition for the entire order, and the curved shape of the stylets is itself functional: the two sides counteract each other, generating the force needed to puncture prey without requiring a rigid skull to push against.
High-speed imaging of antlion larvae feeding has revealed just how precisely this system works. The maxillae perform rapid antiparallel sliding movements, exposing a hydrophilic food canal that otherwise stays sealed and protected from sand and debris. The canal’s interior is lined with tiny cuticular projections that help move fluids and small particles along its length. Meanwhile, the outer surfaces of the mouthparts are hydrophobic, creating a wetting contrast that keeps the feeding channel functional even in gritty environments.7Journal of Experimental Biology. Mouthpart adaptations of antlion larvae facilitate prey handling and fluid feeding in sandy habitats
Lacewing Venom Is More Than Digestive Fluid
For decades, researchers assumed that neuropteran larvae simply injected digestive enzymes to dissolve their prey’s innards. That is part of the story, but recent research on the common green lacewing Chrysoperla carnea has shown that the secretion is a genuine venom: a complex cocktail that not only digests tissue but actively paralyzes prey. When tested on fruit flies, the venom produced a consistent paralytic effect, and individual lacewing larvae carry enough venom in their glands to paralyze a fly-sized insect with only a fraction of their total supply.8Molecular Biology and Evolution. The green lacewing venom system and the complex mechanisms underlying its evolution This finding elevates neuropteran larvae from simple fluid-feeders to true venomous predators, placing them in a broader conversation about venom evolution across the arthropod tree.
Antlion Pit Traps and the Physics of Sand
Antlions, the larvae of the family Myrmeleontidae, are probably the most famous neuropterans, and for good reason. The cone-shaped pitfall traps they dig in dry sand are miniature feats of engineering, maintained at slopes just barely below the angle at which the sand would collapse on its own. An insect that steps over the rim immediately starts sliding toward the waiting jaws at the bottom.
Laboratory experiments combined with computer modeling have shown that antlion sand-throwing serves a more specific purpose than simply bombarding struggling prey. By flicking sand grains from the center of the pit, the larva continuously removes material that accumulates at the base, keeping the walls steep. Measurements show the average slope angle of a pit increases significantly after sand-throwing, rising from about 27° to about 31°, effectively maintaining the trap in a near-unstable state where any disturbance sends sand cascading inward.9PubMed Central. Sand-throwing behaviour in pit-building antlion larvae: insights from finite-element modelling The resulting sandslides do double duty: they keep the trap efficient and physically drag trapped prey back toward the center when it tries to climb out.
Not all antlion pits are simple cones, either. The species Cueta lineosa builds pits with a distinctive two-tier geometry: a broad, shallow primary cone near the surface, and a narrower, steeper secondary cone excavated deeper into the substrate. This contrasts with the more common single-cone design seen in species like Myrmeleon hyalinus. The difference in shape is tied to the particle size of the available sand, with finer grains enabling more complex architectures.10Journal of Experimental Biology. Fine sand particles enable antlions to build pitfall traps with advanced three-dimensional geometry
Trash Armor and Deep-Time Camouflage
Many green lacewing larvae have a habit that looks bizarre until you understand its purpose: they pile the carcasses of their prey, bits of plant material, sand grains, and other debris onto elongated hooked setae on their backs, building a “trash packet” that covers their body. This is not mere sloppiness. Controlled experiments pitting trash-carrying lacewing larvae against predatory ladybirds found that the armor dramatically reduced both detection and capture. Ladybirds attacked trash-covered larvae only about half as often as naked ones, and when they did attack, they managed to capture the debris-clad larvae less than a fifth of the time, compared to more than four-fifths for unprotected larvae.11Applied Entomology and Zoology. Defensive functions of the trash-package of a green lacewing, Mallada desjardinsi (Neuroptera: Chrysopidae), against a ladybird, Harmonia axyridis (Coleoptera: Coccinellidae) The trash packet works on two levels: it hides the larva’s outline (making it unrecognizable as prey) and it physically impedes the predator’s grip.
This behavior is not a recent invention. A chrysopid larva preserved in Early Cretaceous Lebanese amber, roughly 130 million years old, was found carrying a debris packet composed of soil particles tangled in extremely elongate tubular tubercles on its back, essentially the same anatomy and behavior seen in living species today.12PubMed Central. A soil-carrying lacewing larva in Early Cretaceous Lebanese amber The persistence of this strategy across more than 100 million years suggests it provides a strong and consistent survival advantage.
Mantidflies and Their Raptorial Forelegs
Among the more unusual neuropteran lineages are the mantidflies (Mantispidae), which as adults look superficially like praying mantises: elongate prothorax, large raptorial front legs held up in an ambush posture. Despite looking the part, mantidflies are lacewings through and through. A trove of mid-Cretaceous amber fossils from Myanmar has revealed that ancient mantidflies were far more diverse in their foreleg designs than living species. Some possessed forked spines at the base of the femur; others had lost spine-like structures on the forelegs entirely. This range of raptorial modifications, some of which have no modern equivalent, hints at a wider spectrum of predatory strategies that has narrowed over the past 100 million years.13PubMed Central. Cretaceous diversity and disparity in a lacewing lineage of predators (Neuroptera: Mantispidae)
Modern mantidflies already have remarkably varied life histories. Some species lay their eggs near spider egg sacs, and the first-instar larvae burrow inside to feed on spider eggs, completing their development as parasitoids before emerging as free-living adults. Others are straightforward ambush predators. The Cretaceous fossils suggest that this diversity of ecological roles was, if anything, even greater in the deep past.
Singing Through the Stems
Adult green lacewings in the Chrysoperla carnea species group are a classic example of cryptic species: populations that look virtually identical under a microscope but are reproductively isolated because they sing different songs. The “singing” is not airborne sound. Instead, the adults vibrate their abdomens up and down against the plant stem they are standing on, producing substrate-borne vibrational signals that travel through the leaf or twig. Potential mates answer with their own vibrational duet, and only individuals whose songs match will pair up.
High-speed video has shown that the abdomen’s motion during singing is driven by neuromuscular elements that simultaneously generate two or more tones of different frequency. The waveform measured in the plant stem does not exactly mirror the abdomen’s motion, because the plant filters the signal, but the frequencies stay the same.14Journal of Insect Behavior. Courtship Songs of Green Lacewings Filmed in Slow Motion: How a Simple Vibrating Structure can Generate Complex Signals (Neuroptera: Chrysopidae: Chrysoperla) Comparing how different species move their abdomens while generating distinct tones lets researchers identify which song elements are shared across species (and thus likely inherited from a common ancestor) versus which are novel. This vibrational communication system has driven rapid speciation within the group, producing a cluster of genetically and behaviorally distinct species that would otherwise be lumped together by anyone relying on appearance alone.
Dropping Out of the Sky to Dodge Bats
Green lacewings are largely nocturnal fliers, which puts them squarely in the hunting zone of echolocating bats. Their countermeasure is abrupt and effective: when a flying lacewing detects ultrasound, it folds its wings and drops. The behavioral sequence is fast. Wing-folding begins about 40 milliseconds after the ultrasound stimulus, and flight-muscle activity ceases about 66 milliseconds after that. The insect essentially goes limp and plummets, making itself a much harder target for a bat executing a high-speed interception. After the ultrasound stops, the lacewing resumes flight. This response occurs consistently only at night, which is when bats hunt and when lacewings are actually airborne.15Journal of Insect Physiology. The behaviour of flying green lacewings, Chrysopa carnea, in the presence of ultrasound
The underlying hearing organ is a simple swelling at the base of a wing vein, yet it is tuned precisely to the frequency range of bat echolocation calls. Moths famously have a similar anti-bat response, but lacewings evolved theirs independently, using a completely different anatomical structure. It is one more case of convergent evolution driven by a shared predator.
Silk From an Unexpected Organ
Most insects that spin silk do so from modified salivary glands, but neuropteran larvae are different. In the family Chrysopidae, the silk used to construct pupal cocoons is produced by the Malpighian tubules, the same organs that normally handle excretion and water balance. When a mature larva is ready to pupate, the Malpighian tubules switch function and extrude silk threads that the larva weaves into a spherical cocoon.
This unusual arrangement makes the cocoon-spinning process especially vulnerable to certain pesticides. The insect growth regulator pyriproxyfen, for instance, causes structural damage to the Malpighian tubule cells of the green lacewing Ceraeochrysa claveri, including loss of microvilli and cytoplasmic injury. Exposed larvae produce compromised cocoons, reducing their chances of successful metamorphosis.16PubMed. Pyriproxyfen exposure compromises cocoon spinning and damages the Malpighian tubules of the nontarget predator Ceraeochrysa claveri (Neuroptera: Chrysopidae) Because green lacewings are widely used in pest management as beneficial predators, pesticides that damage their silk-producing organs can undermine the very biological control programs they are supposed to support.
Lacewings in Pest Management
Green lacewings are among the most commercially produced beneficial insects in the world. Their larvae are generalist predators that will eat aphids, whiteflies, mealybugs, thrips, and small caterpillars, making them useful across a wide range of crops. In laboratory trials, a single larva of the Chinese green lacewing Chrysopa sinica consumed over 1,200 one-day-old cotton aphids across its entire larval development.17Insect Science. Energy budgets of the Chinese green lacewing (Neuroptera: Chrysopidae) and its potential for biological control of the cotton aphid (Homoptera: Aphididae) That appetite is why growers release lacewing eggs or larvae directly into greenhouses and field crops.
A limiting factor in mass-rearing lacewings has always been the cost of live prey to feed them. The standard laboratory food source is eggs of the Mediterranean flour moth, which are expensive to produce at scale. Researchers have tested various artificial diets to reduce this dependency. For the species Chrysoperla externa, one optimized artificial diet allowed larvae to complete second and third instars without live prey, cutting reliance on moth eggs by about 90%.18PubMed. Rearing Chrysoperla externa Larvae on Artificial Diets Similar diet development for Mallada basalis, an economically important species in Asia, has also shown that modified artificial formulations can support both larval development and adult reproduction.19PLoS ONE. Rearing of Mallada basalis (Neuroptera: Chrysopidae) on modified artificial diets
Feeding adults is its own challenge, since some lacewing species are predatory as adults rather than just as larvae. For the goldeneye lacewing Chrysopa oculata, experiments testing five protein supplements across six consecutive generations found that moth eggs remained the most suitable option, supporting the highest number of successive generations.20PubMed. Artificial adult diet for Chrysopa oculata (Neuroptera: Chrysopidae) to overcome the barriers to rearing predatory adult green lacewings The search for a fully synthetic, cost-effective lacewing diet is still ongoing.
An additional wrinkle is that the quality of the crop itself affects how many aphids a lacewing needs to eat. When plants are heavily fertilized with nitrogen, aphids grow larger and more nutrient-dense, and lacewing larvae eat fewer of them while still consuming roughly the same total biomass. On low-nitrogen plants, aphids are smaller, and lacewing larvae compensate by consuming more individuals to get the same nutrition.21PubMed. Effect of plant nutrition on aphid size, prey consumption, and life history characteristics of green lacewing For a grower, this means the number of aphids you see a lacewing eat is not a reliable indicator of how much pest suppression you are getting. What matters is total biomass removed.
Ribbon Wings and Other Anatomical Oddities
Not every neuropteran looks like a typical lacewing. The thread-winged lacewings (Nemopteridae) have hind wings that are elongated into slender, ribbon-like streamers several times the length of the body. These modified hind wings do not contribute to flapping flight in the usual sense; instead, they appear to help the insect glide, stabilize during flight, and possibly assist in escape maneuvers.22Oxford Academic. Theoretical morphospace analysis of neuropteran wings reveals little evidence of optimization for flight performance Thread-winged lacewings are found in arid regions of the Mediterranean, Africa, and Australia, and their appearance in flight is so distinctive that encountering one can be genuinely startling if you are not expecting it.
More broadly, theoretical analyses of neuropteran wing shapes have found surprisingly little evidence that the order’s wings are optimized for flight performance in the aerodynamic sense. This does not mean neuropterans are bad fliers. Rather, it suggests their wing venation has been shaped by other pressures too: structural strength, folding mechanics, and the demands of the pupal wing pad fitting inside a cocoon. The result is a wide range of wing shapes across the order, from the broad, densely veined fans of owlflies to the narrow, almost grass-blade-like wings of some brown lacewings.
Gut Yeasts and Nutritional Partnerships
Green lacewing adults feed on pollen, nectar, and honeydew, a sugar-rich but nutritionally incomplete diet. To help fill the gaps, chrysopid lacewings harbor specific yeasts in their guts. A survey of 58 lacewing adults from nine species across Japan found that every single individual carried yeasts of the genus Metschnikowia, including species from a subfamily (Apochrysinae) that had never been examined before.23PubMed Central. Novel Metschnikowia yeasts from the gut of green lacewing in Japan The universality of this association, with every individual tested hosting gut yeasts, suggests the relationship is obligate rather than accidental. The yeasts likely help synthesize amino acids or B vitamins that a pollen-and-honeydew diet alone cannot provide, though the exact metabolic contributions are still being worked out.
This kind of insect-yeast mutualism is known in other groups (certain beetles and plant-sucking bugs, for example), but its presence across the entire Chrysopidae family, spanning multiple subfamilies and genera, marks it as a deeply rooted partnership rather than a recent evolutionary accident.