Clearwing moths are a large family of day-flying moths whose wings lack the dense covering of pigmented scales found on most Lepidoptera, leaving broad patches of wing membrane exposed and essentially see-through. The family, Sesiidae, contains over 1,500 described species worldwide, and their transparent wings are only part of a much deeper story. Most clearwing moths are convincing mimics of stinging insects like wasps, hornets, and bees, copying not just their appearance but, as researchers have recently discovered, their flight patterns and even their buzzing sounds.
How a Moth’s Wing Becomes See-Through
A typical moth wing is a thin membrane densely tiled with overlapping scales, like shingles on a roof. Those scales carry the pigments that give moths and butterflies their color, and they also scatter light. Remove or reduce the scales, and the underlying membrane lets light pass through. Different clearwing species arrive at transparency through different developmental routes, and the details turn out to be surprisingly complex.
In some clearwing butterflies (a separate group that has converged on the same trick), transparency involves a loss of pigments in the remaining scales combined with a shift in the scales’ orientation so they stand upright rather than lying flat. The wing membrane itself is coated with a nipple-like array of nanostructures in the outer cuticle layer. In the skipper butterfly Phanus vitreus, for instance, these nipples average about 142 nanometers tall and 135 nanometers across, arranged randomly at a spacing of roughly 300 nanometers. These tiny bumps act as an anti-reflective coating: modeling shows they significantly lower the reflectivity of the wing membrane, allowing more light to pass through rather than bouncing off the surface.
1PubMed Central. Multi-scale dissection of wing transparency in the clearwing butterfly Phanus vitreusNot all transparent-winged Lepidoptera use the same nanostructure recipe. In the famous glasswing butterfly Greta oto, the membrane surface has two layers: a lower layer of regularly arranged nipple nanostructures topped by an irregular upper layer of wax-based nanopillars made mainly of long-chain alkanes.
2PubMed Central. Developmental, cellular and biochemical basis of transparency in clearwing butterfliesThe skipper Phanus vitreus, by contrast, lacks that waxy upper layer entirely.
3PubMed Central. Multi-scale dissection of wing transparency in the clearwing butterfly Phanus vitreusThis tells us that wing transparency has evolved multiple times with somewhat different molecular toolkits, converging on the same visual result.
The Pellucid Hawk Moth and Programmed Scale Loss
Among the Sphingidae (hawk moths), the pellucid hawk moth Cephonodes hylas takes a completely different approach. It emerges from its pupa with a full set of wing scales, then sheds most of them during its very first flights. The transparent patches are not built scale-free from the start; instead, the moth carries a second set of loosely attached “deciduous” scales that are engineered to fall off.
These deciduous scales project outward from the wing surface at a steep angle, over 30 degrees, while the permanent scales lie nearly flat. That steep angle exposes far more of the scale surface to airflow during each wingbeat. Researchers estimated the aerodynamic drag on a deciduous scale is at least three times greater, and possibly eight times greater, than on a flat-lying permanent scale. On top of that, each deciduous scale has a tapered peg that barely inserts into a very small socket in the wing, roughly three micrometers deep compared with the ten-micrometer insertion depth of a permanent scale. Think of it like a tapered cork versus a straight-sided plug: once it starts to shift, the tapered peg loses contact area fast and pops free. The combined effect of higher aerodynamic force and weaker attachment means these scales are essentially spring-loaded for ejection during the first bout of fluttering.
4Zoological Science. Programmed Scale Detachment in the Wing of the Pellucid Hawk Moth, Cephonodes hylas: Novel Scale Morphology, Scale Detachment Mechanism, and Wing TransparencyThis is a striking case of programmed obsolescence in biology. The moth invests resources in building scales only to discard them within minutes of adult life, all in service of looking more like a bumblebee.
Mimicry That Goes Beyond Appearance
The wasp-like or bee-like look of clearwing moths has long been cited as a textbook example of Batesian mimicry, where a harmless species gains protection by resembling a dangerous one. Many sesiid moths have yellow-and-black banded abdomens, narrow wings, and even leg tufts that evoke the fuzzy legs of bees. But appearance is only one channel of deception.
Field studies in Southeast Asian rainforests found that sesiid clearwing moths also mimic the flight trajectories of their hymenopteran models. Bee-mimicking species flew in slow, zigzagging paths that were nearly indistinguishable from those of sympatric stingless bees, while wasp-mimicking species flew faster and straighter, matching the flight style of local wasps.
5PubMed Central. Moving like a model: mimicry of hymenopteran flight trajectories by clearwing moths of Southeast Asian rainforestsThat study represented the first experimental evidence for behavioral mimicry in clearwing moths, and it suggests the mimicry is more finely tuned than a generic “act like a stinging thing” strategy. Different clearwing species appear to match different model species individually.
The mimicry extends to sound as well. Acoustic analysis showed that the buzzing produced by certain Southeast Asian clearwing moths closely resembles the buzz of their model bee, Tetragonilla collina, across eight measured acoustic parameters, while differing from the buzzes of control bee species.
6PubMed Central. Southeast Asian clearwing moths buzz like their model beesSo a predator evaluating a potential meal is getting fooled not just visually but also by the way the moth moves and the sound it makes. It is a remarkably integrated performance.
Does the Mimicry Actually Work on Predators?
The elaborate disguise raises a fair question: do birds actually fall for it? Field experiments testing avian responses found strong evidence that at least some clearwing moth mimicry is effective. European robins showed a clear deterrent reaction to the hornet clearwing moth Sesia apiformis, a mimic of the European hornet Vespa crabro. The birds’ response to the hornet mimic was distinctly different from their reaction to other tested species, strongly suggesting that the presence of a hornet-like insect, whether real or fake, deterred the birds from attacking.
7PubMed Central. Southeast Asian clearwing moths buzz like their model beesNot all mimicry models are wasps and bees. A vivid orange sesiid species described in 2020, Austrosetia piotrii, appears to mimic braconid wasps, with a twist: the braconid wasp it resembles may also be one of its own parasitoids. The moth’s coloration and body posture closely match the wasp, raising the possibility that it is mimicking the very predator that threatens it.
8PubMed Central. A Vivid Orange New Genus and Species of Braconid-Mimicking Clearwing Moth (Lepidoptera: Sesiidae) Found Puddling on Plecoptera ExuviaeThe Squash Vine Borer and Other Agricultural Pests
For gardeners and farmers, clearwing moths are often less fascinating than infuriating. Several sesiid species are serious agricultural pests, and their larval habits make them hard to control. The larvae of most clearwing moths are internal feeders, boring into the stems, trunks, or roots of their host plants, hidden from sight and protected from contact insecticides.
The squash vine borer, Melittia cucurbitae, is one of the most destructive. Its larvae tunnel into cucurbit stems and disrupt the plant’s vascular system, cutting off water and nutrients. In pumpkins, a single larva can reduce yields by about four percent. Three or four larvae push losses above twenty percent, and six or more can kill the plant outright.
9Journal of Integrated Pest Management. Biology and Management of Squash Vine Borer (Lepidoptera: Sesiidae)The adult moth, with its orange-and-black coloring and clear wings, is often mistaken for a wasp by gardeners who do not realize a moth is laying eggs on their squash plants.
Timing control measures against the squash vine borer is tricky because egg-laying stretches across four to six weeks, and the adults are difficult to monitor as the season progresses. In mid-Atlantic pumpkin trials, combining field scouting with pheromone-trap data cut insecticide applications by half while maintaining yields equivalent to weekly spraying.
10Journal of Applied Entomology. Squash vine borer (Lepidoptera: Sesiidae) management in pumpkin in the mid‐AtlanticOther economically important sesiid pests include the peachtree borer and the lesser peachtree borer, both in the genus Synanthedon, which attack stone fruit trees, and the apple clearwing moth, which damages apple and pear orchards in many parts of the world.
Pheromones as a Management Tool
Because clearwing moth larvae live inside plants where sprays cannot reach them, pest management often targets the adults before they lay eggs. Synthetic sex pheromones have become a central tool. Female clearwing moths release species-specific blends of long-chain unsaturated alcohols or acetates to attract males, and chemists have identified these blends for many pest species. The western poplar clearwing, for example, uses roughly a four-to-one ratio of two 18-carbon diene alcohols as its sex attractant.
11Environmental Entomology. Identification of the Sex Pheromone of the Western Poplar Clearwing Moth (Lepidoptera: Sesiidae)These pheromone identifications enable two practical strategies. The first is monitoring: pheromone-baited traps placed in orchards or fields tell growers when adults are flying, helping time sprays to the period of actual egg-laying rather than guessing. For the apple clearwing moth, mass trapping with pheromone-baited traps at densities of 50 to 100 traps per hectare reduced male moth captures in assessment traps, with the main effect being disruption of male orientation toward females.
12Education & Research Archive (ERA), University of Alberta. Semiochemical-based mass trapping of the apple clearwing moth (Synanthedon myopaeformis (Borkhausen)) (Lepidoptera: Sesiidae)The second strategy is mating disruption, where pheromone dispensers are deployed throughout an orchard at high density, flooding the air with synthetic pheromone so males cannot locate real females. In peach orchards, dispensers deployed at 371 per hectare successfully disrupted the mate-finding behavior of both the peachtree borer and the lesser peachtree borer. Larval infestation levels in mating-disruption plots were statistically equivalent to those in plots treated with conventional insecticides.
13PubMed Central. Comparison of Mating Disruption and Insecticide Application for Control of Peachtree Borer and Lesser Peachtree Borer (Lepidoptera: Sesiidae) in PeachMating disruption is appealing because it is species-specific, reduces broad-spectrum insecticide use, and can be deployed once per season.
The chemistry of clearwing moth pheromones is remarkably fine-grained. Even small structural changes to the pheromone molecule can drastically alter biological activity. Studies on the currant clearwing moth tested eleven synthetic analogs of its main pheromone component and found that slight modifications to chain length, double-bond position, or functional group wiped out or greatly reduced the male response.
14PubMed. Structure-activity correlations among analogs of the currant clearwing moth pheromoneThat specificity is what makes pheromone traps so targeted: a lure designed for one clearwing species will generally not attract closely related species, avoiding bycatch of beneficial insects.
Sorting Out Who Is Related to Whom
The Sesiidae family has been a taxonomic headache for entomologists. Because so many species are wasp mimics, their external appearance can be misleading: two moths that look alike may be mimicking the same model species independently rather than being close relatives. Molecular phylogenetics has helped, but the picture remains messy. A multi-gene analysis of 48 North American sesiid species confirmed the traditional tribal groupings within the family but also revealed that two of the largest and most familiar genera, Carmenta and Synanthedon, are paraphyletic, meaning they do not contain all the descendants of their common ancestor. Several smaller genera nest within them.
15PubMed. Multi-gene phylogeny of North American clear-winged moths (Lepidoptera: Sesiidae): a foundation for future evolutionary study of a speciose mimicry complexAn earlier molecular study using mitochondrial DNA from representatives of 10 of the 20 recognized genera found genetic variation ranging from under one percent to over twenty-one percent among species, which gives a sense of the family’s age and diversity.
16Journal of Agricultural and Urban Entomology. Molecular Phylogeny of Sesiidae (Lepidoptera) Inferred From Mitochondrial DNA SequencesThe practical consequence is that entomologists are still working out how many valid species exist and which genera need to be split or merged. For people trying to identify clearwing moths in the field, this means that common names and genus assignments you find in older field guides may not match current classifications.
Transparent Wings as Inspiration for Technology
The nanostructures that make lepidopteran wings transparent or anti-reflective have attracted attention from materials scientists. The nipple arrays on clearwing and glasswing butterfly membranes function as graded-index anti-reflective coatings, smoothing the transition between air and the wing surface so that light is transmitted rather than reflected. Engineers have used similar principles from butterfly wing architectures more broadly to design improved photovoltaic absorbers and photocatalytic surfaces. Nano-patterned absorbers inspired by butterfly wing structures achieved a roughly ninety-percent increase in light absorption at normal incidence and up to a two-hundred-percent increase at steep angles.
17PubMed Central. Butterfly wing architectures inspire sensor and energy applicationsThe appeal is that these biological nanostructures work across a broad range of wavelengths and angles without needing expensive multi-layer synthetic coatings. Whether the specific nipple arrays found on clearwing moth membranes will be directly replicated in commercial products remains to be seen, but the design principle, a sub-wavelength surface texture that suppresses reflection, has already moved from biology labs into prototype solar cells and optical sensors. For a group of insects that most people either mistake for wasps or curse for destroying their squash plants, clearwing moths have generated a surprisingly wide footprint across ecology, agriculture, and engineering.