There are many geniuses of camouflage in nature. The same goes for hoverflies. They disguise themselves as wasps to avoid predators like birds, spiders, and praying mantises. However, some hoverflies closely resemble wasps but do not mimic accurately. Why don't they mimic perfectly if it is to disguise themselves? The answer lies in efficiency.
A research team led by Professor Christopher Taylor at the University of Nottingham announced on the 3rd in the international journal Nature that "the ability to distinguish between hoverflies and wasps varies depending on the predator, demonstrated through experiments with life-sized models." Sharp-eyed predators should resemble wasps closely, but sluggish predators can get away with a rough imitation.
◇Great tits have sharper eyes than spiders
Hoverflies belong to the order Diptera, but they feed on nectar and pollen like honeybees, which are in the order Hymenoptera. They disguise themselves as wasps, which have stingers, to protect themselves. Depending on the species, their appearance can be so similar to wasps that it becomes difficult to distinguish between them, while some may be closer to flies.
The research team at the University of Nottingham used a 3D printer to create life-sized hoverfly models and conducted experiments with various predators. They produced hoverflies with varying degrees of similarity to wasps, just like in nature.
First, they provided great tits with a container containing brown click beetle larvae for experimentation. A hoverfly model was placed on top of the container. The great tit avoided the container with the model resembling a wasp but freely approached the others. This indicates the bird's ability to distinguish subtle differences between wasps and hoverflies. The birds first evaluated color. Size was also crucial. The shape and pattern were of lesser importance in identification.
Hoverflies are a typical example of Batesian mimicry. This phenomenon involves disguising oneself as an unpalatable or harmful species for protection, named after the British naturalist Henry Walter Bates (1825–1892) who studied butterflies in the Brazilian rainforest. Caterpillars of the hawk moth inflate their heads and necks in front of predators to mimic the head of a venomous snake and even make hissing sounds like a snake.
The Nottingham research team also noted that the ability to distinguish between hoverflies and wasps varies by predator. Unlike birds, invertebrate predators like spiders or mantises didn't differentiate well even without much imitation. The researchers suggested that the difference in the predator's identification ability could explain why inaccurate Batesian mimicry persists in nature. This means that in the eyes of less perceptive predators, a rough imitation suffices.
◇The degree of imitation varies by predator
According to Darwin's theory of natural selection, only the best survive in any field. There shouldn't be any clumsy mimics. However, there are hoverflies that imperfectly imitate wasps. Scientists have proposed various theories to solve this puzzle, which Darwin's theory does not explain. They argue that what appears to be clumsy mimicry is actually the result of imitating several features that predators dislike.
The Nottingham research team revealed that the degree of mimicry varied with the predator. Although it may appear clumsy to human eyes, it could look different to the predators. Earlier, Professor Thomas Sherratt from Carleton University also published similar research results in an article in Nature in 2012.
In an analysis of 18 species of hoverflies, the Carleton University research team found that the larger the body size, the more perfect the mimicry became. Larger hoverflies hold greater value as prey, prompting birds to check them multiple times. Even if there is a risk of being discovered as a real wasp and being stung, they take the chance. For larger hoverflies, which sharp-eyed birds target, the effort invested in mimicking wasps is inevitable.
According to the Nottingham experiment, unlike birds, invertebrate predators like spiders or mantises did not differentiate well even with less imitation. This means that they are not less similar to wasps; rather, in front of less perceptive predators, they settle for a rough imitation.
Professor Sherratt agreed with the Nottingham team's claims in a commentary paper in Nature this time. He noted that this study particularly demonstrated how 3D printing can aid research in fundamental questions of evolution.
References
Nature (2025), DOI: https://doi.org/10.1038/s41586-025-09216-3
Nature (2025), DOI: https://doi.org/10.1038/d41586-025-01766-w
Nature (2012), DOI: https://doi.org/10.1038/nature10961