Invertebrates
Diabolical Ironclad Beetle
Nosoderma diabolicum · also called ironclad beetle
The diabolical ironclad beetle is a small, drab, bark-coloured insect from the American Southwest, and it is one of the toughest animals for its size on the planet. You can step on it, and often you can drive over it, and it will simply walk away.
Overview
Nosoderma diabolicum lives under the bark of dead trees in the oak and mixed woodland of the southwestern US and Mexico, feeding slowly on fungi. It is flightless, its wing cases fused into a solid dome, and it can live seven or eight years, very long for a beetle.
Built like a crumple zone
Tests measured the force needed to crush it at about 150 newtons — roughly 39,000 times its body weight. The two wing cases are joined down the middle by a seam shaped like interlocking jigsaw pieces, which under load peels apart layer by layer instead of snapping, absorbing the energy.
A design lesson
A 2020 study in Nature copied the beetle’s crush-resistant joint to build tougher fasteners for aircraft and machinery.
Status
Not Evaluated and not at risk, but slow, flightless, and tied to dead wood, so it depends on mature woodland with standing and fallen timber.
Diabolical Ironclad Beetle: common questions
Can you really run over a diabolical ironclad beetle with a car and not kill it?
Often, yes, if the ground underneath is firm. Researchers who tested the beetle found it could withstand a compressive force of around 150 newtons before its body failed, which is roughly 39,000 times the insect's own weight and far beyond what other beetles of similar size can take. A car tyre rolling over a beetle pressed against hard asphalt or rock applies a large force, but the beetle's armour spreads and absorbs it rather than cracking, so the animal frequently walks away. On soft ground it does even better, because the beetle simply presses into the surface.
What makes its shell so strong?
Two things working together. First, the material itself is a layered composite of protein and chitin arranged so that a crack has to travel a long, winding path to get through, which uses up energy. Second, and more importantly, the beetle has no need to open its wing cases for flight, so evolution has fused them into a single rigid dome, and the seam where the two halves meet down the middle is built like interlocking jigsaw pieces. Under a crushing load that joint gives way gradually, one thin layer peeling from the next, so the structure bends and delaminates instead of shattering. Engineers describe it as a natural version of a graceful failure.
Why is it called diabolical?
The name diabolicum simply means devilish, and it refers to the beetle's rugged, blackish, bumpy, almost sinister appearance rather than to any dangerous behaviour. The beetle is entirely harmless; it does not bite in any meaningful way, has no venom or defensive spray, and its whole strategy is to be inedible by being both impossible to crush and easy to overlook. Early naturalists were also probably reacting to how frustrating it is to pin one for a collection, since an ordinary insect pin will not go through the armour.
Has the beetle actually been used in engineering?
Yes. The 2020 research team that measured its strength went on to model the interlocking suture between its wing cases and to fabricate metal-and-composite fasteners based on the same geometry. Those bio-inspired joints held together better and failed more gently than a standard engineering fastener of the same size, which matters in aircraft and machinery where a connection between two different materials is often a weak point. It is a well-known recent example of learning a design lesson from an insect.