Scientists are investigating the mystery of a bug with one of the coolest names in the animal kingdom: the diabolical ironclad beetle. The diabolical ironclad beetle (Phloeodes diabolicus) lives under the bark of oak and other trees in the western […]
Scientists are investigating the mystery of a bug with one of the coolest names in the animal kingdom: the diabolical ironclad beetle.
The diabolical ironclad beetle (Phloeodes diabolicus) lives under the bark of oak and other trees in the western United States, feasting on fungi growing there.
Like other beetles, it plays dead when in danger. Although this tiny bug isn’t much bigger than a grain of rice, it can ensure crushing forces equivalent to 39,000 times its body weight, the researchers discovered.
That’s about four times more than the strongest humans exert when squeezing the beetle between the thumb and forefinger.
Phloeodes diabolicus has one of the toughest natural exoskeletons scientists have ever seen. According to research published in the journal Nature, the insect’s shield is so durable, few predators have successfully made a meal out of it — and surprisingly it can even survive getting run over by a car.
This is a bug that scientists famously need to drill a hole into before they can stick a pin through it.
A research team from Purdue University and the University of California, Irvine (UCI) have concluded that when an extreme amount of pressure is exerted on the beetle, its “crush-resistant” shell adapts to the situation by stretching, rather than shattering.
Its nearly indestructible shell, coupled with its convincing acting skills when it comes to playing dead, leaves the beetle with few predators.
“The ironclad is a terrestrial beetle, so it’s not lightweight and fast but built more like a little tank,” lead author David Kisailus, a UCI professor of materials science and engineering, said in a news release.
“That’s its adaptation: It can’t fly away, so it just stays put and lets its specially designed armor take the abuse until the predator gives up.”
To study the tiny tanks, a member of the research team, Jesus Rivera, captured beetles and brought them back to the lab. First, researchers discovered the beetle’s exoskeleton could withstand around 150 newtons of force — 39,000 times its body weight. Three other species of terrestrial beetle were only half as resilient.
But what is the reason behind this particular exoskeleton so much stronger? The research team visualized the beetle using a 3D imaging technique called microcomputed tomography, which works as an X-ray for the whole organism. They focused on the ironclad’s elytra.
It may seem unusual for the ironclad to have elytra. After all, it’s a ground-dwelling beetle that can’t fly. But it has evolved from a beetle that, at one time, could, and its elytra are critical to its exoskeleton’s strength. They’ve fused in the most remarkable way creating a winding, twirling suture.
The researchers have described it as pieces of a jigsaw puzzle, connecting. Lock two pieces together and the likely point of failure is at the “neck” of the jigsaw piece. But studying the suture under a high-powered microscope and using computer simulations, the team didn’t see any catastrophic failure.
The suture seemed to hold up, transferring the stress across the entire region, rather than cracking open. That’s important — it protects the beetle’s neck
Moreover, the chemical composition of the ironclad’s elytra is slightly different from that of a flying beetle. It appears to have a higher concentration of protein mixed in, which could increase the insect’s toughness.
The researchers conducted extensive research and explored how this exoskeleton geometry might enable the development of tougher materials.
They took the lessons learned from the beetle’s suture and created some carbon fiber jigsaw pieces to test the mechanical strength in a real-world application — fasteners used in aerospace engineering. The jigsaw pieces that mimicked the ironclad performed the best.
“This work shows that we may be able to shift from using strong, brittle materials to ones that can be both strong and tough by dissipating energy as they break,” said Pablo Zavattieri, a civil engineer at Purdue University and co-author of the study.
Scientists are now using the beetle’s design to build similarly strong fasteners with potential for use in cars, bicycles, and even airplanes. Who knows, one day you might see a Volkswagen Beetle as tough as a, well, beetle.