Meet the Bess Beetle
Real Singing Beetles
Have you ever been digging in the garden or your flower bed and come across a HUGE grub or large black beetle? If you've ever spent any time digging around outside or under logs in the Eastern US (or Midwest) then you've probably encountered our guest beetle for today, the Bess beetle or Bess bug . Their Latin name is Odontotaenius disjunctus (O-don-tote-a-knee-us dis-junk-tus). Odon means "tooth" and taeni means "band" or "ribbon". This refers to the bands of teeth on their bodies (abdomen and wings) that they use to make sound. Dis refers to "separate", "double" or "two", and junc refers to a "rush" or "reed". This may reference that they sound like rushes or reeds rubbed together.
Bess beetles are one of the largest beetles you can find (1.2-1.6" long) and can be quite startling. Their backs look like shiny patent-leather dress shoes with legs (there's an image for you). Their bellies have golden hairs and their head has a single horn. Bess beetles are in the scarab super-family (Scarabaeoidea), and there are over 500 species around the world. The Bess beetles of North America (Odontotaenius disjunctus) are one of the few scarabs in the US. Look carefully and you can see the characteristic scarab looking club-like antennae on their head.
The common Bess beetle name probably comes from the the early English term buss meaning "kiss" or the French term baiser or even une bise, which also means "to kiss." Both sound very close to "Bess." This name may attributed to the noise that the beetles make when they're startled or feel threatened. It's akin to a "kissy-sound," like what you'd make when making fun of your older brother kissing his girlfriend or the practice smooches you did as a kid in the mirror. The sound is made much like how a cricket makes sound, by rubbing body segments together, a process called stridulation (st-rid-you-lay-shun). Listen to this...
Click here for an audio file from the University of Florida Entomology Department and more kissy beetle sounds.
Adult Bess beetles and their grubs can both make sounds. The grubs even have reduced third limbs which can rub against their bodies and stridulate (take a look next time you run across one in the garden). Amazingly, Bess beetles can make up to 17 different sounds! This is considered one of the most complex sound and communication systems in arthropods (animals with exoskeletons, like crabs, lobsters, beetles, crickets, etc).
One reason for the Bess beetle's vocabulary isn't just for platinum and gold records, it is because they are one of the few social beetles (long hair not withstanding). As adults and grubs, they live in rotting wood (most usually hardwoods like oak) with other Bess beetles. Their communication system is thought to help them navigate living in these colonies and competing for the optimal spaces to lay their eggs and larvae. Additionally, it's been shown that when the beetle is outside of a log the stridulation sounds serve as a defensive mechanism. How did they figure this out? Some poor graduate student got to remove the rough bumpy bits from the beetles, the parts that make sound, and then presented hungry crows with a set of beetles that could make sounds and those that couldn't. Those that could make sounds startled the crows and had a better chance of surviving; crazy eh? This was a real thing, you can read the paper by clicking here.
What the Frass?
Living in hardwood is "hard", and the Bess beetles have to chew their way through logs, and in the process helping the rotting logs to decompose. However, they're pretty particular about the rotting logs they choose, and they need specific humidity to keep their grubs and adults from drying out. They also like logs that have specific microflora (bacteria and fungi) that have already started breaking down the hardwood. This helps them get a jump start on their fibery diet. Interestingly, when they eat the wood they poop out dry powdery stuff called "frass" . (Super for when you're ticked off at your kids. . . "WHAT THE FRASS!!!!") The frass is a favorite for other bacteria and fungus that like to decompose wood, so it's a win-win for everyone when the beetles poop. The fungi start growing on the frass and the frass helps break down wood for the beetles. All of this picky wood eating, humidity needs, and frass-fungi specificity is why you often find Bess beetles living together. It's hard to find the right housing with just the perfect lawn and frass-poop-fungi.
Regardless of your feelings about big beetles and bugs, it's good to know that there are beetles out there rocking the rotting log scene. Bess beetles are good neighbors that help in the succession of the forest, singing their way (or kissy-sounding their way) through the forest. Next time you see one, look and listen closely for what they have to say and where they're going. They are North America's vocal scarabs, and the next time you make kissey-face sounds you can think of them!