The Gordon Gnohm

Be sure to read my article, Future Farmer in The Braidwood Bugle every Wednesday. 

What The Fact?? BESS BEETLES

Bess beetles live the good life: lots of family, good conversation, and poo. Lots and lots of poo. 

Living Conditions

Bess beetles are unusual in that they live in a colony made up of several generations of a family.

They eat decomposing wood and live within rotting logs in a complex of tunnels. Adult males and

females excavate their tunnels, defend the colony and care for the young. You can tell when a log

has Bess Beetles because it will often have a pile of sawdust at the tunnel entrance.

Say What?

Have you ever heard a log making kissing sounds?

That was probably Bess Beetles, which are very good communicators. They can make 14 unique

sounds by rubbing parts of their bodies together, which can be heard from outside the log. To us,

most of their conversation sounds like a kid making fun of people kissing, but it means that these

beetles have one of the most complex communication systems in arthropods. This probably evolved

as a way to negotiate with their colony mates, as well as to scare off predators when moving

between logs. What bird wants to eat something making smooching noises?

Eww Poo!

That brings us to the poo. You see, wood is hard to eat, because it is literally hard, and because it is

tough to digest. So when baby Bess Beetles hatch, mum and dad chew up the wood for them, but

pre-chewed wood isn’t very nutritious, so they need to eat their parent’s poo too. Bess Beetles have

a variety of microbes living in their gut which help to break down wood fibres, and they continue to

break it down once it has been pooped out. This means that the poo is actually far more nutritious

than the wood! 

They use their poo to line their tunnels, and even build a cosy little cocoon for the

juveniles to pupate in out of poo. They quite literally live in a world of poo!

It is rare to find beetles living in family groups as Bess Beetles do, referred to as subsociality. This

lifestyle may have evolved due to the need to pass microbial endosymbionts from parents to

offspring in order to digest decomposing wood.

Community Benefits

Bess beetles are members of the saproxylic community. No, that isn’t a new online thing, it is the

name for all the weird and wonderful creatures that live in rotting wood. Together, they do the

important work of turning fallen trees into soil for a new generation of trees to grow in, and

returning carbon to the soil. 

So rotting wood isn’t being wasted, it is just slowly being recycled.

Saproxylic invertebrates are a strange bunch, let’s just say they don’t get out much. It can take over

a hundred years for a log to decompose, so creatures may only need to move every hundred or so

generations. When they do move between logs, they are vulnerable to dehydration and predation,

so they try to find the closest available log. All of this means that they have high rates of endemism,

which is where the beetles in your backyard are only found in your valley, and the beetles in the next

valley are a completely different species. So look after your locals, they could well be new species as

yet unknown to science!

Unsung Heroes

When people think about beneficial invertebrates in the garden, they tend to focus on the predators

such as lady beetles, or the pollinators like bees. However, the detritivores are really the unsung

heroes of the recycling in your garden. Without the clean-up crew, we would all be neck deep in dead plants, and soil would be nothing more than rock dust. 

So who are they, what do they do, and how can we encourage them to

be part of our garden ecosystem?

The bulk of the work of breaking down dead plants is done in the soil by bacteria, fungi, and

actinomycetes. One square metre of garden soil can contain 10 trillion individuals, and they give

good soil that beautiful aroma of life. Nematodes, springtails, earwigs, slaters, beetles, flies, and

earthworms get involved by eating all sorts of dead plant and animal matter. These creatures then

get eaten by others, and so on, allowing energy and nutrients to circulate through the food web.

Waste from all these creatures carries vital nutrients such as carbon, which is sequestered in the soil

rather than causing trouble in our atmosphere. This builds nutrient dense and biologically active soil

that your plants will love you for! Being rather large ourselves, it is easy for us to forget the

detritivores because most of them are tiny, hidden below ground or in logs, and they are often

nocturnal. However, take a close look next time you are turning a compost heap, it should be

heaving with them!

Ready to Pounce

Encouraging detritivores to live in your garden is easy, just don’t take their food away! By leaving

some dead plants around, providing mulch, and including untreated wood in your landscaping, you

are creating habitat that can sustain a community of detritivores.

Then, when there is a big job to do, such as in autumn if you have deciduous trees, you have a clean-up crew there

ready to spring into action! Just remember to take some sensible precautions around fire and termite risk. So next

time you feel a bit grumpy about your mulch disappearing, just remember that there is a whole community of

creatures working for you to build your soil, and their pay is as cheap as (wood) chips!  

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