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Thursday, April 19, 2001

WILD WATCH

KEEP ON ROLLING

Up to your ears in, um, you know, uh...


First of two parts

About 18 months ago, someone who knew that I was a naturalist asked me, in all seriousness, why we humans shouldn't just eradicate all insects and similar creepy-crawlies.

Her rationale was that because she and her friends didn't like the nasty critters, then they would be better off without them. So wouldn't everyone else be better off without them, too?

The navete of the question stunned me so much that I was unable to respond immediately. Could anyone really believe that we would all be better off without insects? Could anyone actually believe that we could even survive without insects?

We may occasionally attract the unpleasant and unwanted attentions of a mosquito, a wasp or a fly, but we should not hate all of the millions of species of insects in the world based on a poor understanding of just a handful of species.

Have we got a lot to thank insects for! If we did something as daft as to attempt to eradicate them all, we would quickly find out that much of our food comes from or depends on flowering plants: With no insects to pollinate them, we would not last long at all.

Furthermore, without insects clearing up after us we'd soon be eye-deep in ordure. Think of all the mammals in the world: the hordes of people living in rural areas, the herds of domesticated animals, the thousands of millions of sheep, goats, pigs, cattle, etc. roaming pastures around the world. Consider what they do all day: They eat, and they, well, to put it scientifically, they defecate.

Have you ever wondered where the millions of tons of biowaste that is deposited daily actually goes? Why aren't the pastures of Africa, the Americas and Europe all neck-deep in excrement?

On a sandy track in the Namibian desert I came across one of the hardworking creatures that we depend on so much: a scarab beetle struggling with a ball of dung the size of a grape.

There are innumerable species of these beetles occurring around the world and they range in size from just 5 mm to the enormous 12-cm-long African goliath beetle, one of the heaviest insects in the world. If we were to enshrine insects in a Hall of Fame or to give out Oscars for our hardworking support cast, then scarab beetles deserve both accolades.

Among their enormous throng are many species that feed on manure, others that eat decomposing plant material (and you can hardly begin to imagine how much of that there is in the world), other species that eat leaves and some that find fungi to their taste. A handful of species can be considered to be agricultural pests, but global agriculture couldn't survive at all without the rest of them.

The ancient Egyptians knew a thing or two about scarab beetles. They considered them to be sacred, depicting them in wall art and jewelry, in part because of their beautifully colored wing-cases, but also because they valued their services. The ancient Egyptians looked on the daily path of the sun rolling across the heavens and saw a link there with the beetles that rolled balls of dung along the ground, and so they represented their most important god, the sun god, as a scarab. They certainly had an interesting perspective on life!

The scarab beetle comes in various guises -- it is sometimes known as a dung chafer or tumblebug -- and follows various lifestyles, but the scarab or dung beetle's most spectacular role is as an animated pooper-scooper. They home in on freshly deposited dung and, using their special paddle-shaped antennae and scooplike head, form neat balls of manure and roll them away.

They are not the only creatures attracted to dung. In southern Africa, I watched as an elephant wandered through the open savanna of Botswana's Okavango Delta. Suddenly it dropped a massive pile of steaming dung, and within moments, perhaps before it even landed on the ground, the local army of beetles was at action stations. By the time we inspected the dung the first flies and beetles were already staking their claims to it.

As luck would have it, I passed the same way 24 hours later. I was astounded to find that the huge dung heap had already been reduced from roughly soccer-ball size and shape to a flat pancake. The pancake was pockmarked with small craters where the beetles had cut out their booty and where a succession of beetles, flies and other insects had made their inroads. The surface was already dry, and whatever flies had laid their eggs in the dung had no doubt already lost out to the beetles.

I counted more than half a dozen different species in attendance. Natural recyclers all of them, rushing to take advantage of the temporary richness available to them.

What the dung beetles do with the bounteous dung is rather neat -- dicing it, rolling it away and burying it is just the first part. During certain parts of the year, the beetles bury themselves along with the dung ball, which they feed off. At other seasons, females lay their eggs in balls of dung; the larvae feed on the dung, hollowing out the inside of the brood ball as they grow. Then they pupate, and when development is complete they wait for just the right amount of humidity before emerging as new adults.

The one type of dung beetle that I would love to see most is the giant dung beetle (Heliocopris andersoni) of southern and eastern Africa. This monster of a beetle rolls dung balls as big as 10 cm in diameter and coats them with clay before burying them.

Write to markbrazil@compuserve.com or via snail-mail care of The Japan Times.


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