Science Illustrated

Let’s Talk About the Awesomenes­s of Bugs

- Anthony Fordham

As our population rockets toward eight billion, it’s tempting to think that humans are the most successful animals on the planet right now. But is that really true? Because the insects number not in the billions, trillions or even quadrillio­ns. Rather, entomologi­sts estimate the current LIVING insect population of Earth at around 10

quintillio­n individual­s. Individual insects are no match for a large animal like a human or indeed anything else. Insects and other arthropods are eaten by their millions every day. Tiny changes in the environmen­t that humans wouldn’t even notice can wipe out entire population­s of billions.

And yet, our ability to deliberate­ly control any given insect population remains basic at best. We’ve had some success eliminatin­g mosquitoes - and thus malaria - from regions where people have enough money to keep up with the spraying. We’ve developed pesticides to protect our crops. And domestic bug sprays and poisons are a billion-dollar industry.

But all these weapons against insects usually turn out hurting us nearly as badly. DDT is a great insecticid­e, but wrecks the environmen­t indiscrimi­nately. Residual pesticides in food crops are beginning to show long term effects on humans. Properly fumigating your house actually drives you into the street.

And still, every few years the sky darkens and great swarms of locusts descend on the fields and eat everything, and once the swarm flies, there’s not much we can do about it. Just look at your own home. Want a house without a single ant in it? You’d better be prepared to spend half your life plugging gaps and spraying. Even then, if you ever stop, the ants will just come back.

Oh there are some species of insect - the larger, more beautiful ones usually - that face extinction as humans continue to radically alter the world. But as a group, as a type of life, insects are just going from strength-to-strength.

Well, except for one very big setback that occurred a long time before humans came along. See, back in the Carbonifer­ous period, about 300 million years ago, the percentage of oxygen in the atmosphere was much higher. Today it’s about 20%, but back then it was 30-35%.

There’s good evidence to suggest this high oxygen level allowed insects to grow much larger than they do today. The most famous fossil is Meganeura, a dragonfly with a 65 centimetre wingspan.

The oxygen-rich air in the Carbonifer­ous may also have been denser than modern air, making it easier for large insects to fly.

Another key aspect of life in the Carbonifer­ous was a lack of large, flying predators such as birds. With nobody keeping the bugs down, it was possible for insects to develop much larger bodies.

Then, oxygen levels began to fall and birds came along. Life for an individual insect got much tougher. Species adapted by shrinking and developing breeding strategies where thousands of young are hatched in hopes a handful will survive. It’s called ”predator satiation” and it still works today - give the birds so many butterflie­s to eat, they simply won’t be able to prevent the next generation from being born.

Arthropods in general and insects in particular are fascinatin­g life forms. Part intricate toy, part clever robot, part work of art, benign species like beetles and cicadas delight children as much as other species destroy livelihood­s in vast swarms.

I have a sneaking suspicion it’s a bug’s world. And we’re just living in it.

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