Age of beetles

I'm still sitting on that high black willow limb I told you about last week. (And wouldn't that be wonderful in weather like this? The temperature today is 30ºC (86ºF) with Ontario's typical summer humidity. Wouldn't it be nice just to sit in the top of a tree for a week, looking down at the lazy stream, with a bottomless glass of iced tea?)

But back to my point. I've already noticed the water striders, gnats and big black ants. Then an iridescent bauble the size of a sequin lands and goes for a spring jaunt through the hair on my leg. It is a jewel beetle. An arm's length away, I notice a ladybug clambering on a fresh shoot sprouting from the willow limb, probably catching aphids attracted to the fresh growth. A darker creature the size of a pin head alights on the back of my hand. It too is a beetle, too small to see clearly, but it appears to have the snout of a weevil.

Here I am somewhere on the Earth, suspended 10 metres above the ground, and the space around me is teeming with different species of beetles. I already claimed this is not the Age of Man, but the Age of Insects. Now I will go further and say it is the Age of Beetles.

Scientists have described about 300,000 species of beetle, or 40 per cent of all insects. That means that almost one in five of Earth's animal species is a beetle.

And they might not seem as numerous as the teeming hills of ants or swarms of mosquitoes, but, according to David Rockwell in The Nature of North America, an ordinary acre of temperate meadow supports 18 million individual beetles.

Obviously they are one of nature's most successful designs. Like most insects they have two pairs of wings, but the front pair is modified into a protective sheath, the elytra, which cover the membranous hindwings and soft abdomen. A beetle is literally a miniature, live tank. But they are extremely diverse. In fact the bioluminescent firefly is actually a beetle.

A few beetles are economically harmful, such as the boll weevil, whose larvae infest cotton crops, the plum curculio, a pest of fruit trees, and bark beetles, whose larvae can destroy trees important in forestry, and which spread the fungus which causes Dutch elm disease.

But beetles are much more significant for their beneficial species. Ladybugs are well known for their appetite for aphids and scale insects. Carabid beetles feed on harmful caterpillars such as the gypsy moth larva and spruce budworm. Firefly larvae feed on slugs and snails, and important pest of vegetable crops.

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