You know, if I were an aphid or an ant, or even a cockroach, I’d be pretty annoyed. Over the summer, as usual, mosquitoes got all the press. They were even featured in Jurassic Park. When was the last time you saw an aphid in the movies?
In an effort to redress this injustice, I offer the following tribute:
Anyone who has driven a long distance cross-country in August knows there are a lot of bugs out there. Scientists estimate that they’ve described about 750,000 different species of insects, and the actual number is estimated to be more like three million (which tallies with my own rough estimate, based on what I’ve scraped off my windshield). Furthermore, fossils indicate insects have been around for 390 million years, and even then were already very similar to species still common today, such as the silverfish.
Insects have three body divisions, called the head, thorax and abdomen, and six legs, attached to the thorax. Many have wings. All have an external skeleton, or exoskeleton.
Insects are cold blooded, with pulse rates ranging from 140 beats per minute in active insects to only one per hour in chilled insects. They don’t breathe through their noses (probably because they don’t have them): they take in air through a series of holes called spiracles along the thorax and abdomen. And they smell with sensors usually found on their antennae, among their mouthparts, or on their feet (so I guess you could say that their feet smell Ñ were you inclined to).
Most insects develop from egg to adult through a complete metamorphosis, passing through a series of stages that don’t even look like one another. The butterfly is the best example, going from egg to caterpillar to cocoon to gloriously coloured winged adult. Some species, like grasshoppers, go through an incomplete metamorphosis, in which each stage looks similar.
Some insects live in complex societies in which specific insects have specific tasks, so that the society as a whole works as a unit, even thought it’s made up of many individuals. Ants, termites and bees are the best examples.
Insects eat many different things in many different ways. Butterflies suck nectar from flowers through a long proboscis they keep coiled when not in use: honeybees, on the other hand, lap nectar with their tongues. Bumblebees can both lap and bite, which enables them to chew their way into flowers to reach the nectar.
Beetles, wasps and ants also have powerful bites (some beetles can chew through soft metals). Some carnivorous insects, like the praying mantis, catch and chew their pray; wasps, on the other hand, paralyze their prey with poisonous stings and lay their eggs in the victim’s still-living body. Termites eat wood: protozoa in their digestive tracts pre-digest the wood’s cellulose, which would otherwise be as unpalatable for them as for us.
The wide variety of insect appetites is what mostly brings them into contact with us, the self-styled dominant species of the planet (though considering the numbers, insects could dispute that claim). Grasshoppers proliferate across the prairies, destroying crops; a tiny brown beetle called the boll weevil destroys millions of dollars worth of cotton every year in the U.S; gypsy moths defoliate orchards and forests; fire ants eat the insulation off of electrical cables; moth larvae eat cloth, and mosquitoes, of course, suck blood. Insects also carry a jolly list of diseases that includes sleeping sickness, bubonic plague, malaria, typhoid fever, dysentery and cholera. No wonder, then, that a lot of the research into insects is aimed not only at understanding them, but at controlling them.
On the plus side, bees pollinate plants and make honey, silkworms provide the fibers for silk, and here in Saskatchewan we’re even using beetles to control leafy spurge.
Both our problems with insects and the uses we’ve found for them arise from the characteristics that make them such a wildly successful form of life. An insect generation generally lasts less than a year, and sometimes only a few days. This allows them to respond quickly, genetically speaking, to changes in the environment (hence the pesticide-resistant insects plaguing our crops). As well, insects are small and many can fly, which means they disperse widely, allowing them to colonize every conceivable habitat (only the polar ice caps are free of them) and learn to eat just about anything.
Their numbers are a tribute to the fact that once a new species of insect evolves, it has staying power. Animal species tend to only last a million years or two. Insects, such as the silverfish in your kitchen and the famous mosquitoes of Jurassic Park, tend to stick around, pretty much unchanged, for a lot, lot longer.
So the next time a mosquito alights on your arm, take a moment to admire it as a representative of a fascinating, endlessly varied life form that enriches the Earth.
Then splatter the little bloodsucker from here to eternity. After all, there are millions more where he came from.
