Bugs bug us

Staff Writer
Tri-County Times

With the possible exception of “cute as a bug,” there aren’t many positive references in the English language to that huge group of creepy, crawly creatures including spiders, centipedes, millipedes and insects collectively referred to as bugs. Almost all except for a few butterflies and maybe damselflies or dragonflies are seen primarily as pests, and something that the world might be better off without. Whole sections of stores have shelves full of products to help us repel and outright kill them. Even though most of those products are purchased to fight a specific insect pest or two, few, if any, are selective enough to attack only the target pests. Most will kill not only the target pest, but any insect that comes in contact with it. Nor does the product have to kill a bug outright to have a profound effect. Less-than-lethal doses of pesticide, even in incredibly tiny amounts, can still leave bugs less able to reproduce; a condition that’s nearly as good as dead. DDT didn’t kill eagles and peregrine falcons outright, but caused their egg shells to thin to the point that they’d break before they hatched. A bird that can’t reproduce is nearly as good as dead, too. Even people who know how important bugs are often claim that cold season outings are better because there are no bugs. It’s just plain tough to like something that bugs us so much.

Insects and arachnids (spiders and mites), are by far the most numerous terrestrial life forms. They are said to be the most successful life forms in the history of life on earth, based on total biomass and numbers of species that are present. Ants, alone, are said to far outweigh all the humans on Earth, but humans spend lots of money to keep them out of our homes and even our yards. What good are they, you ask? Well, you might want to consider how important soil is here in Iowa and around the world. Indians cultivated some pretty large garden and corn plots near their villages, but most of Iowa was considered uncultivated at the time of European settlement, beginning less than 200 years ago. Early pioneers and even more modern folks failed to consider that ants had been “tilling” our soil, one grain at a time, for the 1,000s of years since the glaciers retreated. At the same time they brought grains of subsoil to the surface, they took organic material deep underground to feed their colonies. Their tunnels provided paths for air and water to enter the soil they were helping to fertilize and create. Earth worms couldn’t have done all that work alone. Most of our soil wouldn’t be here without those thousands of years of ant tillage.

A recent study of chimney swift colonies in old chimneys was able to document how their diet changed over the years. Swifts eat only flying insects. The hard indigestible parts of their bodies accumulate in each year’s layer of droppings at the bottom of the chimney. Biologists can identify what the swifts were eating each year by studying those old insect remains. The story that’s told in that study should be a wake-up call for us. The percentage of larger-bodied beetles and other larger insects had steadily dropped over the years, meaning that the swifts were having to feed on smaller insects that provide less nutrition per catch than the larger ones that were once dominant in their diet. The fact that swifts leave their droppings in the same place year after year allowed a good analysis of their diet over time. Other birds scatter their droppings over wide areas. Although we can’t document their diets by examining their droppings, we know that most birds feed primarily on insects, at least while they’re young. If a whole class of insects like beetles are in decline, then many species of birds may be having similar difficulties getting enough nutrition. Even birds like doves that eat only seeds, even when they’re young, still depend on insects. Seeds can form only when flowers are pollinated, and that brings us right back to insects. It would be accurate to say that without bugs, most birds would disappear.

They may bug us, but without bugs, even people wouldn’t survive for long because we depend on them to pollinate many of the plants we eat. You say that we don’t eat carrot or broccoli seeds, so why do they need to be pollinated? Well, most of our food plants are annuals or biennials. Somebody has to let them grow until they flower and get pollinated in order to produce enough seed to grow food plants we harvest to eat. If critical classes of bugs are truly in decline for whatever cause, be it climate change or insecticide use, then we’d better find some ways to reverse that trend. Life on Earth may depend on it.