In Praise of Bugs

A yellow swallowtail butterfly visits a purple Buddleja ‘Lochinch’ in our Palo Alto garden.

Most homeowners, if they think about insects in their landscape at all, think of them as pests to be controlled: overflowing ant colonies, aggressive wasps, caterpillars that eat their precious plants.

But the fact is, each of these species—and literally thousands more—are indispensable to life as we know it. They pollinate the crops we harvest, aerate the soil so plants can thrive, even prevent more harmful species from overpopulating.

So why do bugs… bug us?

One (very good) reason is that many insects actually can harm us. Mosquitoes and ticks can spread debilitating diseases; spiders and centipedes can poison us; and even non-venomous insects like wasps and bees can give us a painful sting (which can provoke a life-threatening immune response in some people). In the face of these real dangers, fear is a perfectly appropriate response.

Insects also invoke an emotional response that scientists believe may be uniquely human: disgust. We’re averse to insects like flies and cockroaches not because we fear they will harm us, but because we associate them with rotting food containing microorganisms that could. Similarly, insects that “invade” our homes disrupt the clean, comfortable environment we have worked hard to create.

Another reason we’re so bothered by insects is that they are so very different from us. They are some of the smallest creatures we can see. They either have no skeletal structure at all, or their skeletons are on the outside. They have weird eyes, and too many legs. They often make fast, jerky, unpredictable movements, whether in the air or over ground (or skin). Even their communal social structures are unnerving to us: everyone knows there’s no such thing as “a few” ants. To “stir up a hornet’s nest” is to invoke a world of hurt.

And yet, bugs—even those we find threatening or disgusting—on balance do far more good than harm in the landscape.

Ant tunnels convey the oxygen and water that plants need to grow and reproduce. Wasps help break down dead plant and animal matter, hastening the return of those nutrients to the soil. Caterpillars are the staple diet of baby birds, who grow up to eat seeds they then disperse to make more plants. (Caterpillars also transform into butterflies and moths who pollinate the flowers that make food… and more plants.) And no one has ever said a disparaging word about a ladybug—except maybe the aphids they eat en masse.

Fig-eater beetle (Cotinis mutabilis) on Euphorbia plant in an Encinitas back yard.

There’s also value in the fact that bugs are, generally speaking, beautiful. Few people would dispute that butterflies are truly “jewels on the wing” that bring delight and awe wherever they float. But so many other insects are equally wondrous, if we can check our fear and disgust and resist the urge to flail around like we’re swatting at a swarm of pint-sized piñatas. Have you ever allowed yourself to notice the fur on a buzzy bumblebee? The iridescent exoskeleton of a boisterous fig-eater beetle? The intricate markings on everyone’s favorite enemy, the yellowjacket?

This isn’t to say we should pause our efforts to eradicate malaria-bearing mosquitoes, or allow said yellowjacket to invade our backyard dinner. We are, after all, human.

Which means we’re intelligent enough to distinguish between the bugs that truly pose a threat to us and the ones we truly can’t live without.

Caterpillars, for instance, are essential food for amphibians, small mammals, bats, and many birds—the foundations of our food chain, who pollinate our crops and, incidentally, eat lots of “bad bugs” like mosquitoes. Verdance’s landscape designs now intentionally include “keystone” plant species whose very purpose is to be eaten by caterpillars, to support the larger cycle of life. It’s really the least we can do.

There’s very little harm, and lots of benefits, to learning the role of insects in our environment and stopping our use of chemical pesticides and other inappropriate controls. Ants, caterpillars, bees and (most) wasps and spiders have exactly zero interest in us or anyone else who isn’t a plant or a smaller insect. It’s high time we let them go about their busyness, and simply enjoy the fruits of their labors.