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January, 2013


by Valerie

Would you provide habitat for mosquitoes to breed? The first response is usually a resounding NO WAY! After all, mosquitoes are one of the primary vectors of insect borne diseases, many people have an allergic reaction to their bites, and, well, we just don't like donating our blood against our will. What if you thought, though, about the Purple Martin mother trying to gather enough insects to raise her hungry brood of cute little nestlings? Suppose there were no more mosquitoes and the baby birds simply starved to death? All those martin nesting boxes would be for naught if there was not enough prey to satisfy their appetites. Of course, martins eat more than just mosquitoes, but I wanted a simple example to show that many of the animals with which we live play more than one role within the ecosystem. Through a series of checks and balances, the average, garden-variety ecosystem manages to sustain numerous species at various levels in the food web. But here is the catch - if it is left alone.

One of the hardest things for us humans to do is to leave things alone. We seem to compulsively alter not just our home, but the habitat surrounding it, as far out as we can manage, and we don't always do so knowingly. Without getting into a whole larger issue, it is pretty obvious that we've been altering the state of the entire world without any forethought as to what that will lead to.

Since most of us are not in a position to influence policy-makers, governments, or huge swaths of the human population, there is not much we as individuals can do about the big picture. However, think smaller - MUCH smaller. Most of us have at least a small plot of land that surrounds our home, whether it is a tiny garden patch or a comfortably ample yard. We share that same land with other creatures, the majority of which are insects. For some folks, it is painfully obvious - bugs are bad so they should all be killed by any means necessary, including the use of toxic chemicals. Considering that 4 out of every 5 species on Earth are insects, this overly simplistic blanket statement is ludicrous. Less than 1% of insects are at odds with human interests. These mostly include carriers of disease, pests of commercial crops and stored foods, and house guests that are encouraged by our living habits. The other 99+% are either beneficial or neutral as far as we're concerned. In fact, without insects, it is questionable whether our species could survive at all.

A Paper Wasp (Polistes exclamans) butchers a caterpillar

Here's a good example of how complicated it can be: paper wasps. These are a genus of social wasps that create the umbrella-shaped nests hanging from eaves of houses. Social wasps kill prey so they can feed the developing young of the queen back at the nest. Although they will attack other insects, the main things on the babies' menu are caterpillars. Since caterpillars are herbivores, and would literally defoliate trees and other vegetation if left completely unchecked, it is important for the health of the ecosystem that their numbers be somehow reduced. Although the wasps do an admirable job at reducing caterpillar numbers, they also can sting and will do so in defense of their nests. For most people, the sting is painful but not a major concern. Some people, though, are allergic to the venom and can actually die from a sting. So, there is not really a clear-cut path here; if nests are too close to human activity or endanger certain inhabitants, they should probably be removed, but it is also possible to leave those that pose no obvious threat. Some people like butterflies in their gardens and wasps kill any kind of caterpillar, whether it is a moth or a butterfly, so that is one more factor to consider. It takes some thoughtful decision making on the human's part, but that is what our big brains are for.

There are all sorts of insects that just don't register on most people's radars because they are not poisonous or pests. They just are. Although we don't notice them, that doesn't mean that they don't interact with, contribute to, or benefit from other aspects in the environment. It would be arrogant to assume that something doesn't matter just because we aren't aware of it.

So, if just a few insects are bad and a few are good and the rest are somewhere in the middle, how can that knowledge let us make better decisions about the small segment of habitat over which we have any influence? We know that biodiversity is a good thing, and the more different species that are present, the more resilient an ecosystem is when faced with unusual circumstances, such as prolonged drought or extremes of temperature. The food web, which includes us too, is far more complex than the old textbook example of plant>insect>bird can convey. As different animal populations react to environmental factors, sometimes fluctuating quite wildly, those species that are interdependent also must react. With more different species available, there are more possible solutions to any shortfall of resources.

If we know just this little bit more about how the habitat around us supports or discourages other species, it is possible to make a few simple choices to allow the wildlife (all animals other than us) a chance to survive as well. Diversity of plants is a big factor in a healthy ecosystem, so allowing a few weeds in the lawn, having less mowed grass and more garden beds with more native than exotic plants, and maybe even permitting an unkempt weedy corner to exist are all helpful. Leaving gardens a little messier, by not removing all the dead growth, allows the natural populations of both predators and prey to balance each other. Many perceived "problems" with pests in gardens will just sort themselves out when dealt with in my favorite way - do nothing.

Another way to live more nicely with our fellow animals on this planet is to change our attitudes and behaviors a little. Not every insect needs to be squished on sight, not even those that look unfamiliar or scary. Plants are not just attractive decorations for our yard, but are the base of the food web, so any plant that is NOT eaten by some animal is not really doing its job. Some animals do take quite a chunk when they snack. Deer and rabbits come to mind. Most insects, on the other hand, have smaller appetites. There may be more of them, but the damage they do usually looks worse than it is. People are easily panicked when they notice that their native plants are nibbled ragged or fail to bloom during any particular year. A friend recently sent me a photo of "locusts completely defoliating all our trees." In the picture were several large grasshoppers on the trunk of a tree that still had LOTS of leaves, with more very luxuriant trees shown nearby. The sight of those numerous insects were blinding her to the reality of the situation. The trees could take it. Considering that the plants and animals in any area have coexisted for a very long time, it is probably safe to assume that nature really can take care of itself. The herbivore population spikes, flower-destroying droughts, and other short-term catastrophes can generally sort themselves out. A nice wet spring, followed by a bumper crop of caterpillars usually means good nesting success for songbirds. You get the idea. Why worry?

Some people get an inkling of this "sharing" idea when it comes to butterfly gardening. It is a little hard to see a favorite Passionflower vine chewed down to nothing, but that is what it takes to raise caterpillars to adulthood. Eventually, one cultivates their garden to have enough for both the hungry mouths and the beauty-seeking eyes of the beholder. I also like to think that there is something inherently good about letting other creatures live without our interference. If they don't directly harm us, and we can tolerate their footprint on the habitat, then there's no reason to get all agitated over a few unfamiliar bugs or the destruction of a few plants. Sometimes all it takes is careful observation to gain some insight into how this marvelous planet can support such an amazing array of life.

Whether we like it or not, we humans have no choice but to share the world with billions of other creatures. It's true that wildlife does not know how to share (only our big brains can fathom such a concept), but it also doesn't take more than it needs to survive.

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