by Coggin Heeringa, Director, Crossroads at Big Creek; Vice President, Wild Ones of the Door Peninsula
Things certainly are lush and green this summer, and most trees look really healthy. Of course, if you look closely, you’ll see that some tree leaves are riddled with holes while others are still in perfect condition. Insect-resistant trees are really great – unless you like birds.
If you like having birds around, there is nothing worse than insect-resistant trees. Usually the shrubs and trees that are marketed as insect-resistant are exotic or alien species. An increasing number of the plants used for landscaping are from some other part of the world. Our native insects do not recognize alien plants, and in many cases, they are unable to digest their leaves.
That’s one reason why the members of Wild Ones of the Door Peninsula are so enthusiastic about native plants: They form the foundation of almost every food web.
By this time of year, the leaves of native trees are usually peppered with holes or have chewed margins. Some leaves are merely lace-like vein skeletons because insects have eaten the juicy, green tissue.
But unless you look carefully, you probably will not notice insect damage on trees and shrubs. Birds do. That’s what they look for. Most insects are either tiny or well camouflaged and very hard to see, so birds search for leaf damage to locate their prey.
What kind of birds eat the little caterpillars and other insects in trees? Almost all of them. During breeding season, when our songbirds are feeding themselves plus their offspring, they need protein, and the world’s best source of protein is insects. Researchers tell us that pound for pound, insects provide more protein than beef.
In our area, songbirds – even those we think of as seed-eaters – feed themselves and their young with protein-rich caterpillars.
So the trick is to attract moths and butterflies to your yard. It’s remarkably easy. All you need to do is plant native flowers, trees and shrubs, and native insects will lay eggs in native plants.
If your landscape is made of alien plants – those from another part of the world – it is unlikely that you will host birds in the summer. Many researchers now believe that the decline in birdlife in urban areas is due to the proliferation of non-native landscapes.
Curiously, insect damage on leaves attracts the very birds that keep those insect populations in check. If your yard is filled with native plants, insects will not get out of hand because birds will eat them or feed them to their offspring. And there is a very good chance that soon after, parent birds will take their young to your feeders.