Native Plants, Insects, and Us

In many regions of the world, nature is out of control. That is, plants are growing fast and furious in areas where they did not evolve, a process that began over 450 million years ago. Over time, plants developed a complex relationship with other living things, cooperating to give and take. Exchanges of gas, webs of food, and adaptations to change continued once the first members of the human family appeared 6 to 7 million years ago and slowly, slowly evolved when the first human appeared a mere 150,000 years ago.

The planet Earth is a very large place with a wide variety of climates and altitudes. Plants that have evolved in place for millions of years do not alter themselves quickly. Therefore, there is no reason to believe that in the mere 500 or so years since man has been moving plants and animals from place to place on the globe that evolution would magically speed up. Air travel has become commonplace and the exchange is happening faster. Mankind has been altering nature much faster than it can evolve.

Native Plants Moved From Places Where They Evolved

When native plants are moved, they may not grow if they do not attract a pollinator. However, if they do begin to grow in an area where they have not evolved to be part of the natural give and take, they may grow and thrive when close substitutes let them play. Many people like these plants because they are ‚”pest-free.” In other words, non-native plants may not be useful as a host for native insects or tasty as food for animals. However, if there aren’t as many insects, there will be fewer butterflies and birds. Here’s where things begin to get out of balance.

And it gets worse. Unfortunately, some of these non-native plants grow a lot. In fact, they may take over the area and out-compete native plants. With the loss of native plants, there will be even fewer insects and the food web unravels.

Native Plants and Native Insects

According to Douglas W. Tallamy in his book Bringing Nature Home: How Native Plants Sustain Wildlife in Our Gardens, we should be gardening to ensure insect diversity. He says that of the 9 million or so insect species, only 1 percent effect humans in negative ways. The other 99 percent ‚”pollinate plants, return the nutrients tied up in dead plants and animals to the soil, keep populations of insect herbivores in check, aerate and enrich the soil, and … provide food either directly or indirectly for most other animals.” That includes us.

Selecting Plants for Landscapes

When selecting plants, Tallamy urges readers to select plants that support the most insects. With many different types of insects in the garden or lawn, they will keep each other from becoming a nuisance. It’s an eat and be eaten world out there! A diverse habitat is a lively and balanced habitat.

He suggests the following trees for the U.S. eastern deciduous forest biome (New York, New Jersey, Connecticut, Rhode Island, Maryland, Delaware, Pennsylvania, and Virginia), in descending order of importance as insect hosts:

• Oaks
• Willows
• Cherries and Plums
• Birches
• Poplars, Aspens, and Cottonwoods
• Crabapples
• Blueberries, Cranberries, Dilberries, and Deer berries
• Maples (note: Not the alien Norway Maple, which has escaped cultivation)
• Pines
• Elms
• Hickories
• Hawthorns
• Alders
• Spruces
• Ashes
• Basswood
• Hazelnut
• Walnuts and Butternut
• American Beech
• Chestnuts

Shrubs, Vines and Plants for Landscapes and Lawns

An appendix to Tallamy’s book includes lists of Latin and common names for native plants with wildlife value that are desirable for landscaping in the U.S. Mid-Atlantic, Southeast, Southwest, and Pacific Northwest.

Butterflies and Moths

Another extensive appendix lists butterflies and showy moths and their host plants. A chapter on gardening for diversity includes color photographs of some of the species he lists.

The Human Relationship to Natives is Clear

Tallamy points out that insects have done fine without humans and will continue to do fine when we are gone. ‚”If insects were to disappear, however,” he says, ‚”our own extinction would not be far behind.”