After World War II, suburbs sprang up across America. These new landscapes often included Chinese and European ornamental flowers, trees, and shrubs that were (and still are) available at local garden centers. Unfortunately, because these plants came from afar, they contributed very little to local foodwebs. The backbone of all foodwebs is native plants. Think of a foodweb in terms of a plant-eating caterpillar, which is eaten by an insect-eating bird that feeds caterpillars to its young, which may be eaten by a meat-eating owl. Our human survival depends on functioning foodwebs.
Native plants are the backbone of a foodweb; insects are its lifeblood.
As stated by Douglas Tallamy in Bringing Nature Home, “Because so many animals depend partially or entirely on insect protein for food, a land without insects is a land without most forms of higher life.” Or, stated more forcefully by E.O. Wilson, University Research Professor Emeritus at Harvard University, “If insects were to vanish, the environment would collapse into chaos.”
Insects, which are crucial in our foodwebs, can be picky eaters.
Like the child who eats only macaroni and cheese and chicken fingers, many insects stick to a limited food
menu. The classic example is the monarch/milkweed relationship. Monarch butterflies lay their eggs exclusively on milkweed plants; monarch caterpillars eat only milkweed. If there isn’t any milkweed, a monarch caterpillar will not crawl away to eat marigolds, geraniums, or oak leaves.
Plants are to blame for making insects such fussy eaters. Like any living thing, plants prefer not to be eaten. Over thousands, perhaps millions, of years, plants have developed chemical defenses that, over evolutionary time, keep most plants from being eaten by most insects. However, insect herbivores need to eat plants to survive. So, by living side-by-side, or co-evolving, with native plants, certain insects have developed certain adaptations that have allowed them to “crack the chemical code” of certain plants. Most insects cannot digest the recipe of chemicals that makes up the milkweed. But, through co-evolution, the monarch has figured it out.
By understanding that what we plant matters, we can take a fresh look at our own yards.
What if we considered sharing more of our yards with wildlife? Do our local landscapes adequately nourish our local beneficial insects? Given the foundation of trees, shrubs, grasses, and flowers already growing in our landscapes, what could each of us do to create a richer, more biodiverse foodweb in our Mendota Heights yards? Some of the answers lie in making more robust use of native plants in our landscapes.
Future editions of this column will explore how suburban landscapes are becoming “last refuges” for wildlife and the important role our own landscapes, no matter how large or small, play in building biodiversity. Articles will explore how to attract more pollinators, birds, insects, and other wildlife to our yards; why, despite their seeming abundance, many insect species are in decline; how to create “pollinator corridors”; the difference between beneficial insects and insect pests; how to garden for clean water; and the reason why we need more native trees, shrubs, flowers, and grasses in our Mendota Heights yards—without sacrificing the non-native plants that we love and enjoy.