Good news for gardeners who care about the environment. By choosing plants in your garden, you can make a significant positive impact.
How to choose plants? I remember wanting flowers when I started gardening. I think for many of us, our plant choices were primarily based on aesthetics and functionality. wanted not only familiar plants, but also the latest horticultural varieties.
After that, I started hearing news about declining bird populations, bee colony collapse disorders, and monarch butterflies being in trouble. So we started adding plants to the garden that could support birds, bees and butterflies.
In addition to planting for pollinators, you should also plant for caterpillars. This is the message of Douglas Tallamy, Professor of Entomology and Wildlife Ecology at the University of Delaware. He has pioneered research into the importance of native plants to declining insect and bird populations. He has authored several books (three are available in the library) and has published numerous videos on YouTube. According to him, caterpillars are important for healthy ecosystem food webs because they transfer more energy from plants to other animals than other types of plant-eating animals.As he states in his December 2022 article fine gardening“Knowing how healthy the caterpillar population is is giving us a look at the health of the ecosystem.”
Additionally, 96% of the country’s land birds feed their juveniles on insects, and caterpillars are considered the best food for juveniles. Caterpillars are larger and softer than other insects, making them easier for chicks to digest.
If insects, including caterpillars, are important components of the food web, the next question is which plants are best suited to support them. clearly shows that there is A small percentage of leaf-eating insects are generalists who can eat a wide variety of plants. However, most leaf-eating insects are specialists in edible plants, often confined to one plant genus or family. Plants develop chemical and physical defenses to avoid being eaten. Specialized insects must have co-evolved with specific plant lineages for thousands of years to overcome these defenses. That is why native plants host more insects than non-native plants. A good example of this is the monarch butterfly, which has a long evolutionary history with milkweed, allowing monarch butterfly larvae to eat the plant without being poisoned by its toxic chemicals.
Non-native plants are not evil per se (although non-native invasive plants should be avoided at all costs). Non-natives are plants that have not aged sufficiently to evolve a relationship with the insects that live here. This is true even for plants like Ginkgo, which have been cultivated in the United States for 400 years. Exotic plants are problematic because they provide little support for insect activity and adversely affect the entire food web.
We need to grow native plants, but not just native plants. One of his most important results of Talami’s research is the concept of the ‘keystone plant’. This is a finding that some native plants have a much greater impact than others in terms of supporting caterpillars. He emphasizes: “We can maintain a landscape composed of 100% native plants, but we have chosen native species that do not produce much food, so they are hardly supported.” Only 5% of (plural) revealed that he was only 5%. genus) support 75% of caterpillars, and only 14% of native plant genera support 90% of caterpillars. These plants, mostly trees and shrubs, are what Talami calls “keystone” plants.
To find out what your local keystone plant is, visit the National Wildlife Federation’s website at nwf.org/NativePlantFinder/. Enter your zip code to set your location and see the trees, shrubs, flowers and grasses native to your area, ranked by the number of butterfly and moth species that use them as hosts for their caterpillars. increase.
The top 10 native plants for Eureka (95501) are: Willow (supports 328 caterpillar species). Oaks (275); Bitter Cherry/Chokecherry (262); Aspen/Cottonwood/Poplar (230); Beach Pine (220 species); Red Alder/White Alder (202); /vine maple/mountain maple (120); ceanothus (120); and ground fir/white fir (117). (Note that these figures apply only to native plant species; Japanese maple, for example, most likely supports about half the number of caterpillar species listed.)
Talamy doesn’t encourage people to plant only native plants, but he encourages us to focus on planting keystone trees and shrubs. If we gardeners follow this advice, we can leave many small non-native flowering plants in our gardens. In the case, Talami points out that birds eat most of the caterpillars before they become very large and usually damage the leaves significantly. It gives us the opportunity to actively promote the survival of birds, bees, butterflies and other insects that are very important to our health.
Donna Wildearth (She/She) is passionate about plants and is a retired teacher and landscape designer.