Why Natives Matter: Bees, Butterflies, and Bugs

Last week I wrote about how using Georgia’s native plants in our landscaping helps to give our gardens and landscapes a sense of place. In this post, I’d like to briefly cover why using native plants matters to our native insects. Why briefly? Well, because people have written whole books on this topic (see Doug Tallamy’s first and third books to learn more), and I am not the expert.

As you may know, plants and insects have evolved over millions of years; what you may not realize is that they did it together. A series of mutually beneficial changes took place over millions of years until we have the plants and insects we have today. Some of them are linked together in ways that affect their very survival; the life cycle of the Monarch butterfly and its relationship to milkweed is more well-known than ever and a great way to understand the host plant relationship. 

The cloudless sulphur butterfly (shown at left) is abundant today thanks to natives like partridge pea (Chamaecrista fasciculata).

Occasionally, someone will argue that having new plants introduced (e.g., brought here from somewhere else) increases the biodiversity and proposes that that must be an improvement. However, given the complex evolutionary relationship between insects and plants, there are 3 potential problems with introducing new plants:

1. They do not immediately contribute to the food web that supports native insects; often offering only pollen and/or nectar. Native insects cannot complete their life cycle on them (i.e., lay eggs on their and have their young eat some of the foliage). There are some limited exceptions, of course, when non-native plants are closely related to native plants such as the ability of parsley and fennel to support Eastern black swallowtail butterfly caterpillars. 

2. They displace native plants that do contribute to the food web, thereby reducing the amount of insects that can be supported in the same square footage. 

3. They become invasive sometimes, displacing more native plants as they invade natural areas, and thus further reducing the amount of insects in the area.

 

Zebra swallowtail will only lay eggs on native pawpaw

Native plants support insects and pollinators far better than non-native plants – that is proven in study after study after study. From bees, to butterflies, to many of the other bug categories (flies, wasps, beetles) that depend on plants, native plants give so much more to the ecosystem than pretty flowers or even pollen and nectar. They aren’t just there, they contribute.

In the case of closely linked relationships, if a plant population were to decline too much, specialist pollinators populations would decline as well, resulting in a mutually destructive downward spiral towards extinction for both. Even for generalist plant-pollinator relationships, a decline in insects yields a decline in pollination resulting in fewer viable fruits/seeds and a decline in the diversity of plants.

If contributing to the insect population--bees, butterflies, and other bugs--matters to you, increasing the percentage (and variety) of native plants in your landscapes makes a difference.

This has been installment two in my series on Why Natives Matter. If you missed the first one, you can read it here: Sense of Place.

Rose-mallow bee is a specialist on Hibiscus