Gardening for the Environment: The essential link between insects, animals, and plants

July 5, 2019

Most people have heard that monarch butterflies and bees have declined drastically in the last 20 years, but not as many people know that other insects are also decreasing.

 

Hummingbird Moth, also known as Hawk Moth.

Scientists have found that we’re losing insects and other bugs worldwide at a rapid rate due to pesticides and loss of habitat.

 

Surveys from different countries in the last few years have shown losses of as much as 80 percent to 90 percent for many species, and scientists are scrambling to find more data from years past and conduct comparable studies today, to measure the problem.

 

It has been called an insect Armageddon or apocalypse. 

 

Most of us would be happy to have fewer cockroaches, houseflies, stinkbugs, mosquitoes, spiders, and ticks, but, unfortunately, those common pests probably are not at risk. 

 

Photo: Photinus pyralis, also known as a firefly or lightning bug.

 

We would miss the butterflies and fireflies, the luna moths, and dragonflies, but what would the consequences of a general insect Armageddon be?

 

What importance do insects actually have? You may be surprised to learn that they are essential links in the ecosystem.

 

Insects are the critical starting point in the food chain for many animals. Birds, frogs, reptiles, some freshwater fish, and small mammals all eat insects.

 

Many of these animals are declining worldwide, for various reasons, but the continuing decline in the number of insects is a big factor.

 

Bigger birds, snakes, fish, and mammals rely on these smaller animals for food, so their numbers are dropping, too, as their food sources decline. This also affects the predators that hunt these animals, and many of them are disappearing, too. 

 

Native pollinating insects, as well as important non-native pollinators like honeybees, are showing huge losses.  See honey bee photo below.

 

Nobody realized until the honeybees started to disappear how many of our crops were pollinated by wild native insects, instead of honeybees, and the wild ones have also gone missing. Between them, they are responsible for our fruit, grapes, and berries, soybeans and other beans, tomatoes, peppers, squash, eggplant, cucumbers, avocados, okra, nuts, coffee, some oil seeds, some spices, buckwheat, probably many more. I’m getting hungry already!

 

Also cotton, and the seeds for many other crops. I’ve tried to hand pollinate my pawpaw trees, and I’ve never been successful, so it’s not the easiest thing to do. We really do need the insects!

 

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I started gardening in 2003 because I was interested in the environment, in forests, in our ecosystem, and how native plants and animals need each other. For 16 years I’ve tried to remove non-native, invasive plants; protect, plant, and advocate for native plants; grow trees; and understand the connections between soil, plants, animals, fungus, and the ways our actions affect them. I know many people are skeptical of the need for these efforts, but now there’s proof that our ecosystem needs our help. A silent spring is almost here. Where is a new Rachel Carson to inspire us to take action?

 

One of the most important things we can do now as gardeners, as homeowners, or as members of a homeowners’ association, is to stop using pesticides, and ask our neighbors and landscapers to stop using them. We can refuse to buy plants or seeds that were treated with systemic pesticides and ask the nurseries where we shop not to use them.

 

Ladybug

Your family and your pets will be healthier, and you’ll give nature a chance. If going totally pesticide-free sounds daunting, try Integrated Pest Management (IPM), a system in which pesticides are used only as a last resort. Montgomery Township uses IPM on all its property.

 

Another important step we can take is to refrain from planting invasive plants and use native plants instead of non-native plants. Right now, our lawns aren’t native, most of our weeds aren’t native, most of our garden flowers aren’t native, and most of our shrubs and ornamental trees aren’t native. Often our wildflower meadows are full of wildflowers from around the world, instead of native wildflowers. However, a majority of our shade trees are native, at least here in Montgomery. 

 

Most insects have a host plant, or a few host plants, that their larvae can eat. For monarch butterflies, it is milkweed, any variety. Other insects have other host plants, and it makes sense that they evolved over millennia to survive on plants native to the places where they live. 

 

When insect larvae mature into adults, their diet changes.  For example, pollinators live on nectar and pollen from flowers. Some insects can hover in the air and reach into tubular flowers to gather nectar. Some are small enough to crawl into the same tubular flowers. Some have to land on the flowers, and they need large, flat flowers, like black-eyed susans and coneflowers, or clusters of flowers. 

 

Not all insects can see all colors, and they ignore flowers whose colors they can’t see. Some insects, such as moths, come out at night, so they need flowers that stay open at night. And each insect needs nectar and pollen every day, all summer. That’s why we should be filling our gardens with a wide variety of native flowers, skipping the double curly flowers, the alien flowers, the hybrids. 

 

Some insects may be able to get nectar and pollen from some non-native flowers, but usually they need a native host plant. That’s why we should also plant native trees, which serve as host plants to many more insects than garden flowers do. If you plant it, they will come.

 

If anyone wants to plant some native plants or rewild part of your lawn, contact me and I’ll give you some. (email: kops-and-robs@comcast.net.)

 

A few gardeners who don’t use pesticides and who do plant native plants won’t halt the insect apocalypse, but perhaps we can work together and create some safe havens for the wildlife we have left, hoping that our governments will wake up to the need to protect our ecosystems, that more landowners will help, and that the plants and insects and other wildlife we protect can survive and someday thrive and spread. Today I did kill a centipede in my house, but I don’t want to find out what life is like without bugs. 

 

Sarah Roberts has lived in Montgomery since 1986. She raised two children, and is a volunteer with the Sustainable Montgomery Committee. Her husband, Larry Koplik, is chair of the Montgomery Shade Tree Committee, and both are concerned abut the environment. Roberts is an advocate for native plants and a busy gardener. In her spare time she likes to do English and American country dance. She is originally from Bloomington, Indiana, and has a bachelor's degree in civil engineering. She is a licensed professional engineer. 

 

For questions about her column, email her at: kops-and-robs@comcast.net.

 

 

If you want to know more, there’s a good article summarizing a lot of different research on the subject on The New York Times. ■

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