Insects in our ecosystem
Our ecosystem depends on invertebrates. How can we help?
by Abby Henkel, Communications Director
This article originally appeared in the summer 2020 issue of The Twig, our member newsletter. To see more articles and past issues, click here.
Cover photo by Rick Malad, @cadmea: A mining bee visits spring beauty, a delicate spring ephemeral flower, at the Malad Preserve in Monroe County, a private property in Owen County protected by a conservation easement through Sycamore.
RESPECT OUR ELDERS
Everyone who’s ever been a kid has heard the admonishment “respect your elders,” and with good reason. Our grandparents have been around a lot longer than us; they’re wiser; and they’ve seen some things. We show our elders respect because without them, we wouldn’t be living on this glorious planet.
In fact, there are elders who walk, fly, scoot, and swim among us who don’t always get the appreciation they deserve for perpetuating life on aforementioned glorious planet. Maybe it’s the exoskeletons…
You don’t have to be an entomophile to appreciate this prehistoric class of organisms. Indeed, the oldest insects evolved alongside the oldest land plants as long ago as the Late Silurian or Early Devonian periods – some 330- 430 million years ago, when Indiana was still covered by sea.
Insect evolution and adaptation are thousands of millennia ahead of humans (the oldest known primate dates back about eight million years). Among insects you’ll find astounding diversity, unrivaled roles in the ecosystem, curious symbiotic relationships, and enviable ingenuity. With names like false potato beetle, the badwing moth, and masked hunter, Indiana alone is teeming with cool bugs.
But like so many other creatures, insects face unprecedented human-caused extinction. Biologist and conservationist E.O. Wilson has dubbed this a “biodiversity crisis,” in which scientists predict “a large portion of this planet’s biological diversity may be lost forever” (Scott Richard Shaw, Planet of the Bugs).
You’re not alone if you get creeped out by insects. But if you make it through this article and still never want to see another katydid in your life, you might at least walk away with a deeper appreciation for – and, dare I hope, excitement about? – the little creatures that keep our farms and forests healthy.
insect: an arthropod with a well-defined head, thorax, and abdomen; only three pairs of legs; and typically one or two pairs of wings (Merriam-Webster)
SIX LEGS, MILLIONS OF SPECIES
On a macro level, insects are mind-boggling. The more we study them, the more we realize how much more information
is beyond our reach:
- Insects account for 80% of all known animal species
- There are 1 million known species of insects; scientists believe there are another three million or more yet to be discovered
- The world’s insect biomass outweighs that of humans by 17 times
New species are being discovered all the time. Scott Richard Shaw, professor of entomology at the University of Wyoming, Laramie, and author of the book Planet of the Bugs, has discovered more than 150 insect species with names like Aleiodes shakirae, a parasitic wasp of Ecuador that causes its host caterpillar to contort as if belly dancing. A new species of spider, Islandiana lewisi, was discovered in 2018 in a Johnson County, IN, cave by Julian Lewis of the Indiana Karst Conservancy.
In Indiana, the Class Insecta (six-legged arthropods, or insects) has enormous diversity. Insects of the Great Lakes Region (Dunn 2007) lists 28 orders, with familiar categories like Dragonflies and Damselflies; Beetles and Weevils; Termites; and Butterflies, Moths, and Skippers. Then there are lesser-known orders like Proturans; Scorpionflies and Hangingflies; and Sucking Lice. There are at least 2,678 known beetle species in Indiana – about double the number seen in more northern Midwestern states. Among butterflies and skippers, 149 species have been recorded.
Each species plays a role in our ecosystem, from opportunists like the common eastern bumble bee which consumes nectar from many types of flowers and crops, to the hackberry nipple gall-making psyllid which relies on the hackberry tree leaves to lay its eggs in tiny, harmless yellow galls.
A great spangled fritillary perches on native butterfly weed at Fish Creek Preserve, a private property in Owen County owned by Myriam Wood and protected by a Sycamore conservation easement.
AN ECOSYSTEM HELD TOGETHER BY INSECTS
Insects are naturally hardy creatures for the most part, and they’ve survived a lot. That asteroid that killed the big dinosaurs 65 million years ago? Many insect species just kept on flourishing, along with what we now know as birds. With 400 million years of history, insects have seen their share of troubles, but can usually adapt or evolve and carry on.
But an unprecedented challenge is wreaking havoc on bugs. According to a global meta-study published in the journal Biological Conservation in 2019, loss of habitat is the single greatest contributor to insect population decline. Other major factors include pollution such as agricultural insecticides, pathogens and introduced species, and climate change. As the authors of this scientific review state:
“Species extinctions equally impact the overall biomass of entire ecosystems, as insects form the base that supports intricate food webs.”
Consider hill-building ants. A Swedish study found what can happen to a forest when wood ants such as those in Indiana forests are excluded from the forest floor.
- No ant predators leads herbs to grow prolifically
- More herbs decay into soil, increasing nutrient content
- Bacteria population skyrockets
- Decomposition of old and dead plants skyrockets
- Stored carbon is broken down much faster
- Forest releases 15% more carbon and nitrogen into atmosphere
We think of trees as the carbon heroes of the forest, and indeed their biomass is critical to containing the carbon that contributes to climate change.
But without the tiny foragers of the forest floor, everything is thrown off balance. Wood ants do more than just break down dead organic matter. Trilliums are beautiful little woodland plants whose seeds have elaiosomes, or little fleshy matter attached to seeds. Wood ants collect these seeds, bring them to their nests, and inadvertently plant them. The ants get food and the trillium propagates – a win-win.
Insects are a critical part of the food web: 96% of terrestrial birds in North America rely on insects and other arthropods to feed their young. On Sycamore’s land, endangered birds like Henslow’s sparrows and cerulean warblers rely on small insects for sustenance. With a 33% decrease in North America’s bird population over the past fifty years, the impacts of a diminishing insect population and habitat destruction are already playing out. As much as I appreciate insects in their own right, it does make me happy to observe a hungry bird feasting on a six-legged snack.
There are many other animal species found on Sycamore’s nature preserves that depend on insects for survival. Indiana bats, which are both federally and state endangered and roost at Beanblossom Bottoms Nature Preserve, hunt insects as their only source of food. Eastern box turtles, a species of special concern in Indiana, are especially carnivorous in their younger years.
What happens to these species when insects are in short supply?
WE’RE LOSING OUR BUGS
Findings from a 2016 study by the Intergovernmental Science-Policy Platform on Biodiversity and Ecosystem Services (IPBES) predict that a staggering 40% of all insect species face extinction due to human causes. “Save the pollinators” has become a trendy catchphrase, but it comes from a deeply important need to protect the insects we depend on for survival.
- $57 billion in ecosystem benefits are provided by insects
- 80% of the world’s wild plants use pollinator insects for seed production
- 75% of the world’s food crops depend on pollinators
- 300% increase in the volume of agricultural production is due to animal/insect pollination since 1970
Mealtime for a black-throated green warbler at Eagle Slough Natural Area in Evansville | Steve Gifford
The rusty patched bumble bee was the first wild bee (among 20,000 other bee species in North America) to be placed on the federally endangered species list. This bee traditionally made its home in Indiana and throughout the northeastern United States. Bill McCoy, a Sycamore board member and retired Refuge Manager of the Patoka River National Wildlife Refuge, believes the bee could be at the Refuge, which includes Sycamore’s 1,000- acre Columbia Mine Preserve.
“Our management program of converting farmland and reclaimed strip mines to forest and grasslands with forbs is creating ideal habitat where the bees require access to ephemeral flowers in early spring in adjacent forests before trees leaf out,” Bill told me in an email. “Columbia Mine Preserve offers an outstanding area for reintroduction if they’re not already there.”
Efforts to find the rusty patched bumble bee in historically documented places around Indiana are already underway; the Beanblossom Creek Bicentennial Conservation Area could be housing small populations of it now, Bill believes.
“The key to bringing them back,” Bill wrote, “is reintroducing them to suitable habitat in areas where neonicotinoid chemicals are not being used on adjacent farmland. The chemical is systemic, landing on flowers wherever the dust from planting blows into adjacent natural areas or running off into all nearby water sources.” Sycamore’s work to build habitat corridors and expand our footprint of protected land around Beanblossom Creek means a greater density of safe habitat in an important watershed.
Specialist species like many wild bees and ground beetles are particularly susceptible to habitat destruction. Moths require forbs and trees for overwintering locations; as these are destroyed for agriculture or construction, the adults have nowhere to lay eggs and ensure the survival of their species. Loss of stream biodiversity due to draining, diversion, and increased sedimentation is another major concern for insects.
Before settlement, one fourth of the land in Indiana was wetland in the form of bogs, swamps, fens, wet prairies, and seasonal flooded areas. Today, according to the Indiana Department of Environmental Management, less than four percent of Indiana’s land is natural wetland habitat. But with more than one third of the U.S.’s endangered species fully reliant on wetlands, we must make wetland restoration a priority if we are to protect insects, plants, wildlife, and thus our own future. Forests and grasslands in Indiana have faced similar declines. With the support of Sycamore members, we are restoring these important habitats all across southern Indiana.
CONSERVATION IS KEY
Visit a nature preserve in summer to hear it teeming with crickets, grasshoppers, bumble bees, and cicadas. You’ll see the flutter of great spangled fritillary butterflies, the flash of cypress fireflies, the whoosh across the water of swift river cruiser dragonflies. And you might not see much of them, but you’ll know that the lined acrobat ants, four-spotted handsome fungus beetles, and burrower bugs are all busy at work underfoot.
How can we help these tiny creatures thrive and expand? If habitat destruction is the leading cause of insect decline, preserving and restoring natural lands is a primary solution. On average, Sycamore acquires about 250 acres per year. Jeff Belth, author of Butterflies of Indiana, described “the barrens and glades of southern Indiana” as particularly special habitat in an email interview.
Because so much land in Indiana has been converted to farmland, Sycamore prioritizes both existing natural areas and farmland within priority conservation areas that show great potential for restoration projects. At the Sam Shine Foundation Preserve in Monroe County, for example, former pasture and hayfields are already being used by rare birds like bobolinks and dickcissels. There they find not only safe habitat for nesting, but also increasing food sources in the form of insects in the young fields and forest.
As woodlands age, their benefits to wildlife, plants, and insects increase. Old-growth forests like Sycamore’s Hoot Woods in Owen County – part of only 2,000 acres of old-growth woods remaining in Indiana – support life from the canopy down to the soil. Even dead trees house bats, rodents, birds, and wood ducks before they fall naturally in a storm or through rotting. The logs continue supporting industrious activity: “a teeming array of termites, ants, beetles, centipedes, millipedes, and other invertebrates. These in turn become food for salamanders, shrews, mice, and other denizens of the forest floor. The rotting wood is further broken down by fungi and bacteria. The wood is gradually converted to humus, replenishing the soil and completing the natural nutrient cycle.” (Indiana Department of Natural Resources)
A swift river cruiser dragonfly was spotted during a Nighttime Mothing Celebration at Eagle Slough Natural Area in 2017. | Debbie Goedde
NATIVE PLANTS RENEW HABITATS
Another critical part of conserving insect habitat is supporting native plants and controlling invasive ones. It’s not just that invasives spread and crowd out natives because they have no natural predators; invasive plants are also much less likely to be edible by native insects. In some cases, they actually contribute to the decline of insect populations.
The West Virginia white butterfly, native to Indiana, lays its eggs on the leaves of mustard plants. But it can’t readily distinguish between a native mustard such as cutleaf toothwort and invasive garlic mustard, which produces a chemical (alliarinoside) that the caterpillars are unable to process. A 2015 study published in the Journal of Chemical Ecology found that caterpillars that consumed garlic mustard leaves experienced a “significant reduction” in survival, caterpillar size, and leaf consumption. When female West Virginia whites lay too many of their eggs on garlic mustard leaves, the population quickly declines due to decreasing survival rates to adulthood.
Jeff Belth documented a 2017 trip to Sycamore’s Amy Weingartner Branigin Peninsula Preserve on Lake Monroe. He saw one West Virginia white in addition to 17 other species of moths and butterflies, including two luna moths. You can learn more about Sycamore’s recent success with controlling garlic mustard and restoring native wildflowers at this preserve in our 2019 Impact Report (sycamorelandtrust.org/impact).
Removing invasive plants clears the way for natives to recover the landscape. Sometimes the plants come back on their own, the seeds having lain dormant in the soil until they had room to germinate. At other times, we undertake carefully planned plantings to ensure a diverse balance of wildlife-friendly plants.
Black-eyed Susans and bee balm fill the Flying Flowers Garden at Touch the Earth.
The Flying Flowers Educational Garden at Touch the Earth Natural Area (Bartholomew County) was an old agricultural field overrun with invasive plants when Sycamore acquired the property in 1995 thanks to financial support from an anonymous donor and Sycamore members. Primarily we planted the preserve with native trees to revert it to forest, but also chose to plant a half-acre as prairie. In 2006, with funding from the Indiana Native Plant Society, we removed invasives at the prairie and planted six species of native grasses and 22 species of pollinator forbs like milkweeds and purple coneflower.
Asian bush honeysuckle is an invasive plant known for competing with other flowering plants to attract pollinators. Without natural predators, it grows so densely that it shades out any other plants on the forest floor. When Sycamore acquired the 188-acre Porter West Preserve from the estate of David Porter in 2008, most of the preserve was healthy hardwood forest but about 40 acres of an old composting facility housed woody invasives like bush honeysuckle and callery pear trees. With support from the Monroe County Soil and Water Conservation District and discounted services from Eco Logic LLC, we used a FECON chipper to mow down many of the largest invasive shrubs and trees in the fall of 2016. Volunteers helped treat the stumps that resprouted in the spring with an herbicide, and continue to assist with ongoing control efforts. Today, hikers are treated to a trail through a recovering natural area that supports more insect life in every season.
Douglas W. Tallamy, author of Bringing Nature Home and the professor and chair of the Department of Entomology and Wildlife Ecology at the University of Delaware, has conducted several unpublished studies comparing native and non-native plants in Pennsylvania.
- produced four times more insect biomass than non-natives did, entirely due to the inability of insects to eat the alien plants
- were associated with three times as many herbivorous insects
- supported 35 times more caterpillar biomass, the preferred source of protein for most bird nestlings
Sycamore’s planting projects planned for 2020 and 2021 include a new one-acre prairie at the Amy Weingartner Branigin Peninsula Preserve, an educational garden at Cedar Crest funded by the Raymond Foundation (both Monroe Co.), and a pollinator planting at Tangeman Woods (Bartholomew Co.). Invasive species control this year includes continued efforts to remove garlic mustard, multiflora rose, and Japanese stiltgrass at many of our preserves. Thank you to our members for making this work possible, especially as safety precautions surrounding COVID-19 lead our staff and volunteers to work independently in the field.
YOU CAN HELP
Debbie Goedde, a Master Naturalist and Sycamore member in Evansville, developed a passion for bugs at a young age while watching ants – “an endless source of entertainment,” she told me. She and her husband Bob care for their own Goedde Arthropod Sanctuary on their property. It’s their way of “making our place attractive to as many insect species as possible.”
“If you take insects for granted that they will always exist, then I think you don’t mind the loss of habitats, use of pesticides, or light pollution,” Debbie says. But once your eyes are opened – as a young child observing ants, or as an adult with a renewed appreciation for the role of insects in our ecosystem – you can start to take action.
You don’t need a big plot of land to make an arthropod sanctuary. With even a small yard or a balcony for some container gardening, you can plant native flowers and grasses and start observing the tiny ecosystem you’ve created. We’ve gathered tips, inspiration, and resources at sycamorelandtrust.org/plant-natives.
One of the most powerful ways to make an impact at home is to reduce the size of your lawn. Every bit of land that can be converted to native habitat is critical to the insects and birds at risk of extinction. Up to 40 million acres of North America are covered in lawns. Consider if even a small percentage of that were reverted to nature! I highly recommend the book Bringing Nature Home by Douglas W. Tallamy for inspiration, scientific explanations, and clear action items for diversifying your yard or green space.
Another important way to contribute to pollinator habitat is by renewing your annual Sycamore membership and spreading the word about local conservation. Every member makes a real difference. Because of you, there are more pollinators, native flowers, and inspired hikers at the land you are helping to protect and steward. Thank you!