10 Steps You Can Take to Support Local Biodiversity – Advice from Dr. Doug Tallamy

Widely reported declines of insect abundance and diversity at global scales have left many wondering what personal actions they can take to restore local insect populations and bring balance to the ecosystems those insects serve. Dr. Doug Tallamy, a Professor at the University of Delaware, is the author of the New York Times best seller, ‘Nature’s Best Hope,’ which outlines approaches that homeowners and landowners can adopt to provide local refuge to imperiled insect and bird populations.  Earlier this month, Dr. Tallamy delivered a seminar to the Penn State Entomology Department, where he outlined 10 basic steps to combat insect declines and support local biodiversity.

Step 1: Reduce the size of your lawn

Americans love green lawns. It’s estimated that 40 million acres, or roughly 2% of the landmass of the United States, is planted with turfgrass.¹ While turfgrass is pleasant to walk on, it offers no ecological benefits. Dr. Tallamy recommends reducing your lawn size by half, and planting the remainder with native species.

Step 2: Remove non-native plant species and replace them with natives

Not only do non-native species offer little to no benefits for local wildlife, they can also escape cultivation and invade local ecosystems; preventing the growth of native species and further contributing to declines in insect abundance and biodiversity.²

Native plantings do not necessarily need to look wild or unkempt; it is possible to have well-manicured yards and gardens cultivated with native plant species rather than non-natives. While you may not want to replace all of the non-native ornamentals in your yard, Dr. Tallamy recommends reducing as much as possible. He advises having no more than 30% of the yard dedicated to non-native species. 

Step 3: Prioritize planting keystone genera

Some genera of native plants are called keystone genera, meaning that they are essential for helping support local ecosystems. Without these genera, local food webs can collapse.  Dr. Tallamy’s lab researches plants that serve as keystone genera here in the eastern U.S., which include: oaks, cherries, willows, birches, cottonwood elms, goldenrods, asters, and sunflowers.

There are many cultivated, non-native varieties of the plants referenced above which do not perform as well as native, locally adapted cultivars. When shopping for plants, be sure to buy species or varieties that are native to your region. The closer to home the seeds and/or cuttings were collected, the better!

Step 4: Design plantings aimed at supporting native bees and caterpillars

Native bees and caterpillars are crucial to the survival of local food webs. Native bees are generally the most effective pollinators of native plants, and adequate pollination is essential for ensuring the plant will set fruit and/or seed. These native fruits and seeds provide valuable food sources for many wildlife species. Additionally, caterpillars are important food sources for wildlife, particularly for young birds. Research from Dr. Tallamy’s lab indicates that for 80% of bird families, caterpillars are the dominate component of nestling diets. In fact, Dr. Tallamy found that it can take between 6,000 to 9,000 caterpillars to rear just a single clutch of chickadees!

Photo by Dr. Doug Tallamy

Step 5: Plant with specialist species in mind

Related to Step 4, many native bees and caterpillar species are specialists, meaning that they will only feed on certain plant genera. If you want to attract these species to your yard, you’ll need to figure out what plants they specialize on. For example, if you’re interested in helping to support monarch butterfly populations, one of the best things you can do is to plant milkweed in your yard, as it is the only plant the species will feed on during its larval form.

Step 6: Think you’ve planted enough? Try planting some more!

Seriously, the more the better! Try to maximize the ecological potential of your property. It doesn’t matter if you live on a quarter acre lot in the heart of a major city, a multiacre property in the country, or something in between. Whatever amount of land you’re able to transform in favor of local biodiversity can and will make a difference. If you don’t own property, consider helping a friend or relative transform theirs!

Step 7: Reduce light pollution

Artificial light can disrupt insect navigation, resulting in confusion and disorientation. This can make it more difficult for nocturnal insects to find mates,or locate essential breeding habitats and food resources.³ Insects attracted to outdoor lights often get caught swirling around them, making them easy targets for predators or causing them to die from exhaustion.

Luckily there are some simple steps you can take to reduce light pollution around your home. Dr. Tallamy recommends installing motion activated lights and replacing white light blubs with less disorienting yellow bulbs.

Step 8: Provide places for insects to nest and overwinter

Next fall, when the leaves begin to blanket your yard, don’t reach for the rake! That ground cover likely contains insects that dropped from trees to pupate in the soil or duff, and the leaves provide them with protection. Fallen leaves can also serve as valuable nesting or bedding material for wildlife, and will act as a natural mulch, suppressing weeds and restoring nutrients to the soil as they decompose.

Dr. Tallamy also recommends layering low growing or annual plant species in the understory of trees and shrubs, which will provide nice coverage while still allowing access to the dirt – ideal for caterpillars looking for a safe location to pupate, or solitary ground-nesting bees looking for a nest site!

Step 9: Avoid using pesticides and fertilizers

Fungicides, insecticides, herbicides, rodenticides, and synthetic fertilizers all introduce additional chemicals into your garden habitat that insects are much better off without. When gardening for nature, it is best to avoid these chemicals to keep local wildlife safe from exposure.

The natural world has a way of self-regulating, and when you prioritize planting native species you also attract predators and natural enemies to your yard which can help suppress pest populations. Native plants tend not to need a lot of fertilizer, so soil health can easily be maintained by using naturally derived compost and mulch (leaving those leaves in the yard, as mentioned in step 8, can help with this!).

Step 10: Help others in your community get started!

What’s better than having a vibrant yard, blossoming with native plant species and abuzz with insects and wildlife? Having an entire neighborhood with yards like that! Collect seeds or dig up rhizomes from your yard to share with others in your community. Or help by offering advice on where to source plants locally, and provide tips and tricks you’ve picked up along the way. The more land we can convert away from being a wildlife food desert, the better. If your city or homeowners association has rules preventing you from converting to a more native landscape, organize with neighbors and community members to change them!

For more information on how to get started, including links to nonprofits organizations, native plant purveyors, and landscapers who specialize in native designs, you can visit Dr. Tallamy’s website RESOURCES — HOMEGROWN NATIONAL PARK. His book, Nature’s Best Hope, can be found in the landscaping or nature section of most book stores.

1. Milesi, C., S. W. Running, C. D. Elvidge, J. B. Dietz, B. T. Tuttle, and R. R. Nemani. 2005. Mapping and Modeling the Biogeochemical Cycling of Turf Grasses in the United States. Environmental Management 36:426–438.
2. Litt, A. R., E. E. Cord, T. E. Fulbright, and G. L. Schuster. 2014. Effects of Invasive Plants on Arthropods. Conservation Biology 28:1532–1549.
3. Owens, A. C. S., P. Cochard, J. Durrant, B. Farnworth, E. K. Perkin, and B. Seymoure. 2020. Light pollution is a driver of insect declines. Biological Conservation 241:108259.