By Astrid Cook-Dail, NC State Extension Master GardenerSM volunteer intern of Durham County
One person’s trash is an insect’s treasure? The bug snug is just that. Pruned hollow stems, fallen leaves, seed heads, and twigs are great for the compost pile, but you can also use fall yard waste to build both biodiversity and healthy soil in your landscape. (Image credit: Astrid Cook)
What is a Bug Snug?
A “bug snug” is a name for a small teepee or similar structure built in late summer or early autumn and packed with leaves and other garden detritus often gathered during autumn garden cleanup or tidying. Bug snugs are similar to insect or bee hotels in that they provide insect and arachnid (bugs, generally) habitat.
Why Make a Bug Snug?
Bug snugs are a great place for all types of important creatures to overwinter during the colder months. By using a combination of leaf litter, deadheaded flowers, and plant stems, you can provide a variety of nesting types for different insects. These are the primary habitat features insects use to survive the colder months.1 Many insects such as butterflies, moths, and beetles overwinter in leaf litter, and the bug snug also provides additional protection to the soil surface where some insects overwinter underground, such as ground nesting bees.
Not only does making a bug snug help provide habitat to insects, but by supporting insects, you also support other animals further up the food chain such as birds, 96% of whom depend on a healthy population of insects to eat overwinter and feed to their young.2
Furthermore, it can be a nice design accent in the garden if there is an area that you are tidying up in the fall. While leaving the leaves and plants intact – without trimming or shredding – through the winter is key to supporting next year’s insects, oftentimes there is a small area that may be preferred to be a bit more tidy. If that is the case, then you can make use of those garden trimmings in an intentional way by building a bug snug. Best of all, this project takes almost no time and is free to make if you have a few sturdy branches around!
The bug snug should remain in place until May, or when temperatures consistently rise above 50F for at least one week, which is the time insects break dormancy and resume activity. Xerces Society for Invertebrate Conservation provides additional cues to determine when insects have finished overwintering and the proper time to disassemble your bug snug. And as simply as you put the bug snug together in the autumn, you can take it apart just by removing the branches used to make the structure holding in the leaf litter and stems.
How to Construct a Bug Snug
Materials
3 tall branches or wooden stakes
Leaves, twigs, hollow stems, and debris from autumn garden cleanup
Jute twine
(Image credit: Astrid Cook)
Step 1: Gather all materials. Here, I have leaves, vines, and flower stems, as well as wooden stakes.
(Image credit: Astrid Cook)
Step 2: Position the stakes to make a tripod and tie securely with twine.
(Image credit: Astrid Cook)
Step 3: Fill with leaf litter and garden trimmings, alternating layers of hollow stems with leaves for airflow and to provide different overwintering habitats.
On the blog, more about the benefits leaving fall leaves and photos of insects in their different stages that would benefit from a bug snug: https://wp.me/p2nIr1-5bS
By Jeannie Arnts , North Carolina Extension Master GardenerSM volunteer of Durham County
I have volunteered as a recorder for the New Hope Bird Alliance (formerly Audubon) Bird Friendly Habitat (BFH) team since 2018. The BFH team, consisting of a plant expert and a recorder, visits homeowners’ yards to identify native and invasive plants and make recommendations for improvements to achieve an ecologically beneficial habitat for birds, insects, and other wildlife. Since I have joined the group, plants previously recognized as non-native, non-invasive plants have been moved onto the “Watch List” or “Lesser Threat Invasive” list. Other plants previously considered lower threat have been moved to a higher threat category. The question arises, “What is it that changes a benign non-native into an invasive?
When is a Plant Determined to be Invasive?
Plants are categorized as invasive once they disrupt the ecology of intact, functioning eco-systems, leading to loss of biodiversity and habitat degradation. This results in huge economic damage valued in the billions of dollars to agriculture, forestry, and personal property. Invasive plants compete with our natives for critical and often limited resources like sunlight, water, nutrients, soil, and space. Anyone who has ridden the train at the Museum of Life and Science in Durham and seen the Russian olive shrubs (Elaeagnus sp) overtaking the landscape along the tracks or been on a hiking trail in many Triangle forests and seen the stiltgrass (Microstegium vimineum) engulfing the entire ground cover of the forest floor can easily see the impact of invasive species.
Russian olive shrubs (left) out-compete native plants and dominate riparian areas primarily in central and western USA. Japanese stiltgrass (right) was accidentally introduced into Tennessee around 1919 as a result of being used as packing material for porcelain from China. it has invaded many woodlands in North Carolina. (Image credit: NC State Cooperative Extension)
What Factors Influence a Plant to Become Invasive?
Biologists have been “vexed for decades” by the question of what causes some plants, once thought to be benign, non-invasive exotics, to become a risk to our eco-systems due to their invasive characteristics. The ecologist, Charles Elton, wrote the book, The Ecology of Invasions by Plants and Animals, in 1958 and, more than 100 years earlier, Charles Darwin pondered this question during his voyage on the Beagle (1831-1836). Johnny Randall, former Director of Conservation Programs at the NC Botanical Garden, noted that one reason plants become invasive is that in their new environment, they no longer have natural controls, such as pests, pathogens, and herbivores. This gives them an advantage over native plants that have been part of a region’s ecology for millennia; consequently, the invasives often out compete the natives.1
In addition, a plant’s propensity to become invasive is a function of the plant’s own biology, including a relatively short generational period, large seed production, its ability to reproduce asexually (without the need for fertilization), and having large fleshy fruits, such as those produced by Autumn or Russian olive trees (Elaeagnus sp), privet (Ligustrum sp.) and heavenly bamboo (Nandina sp.) With this latter trait, birds will eat the berries and deposit the seeds far from the original location of the plant.
A non-native, is especially prone to invasion when it sets its roots in a “matched habitat” similar from which it came, i.e., their native ranges tend to have similar temperature extremes, precipitation levels, and seasonal cycles. Stiltgrass (Microstegium vimineum) is an example of a plant that meets most of the criteria for becoming invasive. It is an annual that produces up to 1000 seeds per year, has no natural controls, reproduces asexually, and its seeds are distributed by the wind. In addition, the seed bank may take up to five years to germinate. Many gardeners who think they have eliminated stiltgrass on their property one year are befuddled to find a number of plants from the seed bank sprouting the next summer. The good news is that if you continue to manage the stiltgrass, you will have fewer plants each year.
Beloved Plants that Become Invasive
I think we can all agree that we want stiltgrass eliminated from our property, but there are non-native plants that have been beloved by gardeners for generations that are being added to the invasive lists, much to the consternation of gardeners. One example is the lenten rose (Helleborus orientalis).
Some hellebores have started to escape into woodland areas and are able to stifle our favorite native understory flowers. They prevent seedlings of other plants from getting established as dense mats of their offspring grow. (Image credit: NC Extension Toolbox, Bob Gutowski CC-BY-NC-SA-2.0; Jim Robbins CC-BY-NC-4.0).
There are many good reasons that hellebores are such a beloved plant: they bloom over the winter months when very few other plants are blooming; they require little care; they are deer and rabbit resistant; they tolerate a wide range of light conditions; including light shade; and they survive even deep frosts. Unfortunately, they meet many of the conditions that place them at risk to become invasive in our region: they have no natural pests or pathogens; they can successfully fertilize themselves (although bees will seek nectar and pollen from the plants); and they produce a multitude of fertile seeds. While there is not a perfect native substitute for hellebores, the gardener may consider planting a matrix of sedges (Carex species), coral bells (Heuchera americana), and ferns, many of which are host plants, to provide winter interest .
While not yet on the invasive lists in N.C, another beloved plant that is of concern is the crape myrtle (Lagerstroemai indica). Its spread is being tracked in Southern states by the Invasive Atlas of the United States and the plant’s spread is being watched with caution by conservationists in N.C. Each flower of the crape myrtle produces a prodigious number of seeds that are carried or blown far from the mother plant. I have had a crape myrtle in my yard for probably the past 40 years and it has only been recently that I have seen it sprouting up elsewhere in my yard and ¼ acre woods.
Crape myrtles are seen along roadways and in gardens in North Carolina but conservationists have raised concerns because it outcompetes many native plants (Image credit: NC Plant Toolbox, skdavidson)
Liriope (Liriope muscari and L. spicata), bugleweed (Ajuga reptens), Rose of Sharon (Hibiscus syriacus), and ox-eye daisy (Leucanthemum vulgare) are all common ornamental plants that have been added to the NC Invasive Plant list as “Low Threat” species. While they have the potential to harm our local ecology, they are not yet doing so.
Liriope (Liriope muscari), bugleweed (Ajuga reptens), Rose of Sharon (Hibiscus syriacus), and ox-eye daisy (Leucanthemum vulgare) are plants that many of us have in our garden. They are considered to be “Low Threat” to native plants of North Carolina. (Image credit: North Carolina Toobox, Manuel-CC-BY-2.0; Jim Robbins-CC-BY-NC-ND; Frank Mayfield, CC-BY-SA-2.0)
As gardeners, we can control the spread of potentially invasive plants in our own yards or we can choose to remove them and plant a native that supports our native ecology. A follow-up blog will suggest options to consider for replacing invasive plants with natives that power our ecosystems.
Notes
Personal communications Peter Schubert, NC Invasive Plant Council, October, 2024 and Johnny Randall, former Director of Conservation Programs, NC Botanical Garden, October 2024.
Grzędzicka, E., Assessment of Habitat Selection by Invasive Plants and Conditions with the Best Performance of Invasiveness Traits, February, 2023. https://www.mdpi.com/1424-2818/15/3/333
