Are Baldfaced Hornets Friends or Foes?

Distinctive white marks on their heads give baldfaced hornets their name.
Photo:  Johnny N. Dell, Bugwood

It’s been a good year for baldfaced hornets. Many people have contacted me to report their grey papery nests in trees or hanging from the eaves of their homes.

So, are they good guys or bad guys? Do they need to be controlled? It’s a matter of making an informed choice. So here are the facts.

First, baldfaced hornets aren’t hornets at all. They’re black and white yellowjackets that nest in trees, shrubs, and on buildings. Since they kill many harmful pests, they are considered beneficial.

It’s only when their nests are nearby that they pose a potential threat from stinging. Left alone, they tend to be benign. They usually only sting to defend their nests. I’ve had several walk up and down my arm peaceably. 

The white marks on their head earn them their “baldfaced” moniker. Workers measure about three-quarters of an inch long and queens are slightly larger.

In the spring, overwintering queens emerge from tree bark, stumps, logs, rock piles, and other protected spots. Each queen builds a small nest with a few brood cells, lays eggs, and gathers insects to feed the growing workers.

When those workers become adults, they take over the housekeeping duties, building and taking care of the nest, foraging for food, and tending to the growing family from eggs laid by the queen.

Baldfaced hornets’ football-shaped nest is an engineering marvel. To that first handful of paper cells, workers add layer upon layer of hexagonal combs similar to those of the honey bee.

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Buckwheat: Pollinator Friend and More

buckwheat flowers with a pollinators
Buckwheat flowers.

Where I grew up, we did not have a county fair, but instead a “Buckwheat Festival” which celebrated buckwheat pancakes. I’ve often heard stories about “old timers” planting buckwheat because it could thrive in poor soils. Buckwheat is not as well known or common as it was several years ago; however, it does have the potential to be a great addition to your landscape and would be a wonderful summer cover crop, which is just one way to help improve soils for a more climate- resilient garden.

Positives about buckwheat include that it matures quickly, is easily seeded by broadcasting, is relatively inexpensive to purchase by seed, is not “fussy” about where it grows, and germinates quickly. It does not mind low-pH soils and can even out-compete weeds! It has shallow roots and is easily terminated — so planting a new crop after it is no problem — or, if it is still growing in the fall of the year, a frost will kill it. Lastly, it is a wonderful nectar and pollen source for a wide variety of insects. 

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Non-Native Plants Support Non-Native Mosquitoes

It is a common misconception that all mosquitoes feed on blood. Unlike ticks, which require a bloodmeal to progress from one life stage to the next, mosquitoes largely rely on plants throughout their life cycle. Only adult female mosquitoes bloodfeed in order to acquire protein to lay eggs; otherwise, adult mosquitoes feed on plant sugars to gain energy for flying, mating, and metabolic demands. Once those eggs are laid in standing water, mosquitoes hatch as aquatic larvae that eat microbes supported by decaying organic matter, called detritus. This detritus often comprises plant parts like leaves, seeds, and fruits that fall from nearby vegetation into larval habitat. The next life stage before adulthood, the pupa, is non-feeding, so the amount and quality of detritus mosquitoes receive as larvae are crucial. Just like we tell children to drink their milk to grow up to be big and strong, mosquito larvae with plentiful and nutritious resources can reach adulthood faster, grow larger, live longer, and lay more eggs as adults. Yikes! 

life cycle of a Aedes mosquito from adult to egg to larva to pupa
Aedes mosquito life cycle.
Image credit: Centers for Disease Control and Prevention

Leaves may vary drastically in their chemical composition, affecting which microbes they support, how quickly they decay, and what beneficial nutrients or toxic secondary metabolites they release as they decompose. Researchers are still working to identify important traits in a detritus resource base, but a trend has emerged: non-native plants seem to support non-native mosquito populations better than native plants do.

Native species, whether plant, animal, or microbe, are those that occur naturally in the region where they evolved. Over the course of time, these species have adapted to the local environment and developed relationships with other native species. Conversely, non-native species are those which evolved in a different region from that in which they can now be found. A small percent of non-native species establish and spread rapidly throughout their new home, with the potential to harm human well-being, environmental health, and/or economic prosperity. Some researchers speculate that non-native species share certain traits that make them successful invaders. The Asian tiger mosquito, Aedes albopictus, is one of the most successful invaders of the past century, arriving in Texas from Asia in 1985 and reaching us here in Maryland by 1987. The tiger mosquito is capable of spreading viruses such as dengue, West Nile, and zika; it is also a nuisance vector, driving people indoors with its aggressive daytime biting behavior. 

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Moths in the Landscape

 The best kind of green thumb…a perch for a Luna Moth. Photo: M. Talabac

Q:  I found a huge green moth on my front door! What is it, and do they visit flowers so I can attract more?

A:  This beauty is one of my favorite insects…a Luna Moth, a native species and one of our largest North American moths. Their green color, rare among our local moths and butterflies, ranges from medium to pale celery-green or a pistachio ice cream hue. Their long hindwing tails and eyespots combine to give them a look resembling an elephant’s face. I imagine those eyes give foraging birds a moment’s pause, though the bigger predator for these moths is probably bats since they are night-flying.

Adults have vestigial mouthparts and cannot feed, so flowers won’t attract them. They rely on body fat stored from the caterpillar stage (which grows gleefully big) to fuel their brief search for mates and egg-laying sites. You can support breeding populations by caring for caterpillar host plants, which for Luna include hickory, walnut, sweet gum, and white oak, among other trees.

Avoiding pesticide use in home landscapes is of critical importance, though communities that are subjected to aerial forest sprays for Spongy Moth or other pests may, unfortunately, experience population declines, even though such treatments are relatively targeted. Gardeners attempting to rid a tree of nuisance aphids, Spotted Lanternfly, scale, and other insects could inadvertently affect harmless species like these moths in the process. Remember that any tree roots infiltrating a lawn that is treated with a systemic insecticide (like for grubs) might absorb some of those chemicals and transport them into the canopy.

Light pollution is another big detriment to these and many night-active insects (like fireflies), with home landscape accent lighting, porch lights, street lights, and other sources of illumination interfering with their ability to navigate at night.

For anyone curious about moths, I encourage you to participate in or follow National Moth Week, a citizen science project taking place the last full week of July each year. Check out what visits your porch lights, flowers (there are some day-flying nectar-feeding moths), and see if you can ID the caterpillars that wander the landscape or chew holes in tree, shrub, or perennial leaves. So few are truly pests so you won’t need to worry about managing them; leave them to fulfill their part in the food web of our local ecosystem.

You can also sign up to learn about nighttime pollinators and how to support them in the upcoming free webinar: “Working the Night Shift: Pollination After Dark,” taking place on August 3 from noon to 1:30 pm.

By Miri Talabac, Horticulturist, University of Maryland Extension Home & Garden Information Center. Miri writes the Garden Q&A for The Baltimore Sun and Washington Gardener Magazine. Read more by Miri.

Have a plant or insect question? The University of Maryland Extension has answers! Send your questions and photos to Ask ExtensionOur horticulturists are available to answer your questions online, year-round.

Vegetable Problems Update

Wildfire smoke

Persistent wildfire smoke is new for Maryland gardeners. Experts seem to agree that smoke and ash do not pose a health risk for garden produce. Smoke diffuses sunlight but will probably not significantly reduce the total amount of light for photosynthesis. We have not heard/seen any reports of gardeners picking up smoky flavors in harvested greens or other vegetables or fruits.

  • Wash all produce prior to eating it raw or cooking with it
  • Wear an N-95 quality mask when working outside on days when wildfire smoke worsens air quality
  • Hose off plants if a noticeable soot layer develops from prolonged, intense smoke

Wildfire smoke has been shown to boost the levels of ozone and other air pollutants which can injure plants. Watermelon, squash, pumpkin, beans, and potato are especially vulnerable to high ozone levels (above 75 ppb).

Drought and damaging storms

Wildfire smoke interfered with weather patterns and likely contributed to cooler and drier weather across much of the state. 

Mid-May through June:

  • Lower average temperatures
  • 75% of state in moderate drought on July 3rd
  • Slow start for warm-season crops


  • High heat and humidity
  • Spotty rainfall
  • Insect and disease issues increasing
Maryland drought status map
The Maryland Department of the Environment announced a Drought Watch on July 10, encouraging voluntary reduction in residential water use.
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An Ode to Beebalms, Our Beautiful Biodiversity Magnets

Scarlet beebalm (Monarda didyma). Photo: A. Espíndola

Among the many native plants of North America, there’s one that every summer stuns me with its beauty and its important role in our ecosystems and our lives. In today’s post, I want to share some information about a lovely group of plants local to right here, which can be easily grown in our green spaces, and which one can observe flowering right now: beebalms!

What are beebalms?

Beebalms are a group of plants in the mint family (Lamiaceae) that belong to the genus Monarda. This genus is restricted to North America and includes several species. In Maryland, there are at least four species present, one of which (M. clinopodia, the basil beebalm) is currently listed as requiring conservation actions (listed as Vulnerable). The other three species (M. didyma, M. fistulosa, M. punctata) appear to be relatively common in the region and are easy to grow in our green spaces. All species reach about 2 to 5 feet in height and are great additions to flower beds because of their beauty but also because they act as biodiversity magnets. For example, the genus Monarda has been recognized as supporting at least three rare and specialist bee species in the Eastern USA, and attracting a lot of natural enemies of pests, meaning that providing these floral resources can support the populations of bee species that depend on the pollen of these plants for their nutrition and help us naturally control pests in our green spaces. And last but not least, later in the season their fruits support birds and, if left uncut, their stems offer overwintering spaces for arthropods.

Scarlet beebalm (M. didyma)

This is a perennial species with dark red flowers that bloom during the summer. As for all beebalms, the flower heads are formed by many elongated flowers that harbor abundant nectar. The plant is incredibly attractive to pollinators, acting as a magnet to bees of all sizes, butterflies, and hummingbirds. Besides its great support to pollinators and other arthropods, this species (along with M. fistulosa) has medicinal properties, which have been identified and used since immemorable times by Native Americans. The very name of beebalm is even related to these uses, since the plant can be used to produce poultices that help with skin affections, including bee stings. Preparations of the plant are also traditionally used to help with digestive and respiratory issues. Finally, as for many mint plants, this species is rich in essential oils, which makes it a good one to flavor foods like one would do with oregano and mint. You can learn more about how to grow this species, along with other facts on this USDA information sheet.

a stand of brightly colored red flowers - monarda didyma

Scarlet beebalms display red flower heads that offer abundant nectar to a large variety of vertebrate and invertebrate pollinators. Photos: A. Espíndola, J. Schneid (CC)

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Ants & Termites: The Garden Thyme Podcast

In this month’s episode of The Garden Thyme Podcast, we are talking about two common household pests: ants and termites. We often get questions about these two pests. While both live in colonies and can enter our homes, they have very different lifecycles and social structures. Some of them are nuisance pests, while others can cause damage to our homes.

We also have our: 

  • Native Plant of the Month – Wild mint (Mentha arvensis)– ~ 24:25
  • Bug of the Month –  Golden-backed snipe fly ~ ~28:30
  • Garden Tips of the Month – ~31:30

If you have any garden-related questions, please email us at or look us up on Facebook. For more information about these topics, please check out the Home and Garden Information Center.

The Garden Thyme Podcast is brought to you by the University of Maryland Extension. Hosts are Mikaela Boley, Senior Agent Associate (Talbot County) for Horticulture; Rachel Rhodes, Agent Associate for Horticulture (Queen Anne’s County); and Emily Zobel, Senior Agent Associate for Agriculture (Dorchester County).

Theme Song: By Jason Inc