Pollinators – Maryland Grows

Natives vs. non-natives – good or bad for pollinators?

October 20, 2026October 20, 2026Maryland GrowsLeave a comment

A large olive green and dark orange moth with fast beating hummingbird type wings using its proboscis to feed on a pueple flower. — *Native pollinator, Clearwing Hummingbird Moth, visiting non-native Verbena bonariensis, Purpletop vervain.* *Photo: M. Talabac, UMD Extension*

As a biologist who works on pollination, two of the top questions I receive on a regular basis are what to plant to support pollinators, and whether non-natives are bad for pollinators. Although I can state a number of relatively easy-to-grow plants that are both good for supporting pollinators in our area (past blog articles: Want flowers next year? Pollinator plants to plant this fall, What should I plant to help pollinators? and Helping pollinators in small green spaces are some ideas), it is really hard to give a hard answer based on research knowledge to the second question. In today’s article, I decided to try to explain why this is so, and still try to answer that question. Spoiler alert: my answer is basically an “it depends” with some big caveats. Keep reading to see what I mean.

Concepts meet reality

One of the characteristics of scientific knowledge is that it accumulates, and that knowledge we collect can eventually be used to make predictions about what one may expect to observe under new conditions. These predictions are of course not necessarily correct all the time, but their accuracy is expected to increase with the amount of knowledge that we have about the processes we are seeking to predict. As a scientific field, biology has indeed accumulated a lot of knowledge, which allows us to make some pretty logical predictions about the potential effect of non-native plants on pollinators. Let’s go over some of those predictions.

As I mentioned in a previous post, “What are local ecotype plants and why do they matter to pollinators?“, the interactions we observe today between plants and their pollinators are the result of millions of years of (co)evolution, which has modulated the “matching” of needs of the two parts of the interaction. This means that evolution led to species that interact to be generally well-adapted to each other. For example, species that have been interacting for a long time at a given place (as is the case of species that are native to a place) tend to temporally match better with each other; bees that use certain plants tend to be active when those plants flower, and plants that need certain bees tend to flower when those bees are active. This means that it is plausible that if those plants or bees are not available at a certain time point, they will not be able to survive properly because their needed partner is not around. In the context of exotic plants, it is possible that the fact that they are exotic makes them poor pollinator plants, since they are more likely to not be “attuned” to the temporal needs of the local species.

A black white and yellow striped caterpillar feeding on the leaves of a plant with slender leaves and orange clustered flowers. — *Native Monarach butterfly caterpillar feeding on Aesclepias tuberosa, Butterfly weed, one of the milkdweed host plants. Photo: Crista Carignan, UMD Extension*

From a different perspective, plants and pollinators have an interaction that is based on the consumption of floral rewards (pollen, nectar, etc.) by the pollinator (and in some cases, such as that of moths and butterflies, the consumption of other plant tissue in their larval stages). Those rewards, however, are not chemically identical across plants, meaning that each plant species, genus or family will tend to have rewards that contain chemical compounds specific to them, and to which the pollinators that consume them are adapted, leading to different levels of specialization. The practical consequence of this is that not all pollinators visit all plants, but rather that certain pollinators will only visit the plants that offer rewards they can physiologically consume and digest. These adaptations to deal with certain chemical compounds evolve over a long time, meaning that it is more likely that species native to the same area will be able to effectively display them, simply because those species have been exposed to those compounds for longer and are thus more likely to be adapted to them.

Given all of this knowledge, it is expected that species that have been evolving with each other over long periods of time – such as species native to the same region – would also be more beneficial to the pollination partners than species that are not native to the same region. And indeed, there are some studies that show that some non-native plant species are not chemically or temporally accessible to some bee species, leading to certain bee species avoiding them altogether because they cannot manage the chemical compounds they carry. That said, those studies are rarely counted, not because people do not want to take them on, but because testing such ideas on many species across the world requires a lot of funding, time, access to appropriate sites, and technical skill… all of which makes the studies extremely hard to run.

So, are non-natives good or bad for pollinators?

Despite the large technical, financial and logistical complexities of testing the points I noted above specifically, some studies have tried to evaluate the effect of non-natives on pollination interactions and the parts involved through the study of spaces that already carry different levels of natives and non-natives. These studies confirm some of the predictions but also bring a more nuanced light to the topic… which points to the need for more studies and my “it depends” type of answer to the question. So, let me tell you what these studies tend to show.

A relevant study on this is one in which gardens that had different levels of ground cover by native and non-native species were studied in terms of their floral visitation. In that study, they measured A LOT of gardens and followed floral visitation of all the plants present throughout a whole season. What they saw was that generally pollinators tended to be more abundant when most natives were flowering, but that later in the season non-natives could provide resources to pollinators that were still around but had no native plants to visit, because those were not flowering anymore (or not yet). Based on that study, one would suggest that planting natives is indeed good (that leads to the most visits by pollinators) but that displaying non-natives that flower later in the season (especially when natives that flower at that time of the season are not available) can help support some pollinators during those times because they compensate for the lack of native floral resources available to pollinators. This said, that study was geographically restricted (a small region of Germany), included only urban gardens, could not manipulate the composition of the plant choice (this was on gardens that were already established based on the homeowners’ choices) and was done through one season only. The authors also recognized that many times the non-natives were of the same family of a native plant, meaning that perhaps the pollinators were already slightly pre-adapted to their chemistries, and that the results would thus be different if no native related plants had been present. Also, they warned about the use of non-natives that could have potential for invasiveness. (Exotic garden plants partly substitute for native plants as resources for pollinators when native plants become seasonally scarce)

Only a few studies were done after this one, but they found slightly different results. For example, a study done on flower plantings in Paris over two seasons found that native plants indeed support more diverse, abundant, and specialized pollination interactions, but that the non-natives used in those sites appeared to support more generalist interactions than the native species. This would suggest that native plants appear to be positioned particularly well to increase pollinator diversity and to support *specialized* pollinators that would otherwise not be supported at all by the non-native plants.

Finally, another study (from the USA) that looked not so much at the plants but at the pollinators, found that non-native non-honeybee bees tended to clearly prefer non-native plants over natives, meaning that those plants would tend to provide support especially to non-native bees, and thus appear to assist in some ways the survival of non-native bees that are in some cases competing for resources and displacing native bee species. (Native and exotic plants play different roles in urban pollination networks across seasons)

This is complicated! What do I do with this information?

Generally, I would interpret all of this as pointing to:

Native plants should be preferred when possible because they do indeed support larger and more complex sets of pollination interactions.
If they are non-invasive, one can maybe consider planting non-natives, especially if plants of the same family or genus are already native to the region. However, it is always important to ask oneself why one wants to absolutely do this.
Non-natives can help support pollinators during the “summer dearth”, when few natives are available… although one can also try to increase the frequency of natives that do flower during those times.

By Anahí Espíndola, Associate Professor, Department of Entomology, University of Maryland, College Park. See more posts by Anahí.

Anahí also writes an Extension Blog in Spanish! Check it out here, extensionesp.umd.edu, and please share and spread the word to your Spanish-speaking friends and colleagues in Maryland. ¡Bienvenidos a Extensión en Español!

Meet the Smoky-winged Beetle Bandit Wasp (Cerceris fumipennis)

August 14, 2026August 13, 2026Stacy Small-Lorenz1 Comment

Closeup of fingers holding a mostly black wasp with one yellow band on its abdomen and brown transparent wings splayed. — *Smoky-winged Beetle Bandit Wasp* *Photo by: (c) hoops146, iNaturalist*,*(CC BY-NC) some rights reserved*

I was transplanting a few Blue Mistflower (Conoclinium coelestinum) plants into my drainage swale pollinator garden last weekend when I noticed this new insect visitor to my blooming Rattlesnake Masters (Eringium yuccifolium; below).

Spikey whiteish green flowers of Rattlesnake Master with a visiting Smoky-winged Beetle Bandit Wasp. — *A Smoky-winged Beetle Bandit Wasp nectars on a Rattlesnake Master flower in the author’s pollinator garden.* Photo: Stacy Small-Lorenz, UME

This gentle beauty has a name that could have been penned by a cowboy poet – Smoky-winged Beetle Bandit Wasp (Cerceris fumipennis; Family Crabronidae) – and it plays an important ecological role. It parasitizes adult metallic wood-boring beetles of the family Buprestidae, including oak-boring beetles and the Emerald Ash Borer (Agrilus planipennis), an invasive beetle that is devastating North American ash trees, especially Green and White Ashes (Fraxinus pennsylvanica and americana).

The Smoky-winged Beetle Bandit Wasp is native to Eastern North America and is the only North American wasp known to parasitize adults of Buprestid wood-boring tree pests, using the beetle bodies as hosts for their eggs and larvae. Scientists have even used this species for biosurveillance to monitor range expansion of the Emerald Ash Borer.

A combination of traits can help identify this native parasitoid wasp. Look for its black head, thorax, and abdomen and smoky-brown wings. Females may have a blue reflection to their wings. A distinctive cream or white apical band on the second abdominal segment is another key characteristic. Females have three cream-colored spots on the face, while males have two yellow triangles between their eyes.

Smoky-winged Beetle Bandit Wasp adults are active mid-June into September in the northern part of their range. They are solitary ground-nesters that generally produce two generations annually. According to Heather Holm (2021), they usually burrow into compacted sandy or gravelly soil along rivers, in paths, gravel parking lots, or even baseball diamonds, frequently near forests where they can hunt for their beetle victims in the tree canopy, then bring them back to the nest. A female captures and injects a beetle with venom, then carries it in her mandibles to stash with several other paralyzed beetles in an underground nest chamber.

The wasp carrying 2 shiny green matalic emerald ash borer beetle on a blue paper with a hole covering her nest opening. on sandy ground. There is a white golf tee holding the paper down. — A female Smoky-winged Beetle Bandit wasp brings a pair of mating Emerald Ash Borer Beetles back to her nest. The blue paper shown here will make it difficult for her to bring her victims into the nest, allowing biologists to collect the beetle bodies for pest monitoring. Photo: Philip Careless, Wikimedia Commons [CC BY-SA 3.0]

She’ll lay one egg on the top beetle that hatches after several days. She provides a larger supply of beetles for her female offspring than for the males. After hatching, her larvae will remain in their underground chambers over winter, feasting on beetles from their own personal stockpiles, before emerging as adults the following summer.

Biologists can observe the beetles that female wasps bring back to their ground burrows to document the presence of these tree pests.

These beneficial wasps are also “accidental” pollinators that pick up pollen on their bodies and transport it to other flowers while nectaring. They are harmless to humans and defenders of our forests, so two things we can do for them in return are protecting their nest burrows when we find them and providing some of their preferred nectar plants in a sunny spot near the forest, like rattlesnake master, swamp or butterfly milkweed (Asclepias incarnata or tuberosa), Virginia mountain mint (Pycanthemum viginianum), daisy fleabane (Erigeron strigosus) and Canada goldenrod (Solidago canadensis). These are relatively simple pest management practices for forest conservation that will also benefit many other pollinators.

While one species of wasp alone may not entirely solve the widespread dilemma of invasive wood-boring tree pests, there are other introduced and native parasitoid wasp species and woodpeckers that target earlier stages of the Emerald Ash Borer life cycle (egg and larval) (Shrewsbury 2026). Therefore, working in combination with other species, they could make a real difference for the next forest generation and therefore deserve our conservation attention.

By Stacy Small-Lorenz, UME Residential Landscape Ecology Specialist

This article was originally published in the UME IPM Weekly Report on August 7, 2026

References:

Holm, H. 2021. Wasps: Their Biology, Diversity, and Role as Beneficial Insects and Pollinators of Native Plants. Pollination Press LLC. Minnesota, USA. 420 pp.

Shrewsbury, P. 2026. The Exciting Life of Parasitoids and Their Role as Biological Control Agents. Presented at the Stanton A. Gill Symposium: A Focus on Biological Control. August 5, 2026. University of Maryland Extension, Clarksville, MD.

Why don’t I see pollinators on my plants?

July 17, 2026Maryland GrowsLeave a comment

One of the most widespread actions implemented to support pollinators and other beneficial organisms is the planting of (native) flowering plants. The idea is that if we offer food to pollinators, they will come. However, we may have planted the plants, but the pollinators still aren’t coming. What could be happening? In this post, I will cover some biological reasons why this may be happening, and some solutions to consider.

Not all flowers are made equal

To a pollinator’s eye, not all flowers are the same. As we mentioned in other posts, each pollinator group (e.g., butterflies, birds, bees, flies…) has a different shape and different sensorial and physical abilities. While a butterfly may be able to reach the nectar at the bottom of a very tubular and long flower, a fly may not. Likewise, a large pollinator that is physically stronger than a small pollinator may be able to enter a very closed flower. Further, a night pollinator can obtain nectar from plants that offer it at night, while it will not get anything from those that offer it during the day…. I guess you see my point. Essentially, pollinators prefer flowers that make it easiest to locate and harvest resources like nectar and pollen. These differences mean that unless those flowers are present in a landscape, certain groups of pollinators may not be seen at all.

A grid of 9 flowers in various shapes and colors and different pollinators from bees and wasps, to moths and birds. — *Different floral shapes and colors make floral rewards more easily accessible to different pollinators. Photos: J. of Pollination Ecology.*

Not all flowers necessarily offer what a pollinator is after

Pollinators visit flowers to obtain something they need. That something may be food (e.g., nectar, pollen, parts of the flower), materials for reproduction (e.g., perfumes), materials for nest building (e.g., resins, floral oils), or simply a place to overnight, stay warm, and/or mate. As a matter of fact, not every single flower serves all those needs, making the pollinators end up “sorting themselves” among the plants that offer what they need.

A yellow blooming flower cluster with a bee climbing inside one of the blooms. — *A bee of the genus Chalepogenus visiting a flower of Calceolaria dentata (native to Chile and Argentina) to collect floral oils and pollen. Photo: A. Espíndola.*

Let me give you an example. In my research life, I work on a specialized pollination system that involves flowers that do not offer nectar at all, but instead offer floral oils (and pollen) in exchange for pollination (you can read more about this from the blog post: Why Do Pollinators Visit Flowers?, May ’20). These flowers are called lady slippers and belong to the Pan-American genus Calceolaria. When we observe which pollinators visit the flowers, we see that it is mostly bees who specialize in collecting floral oils (in our case, bees of the genera Centris and Chalepogenus), and basically nothing else. In landscaping, filling our yards with only one specialized flower type drastically limits pollinator diversity. For instance, if we only planted oil-producing flowers, we would not see many diverse pollinators. This highlights a key rule: the rewards a plant offers dictate the visitors it attracts. Just as varied flower shapes are crucial, providing a diverse mix of nutritional rewards—like nectar, pollen, and oils—is the best way to boost the number and variety of pollinators in our green spaces. As for the floral shape I was referring to, planting species that offer different types of rewards is a very good way to increase the number and types of pollinators we see in our green spaces.

The flowers do not necessarily want to share too much

Plants attract pollinators because they can get pollination from them, which allows the plant to reproduce. From a biological point of view, a pollinator will be a good one if it carries pollen from the stamens of a flower and makes it land on the stigma, so it can germinate and then fertilize the ovules. This is all good and nice; the problem, however, is that many pollinators use pollen as food. This creates a conflict between the plant’s and the pollinator’s interests: a plant needs the pollen (that contains its sperm) to not be eaten but to fertilize its ovules, but many pollinators just want to eat the pollen (and they have good reason for this, since a pollen grain is extremely rich in nutrients!).

A black and white microscope image of pollen grains. Some are spikey, some round, and some beanshaped with cantelope rind-looking texture. — *Pollen grains have different structures and shapes. Photo: Dartmouth College Electron Microscope Facility.*

As a response to this conflict, some strategies have evolved that somewhat “control” the feeding on pollen that pollinators may do. In fact, plants protect their pollen with physical structures that make it hard to be broken by pollinators. Some of these pollen grains feature spikes and thickened walls, which force pollinators to use specialized tools to break through them. Along with this physical “shield”, pollen grains often contain what are called **secondary metabolites.** These are chemical compounds that make the pollen indigestible or toxic, unless the organism trying to eat it has evolved ways to tolerate those compounds themselves. Closely related plants produce similar chemical compounds; the unique chemistry of a plant family dictates which pollinators can digest its pollen. This leads to different levels of floral specialization on the side of the pollinators. Pollinators will only try to visit plants that offer pollen they can digest, which again, restricts the flowers they visit. As for the previous points, increasing the different types of plants by having representatives of different plant families can increase the variety in the chemical quality of the pollen offered, attracting and supporting different types of more or less specialized pollinators.

By Anahí Espíndola, Assistant Professor, Department of Entomology, University of Maryland, College Park. See more posts by Anahí.

Small but mighty. The amazing ground-nesting bee!

June 19, 2026Maryland GrowsLeave a comment

The summer is almost here, and if you are like me, you have already been outside and seen a bunch of tiny bees digging, digging, digging, and buzzing around flowers. Who are these little ladies? And what on earth (pun intended) are they doing? In today’s blog, I want to explain a bit about these super powerhouses, how they do what they do, and point to some of these cool bees that we can find right here in Maryland and our general region.

What are ground-nesting bees?

As its name indicates, ground-nesting bees are bees that nest in the ground, mostly by digging their nests. Ground-nesting bees are found in several families of bees, and being a soil nester/digger is actually one of the most common nesting strategies among solitary bees. In these bees, once the female finds a good nesting site, she starts excavating it to create an underground nest, which often has several brood cells, in which the larvae develop. These nests are usually found in spaces where the vegetation is sparse or the soil bare, and can sometimes be built along with other nests of the same species, leading to communal nesting areas. It is because of this preference for relatively open ground that it is often recommended that at least some uncovered ground is left in our green spaces, which helps provide habitat for their establishment.

A tiny bee is seen crawling out of a mound of soil on the ground. — *Ground-nesting bee coming out of her nest. Photo: Colleen (CC0).*

How do ground nesters build their nests?

As good miners or soil diggers, ground-nesting bees also have specific behavioral and morphological traits that make them good at what they do. Bees that excavate have modified leg structures that allow them to easily move within tunnels, strong mandibles that they use to actually dig the cavity, and modified extremities of the abdomen (the pygidial plate) that function as sorts of trowels and allow them to pack soil on the walls of the cavity they are digging.

Along with having the right tools of the trade, these bees are also selective of the type of soil they use to build their nests. Most ground-nesting bees prefer soils that are not too compacted, with at least some sand content, which makes them easier to dig through. This means that it is more likely that we will find these bees in rockier/sandier soils than in super clay-y ones. As a matter of fact, many ground-nesting bees are associated with dune nesting, and because dunes are often endangered habitats (because they are often disturbed/destroyed by human activities), many sand-nesting specialists end up becoming endangered as well. And as a fun fact about soil choice, bee experts think that because finding “good soil” is so important for the survival of these bees, bees tend to become associated with specific spots for nesting, with the nesting site becoming a sort of “family place”, where several generations of females from the same family line come back to nest over the years/generations.

A close up of the pygidial plant which is a small darker triangular structure at the tip of the bee's abdomen. — *The pygidial plate is a structure present at the tip of the abdomen of ground-nesting bees that functions as a trowel. Photo: MN Native Bees.*

Because digging through the soil with their mandibles (and sometimes their legs) is hard work, bees usually tend to choose the best timing to start their digging. In fact, the hardest part of the soil to dig through for a bee is the surface, which is often the most compacted. For this reason, bees tend to start digging after the soil has become moist (e.g., after rains). Incredibly, some ground-digging bees are even able to add, if needed, secretions or even nectar to humidify and loosen the soil! Once the bee has started her excavation, she continues digging deeper and bringing soil out of the construction area, which leads to all sorts of “mounts” being built around the nest entrance and sometimes chimney-looking structures.

What are some ground nesters from Maryland?

Andrena vicina – The neighborly mining bee

a close up of a bee gathering pollen from white flowers — *Andrena vicina.* *Photo: K. P. McFarland (CC0).*

This Andreniid is relatively large (about 1- 1.5 cm), present in North America and common in the Eastern USA. This species received that cute name because it is one of those that builds communal nesting areas (“neighborhoods”). In Maryland, the species is active right now (~June/July) and is generally seen visiting many native plants and crops. In particular, this is one of the known visitors of, among other plants, Rhododendron and Azaleas, several heather family plants (like Vaccinium, Kalmia), as well as several rose family plants (Prunus, Rubus).

Augochlorella aurata – Golden sweat bee

a tiny metallic green sweat beed in the center of a yellow flower

Augochlorella aurata. Photo: C. Martin (CC0).

This is a species in the Halictid family, and is called a sweat bee because it is often found collecting sweat (for water and salts). This is one of those tiny bees that you may find landing on you on a hot day, really committed to not letting go of your skin! This particular bee is relatively easy to recognize because it is small, metallic-looking, with beautiful green/golden iridescence. This bee is not fully solitary and is a species recognized to display primitive eusociality (for example, honey bees are true eusocials). In this species, there is a queen that starts a nest, and across the season, generations of first infertile and later fertile workers are produced. By the end of the season, the fertile workers are inseminated and disperse to overwinter. This bee species is pretty generalist in its choice of plants, known as a pollinator of many crops (e.g., apples, tomatoes, watermelon) as well as native plants.

Enhance Biodiversity in Your Vegetable Garden by Planting More Flowers!

May 28, 2026Maryland GrowsLeave a comment

A view of a fenced in vegetable garden with Salad tables in the forground and multiple raised garden beds full of various vegetables. Bright orange marigold flowers line the edges of the raised beds and there are wood chip paths inbetween the planting areas. — *Marigolds line the edges of raised garden beds, bursting with vegetables in this county extension demonstration garden. Photo: Jon Traunfeld*

A practice generally used in agricultural contexts is that of floral supplementation. In today’s blog, I would like to dig a bit into this idea and present some strategies to implement it at smaller scales, like small vegetable gardens and green spaces. Read along to learn a bit more!

What is floral supplementation?

Agriculture using western methods generally leads to losses of plant biodiversity in and around fields, mostly because it transforms diverse spaces into large monocultures (the crop fields). This, in turn, reduces the ability of the ecosystem to regulate pests, maintain pollination and eventually can negatively affect yield and production, along with increasing environmental erosion. As a response to these needs, strategies have been developed to increase biodiversity in agricultural contexts, and one of those is floral supplementation. In this strategy, the areas surrounding the crop fields are planted with diverse floral mixes or hedges, or the crop rows are intercropped with flowering plants. Such approaches improve soil quality and reduce erosion, increase diversity of plants and animals associated with them, and in many cases lead to improved pest control and pollination of the crop. Although this is a practice more or less widespread and recognized for production fields, it is not often officially promoted in smaller areas such as gardens or the green spaces that surround them. Let’s fix that! 😊

Why does floral supplementation work?

The idea behind these practices is that they increase the spatial and plant resources available to the local biotic community. By increasing the number of plant species present in an area, the different types of food and nesting resources are also increased and become more complex. For example, there may be flowers that bloom at different times of the season, that produce different types of nectar and can support different pollinators, fruits that support different insects and birds, plants of different heights and structure that can offer shelter to different organisms. These modifications eventually lead to more diverse animal communities being present in the area where the supplements are added. From the point of view of the benefits of these changes on the actual performance of the crop field, this diversity promotes the presence of biological control of pest agents (e.g., predators of pests, parasitoids), as well as increases the diversity and abundance of potential pollinating species. The presence of a more robust plant community can also promote soil retention through the presence of more roots to physically retain it, reducing erosion and water runoff.

Tomato plants with green tomatoes growing in a raised garden bed with a railing in the background. Interspersed plantings include basil, and chard. — *A way to implement floral supplementation in small spaces is through the combination of different crops on the same pace, such as offered by the idea of companion plantings. Photo: Steph L.*

Floral supplementation in gardens

Although the extent of floral supplementation done at the agricultural scale can not be reproduced at the garden level, the same principles can be implemented, especially if the gardening space is not necessarily embedded in a very biodiverse context. Here are some ideas on how to do it.

Intercropping and Companion Planting

A cool way to both increase diversity and production per unit of area is the use of intercropping with companion plantings. Here, different crops can be interplanted, with rows alternating species, or with several crop species planted in a mixed way in the same part of the garden. This relates to the idea of companion planting, where species that are planted together are selected for their ability to successfully coexist and support each other. The table gives some ideas on potential combinations to promote and avoid.

Companion planting promotes the interplanting of different crops/herbs, with species known to be compatible and incompatible in these plantings. Table from Virginia Cooperative Extension publication, Companion Planting in Gardening

Hedgerows

Green bushes with pink flowers along a grassy area under trees. — *Especially if planted with native species, hedgerows can offer a complex structure for a lot of animal diversity to establish close to our gardens. Photo: M. Gimber.*

This strategy can be especially effective if there is a lot of room around the garden plot. Instead of leaving that as a mowed space, it is possible to turn it into a structurally and species-diverse space! For this, one can consider planting sets of native shrubs/small trees that can provide complex shelter spaces and flower/fruit/seed resources for many animals (including humans! 😛 ). Some choices I really like for our area are fringe trees, spicebushes, witch hazels, hazels, pawpaws, serviceberries, native elderberries, or redbuds. Of course, not all these species are appropriate for all areas, so depending on the level of light and soil conditions, some may be preferred over others.

Flower Strips

A close up of Monarda or beebalm with red blooms — Even when not much space is available, the planting of native herbaceous plants can lead to an important bump in diversity around our vegetable gardens. This strip of *Monarda, Solidago, Penstemon, Rudbecia* and some other native plants is directly adjacent to my vegetable garden and attracts many pollinators and predators such as wasps and mantids. Photo: A. Espindola.

Flower strips are also a great choice, and if space is available, one can easily turn them into a small floral meadow. These spaces can be planted with seed mixes, which can be purchased from seed companies specialized in the establishment of native meadows. (Be sure to review the species list since some meadow mixes can contain invasive or borderline invasive plants, others may contain annuals like Cosmos.) If the space available is not very large, it may be more practical to just plant a set of native flowers that bloom at different times through the season. Check out this other post where I direct people to some specific plant lists that can be handy for our area. Especially if the species chosen are perennial, the planting will lead to a long term establishment, and if wanted, new plants can be added over the years, as some species become more established.

Book Review: The Nature of Oaks

January 15, 2025January 15, 2025Maryland GrowsLeave a comment

Winter’s leafless landscapes, while beautiful in their own right, can look barren compared to the cacophony of color and activity of late spring/early summer. Once an oak’s leaves have senesced and its acorns have fallen, you’d think that not much is happening way up there in the canopy. But surprisingly there is! Tallamy’s The Nature of Oaks, takes the reader on a month by month journey of how these mighty trees support an abundance of life year round.

In fact, indigenous oaks (genus Quercus) support the highest number of Lepidoptera (butterflies, moths, and skippers) species in the mid-Atlantic region- some 534 different native species (Tallamy & Shropshire, 2009). Lepidoptera in the larva or caterpillar stage, such as the Greater Oak Dagger Moth (Acronicta lobeliae) (Fig. 1), often have a narrow diet breadth feeding on only a single family of plants. The over 500 species of caterpillars that oaks support, in turn, feed birds and other wildlife further up the food chain.

Fig. 1. Greater Oak Dagger Moth caterpillar. Photo: Nick Furlan

Tallamy’s Nature of Oaks gives numerous examples of insects’ impressive camouflaging, and describes how it helps them go undetected by hungry birds. For instance, the oak specialist American Oak Beauty (Phaeoura quernaria) blends in amazingly well with its host plant during both its larval and adult stages (Figs. 2 & 3). It’s no wonder that we often don’t notice all of the activity on oaks, especially given that much of it takes place at night.

Photo of an American Oak Beauty caterpillar on a tree twig. The caterpillar looks very much like the tree twig. — Fig. 2. American Oak Beauty caterpillar. Photo credit: Adrian Romo

Photo of an American Oak Beauty moth on the bark of an oak tree. The bark is covered with gray and green colored lichens. The moth's body colors and color pattern make it difficult to see the outline and shape of the moth. — Fig. 3. American Oak Beauty moth. Photo credit: Basil Conlin

Tallamy also considers what’s going on beneath the canopy. Many oak-dependent species complete their life cycle in either the leaf litter or soil at the base of the tree. Research by our state entomologist and UMD alum Max Ferlauto shows that raking less results in more butterflies, moths, and beneficial arthropods. The harmful effects of leaf removal are widespread, impacting community composition, nutrient cycling, and soil stability (Fig. 4).

Illustration showing the negative effects of removing leaves from the ground. — Fig. 4. Negative effects of leaf removal. Illustration by Maggie Lin

Of course oaks support a host of other arthropods and critters- from tiny wasps that form galls on oak leaves and terminal buds to numerous birds and mammals that depend on the trees’ nutrient rich acorns. Tallamy’s Nature of Oaks contains compelling data and entertaining anecdotes that left me awestruck by the beauty and interconnectedness of these mighty trees with all living things. Tallamy suggests if you can only plant one tree, make it an oak.

If you’re feeling inspired to plant an oak in your yard, Tallamy provides guidance on where and how to plant oaks for long term success. For instance, to overcome the concern of tree damage, he suggests planting young trees closer together (vs a specimen tree) so that they’ll be smaller in diameter and their roots will interlock. In Maryland, we’ve 21 native oak species that are commercially available, including two that reach a max height of 20 feet. For photos and details on growth requirements, habitat value, etc. see the new Commercial Maryland Native Plant List.

Where can you purchase native oaks (and other plants)? This month, the MD Department of Agriculture (MDA) launched a certification program for wholesalers, growers, and retailers of native plants. The program will make it easier for consumers to find sellers via a tiered system (novice, pro, and premium). Certified sellers will be listed on MDA, MD DNR, and UME’s web sites (coming soon). The program will also help consumers quickly identify which plants are native to MD via a new ‘Best Maryland Native Plant’ logo that retailers are encouraged to use on plant tags and signage.

If you’ve any questions or comments about growing or using oaks or native plants in general, I’d love to hear from you at lkuder@umd.edu.

Reference:

Tallamy, D. W., & Shropshire, K. J. (2009). Ranking lepidopteran use of native versus introduced plants. Conservation Biology, 23(4), 941-947.

By Lisa Kuder, Native Plants and Landscapes Specialist, University of Maryland Extension. See more posts by Lisa.

How to Pay for a Pollinator or Native Plant Garden?

December 9, 2024Maryland GrowsLeave a comment

We hear a lot about the importance of establishing native and pollinator gardens. Indeed, these spaces provide many ecological services, from providing food resources and shelter for biodiversity to improving the quality of our soils and reducing water runoff. However, establishing these spaces requires at least some funds, which may or may not be available to many. In this post, I want to share some resources that can provide either funding or materials to establish such spaces in our properties.

Grants and rebates for native gardens and more

In our region, several grants exist that can provide funding to partially or completely cover expenses associated with the establishment of pollinator and native gardens. Some of these are state- or region-wide, while others are county or city-based. Below I share some of these, but because many of these grants are local, if you don’t happen to be in the regions where these are active, do a quick search on your favorite web search engine and I am pretty sure you’ll find one that applies to you relatively easily.

State-wide grant:

The Chesapeake Bay Trust has a state-wide program of mini grants which can be used to fund pollinator and rain gardens, among others. These grants provide up to $5,000 of funding for projects of different sizes, and the submission deadline is on a rolling basis. Applicants can be many different types of organizations, but it’s best is to check their current guidelines to know all the specifics about each year’s rules (these can be found directly on the grant website).

County-based programs:

Log for Prince George's County. It says Prince George's County Maryland Proud. Get to Know Us.

The Rain Check Rebate Program is offered by Prince George’s County and includes monetary support to establish rain gardens (which can also act as pollinator gardens) and other features (e.g., rain barrels, permeable driveways) that will increase water retention and reduce water runoff. Through this program, private property owners receive up to $6,000, and commercial properties, associations, and non-profits receive up to $20,000. The application process is relatively straightforward and simple, and the reimbursements are processed relatively quickly.

The non-profit Unity Gardens provides grants to fund the planting of native gardens (including rain and pollinator gardens) in Anne Arundel County. These grants are open to the public and range from $1,000 to $3,000 (depending on the type of project). Applications open in the fall and spring, but the documentation and guidelines for applications are accessible all year round. Check the website to learn more.

City-based grants:

The city of Ocean City, MD offers mini-grants for local property owners. These grants aim to support the establishment of pollinator gardens and other native plant gardens within the boundaries of the city. The grants provide up to $5,000 of funding, and applications for some of these projects are open year-round, while others have specific deadlines. Check the grants website to learn the specifics about each of these programs.

Free plants to establish gardens

Not every organization or institution has funds to establish grants such as those presented above. However, many cities and other non-profits give away plants at different times of the year. Generally, these giveaways happen in the spring and the fall, when plantings are the most likely to succeed. Below, I’ve included some examples for you. However, note that many local events happen everywhere, so if you’re interested in these giveaways, I strongly recommend that you search or keep an eye out for announcements in your area by the end of the winter or the summer.

Free native garden kits and plants:

The organization Nature Forward provides free native garden kits which include garden designs and the actual plants that go with them! Because this is directly associated with the Anacostia watershed, the geographical range of this program is restricted (check the map on their website). The sign-up is currently full, but you can still add yourself to the waitlist.

Sometimes, native plant nurseries decide to organize such giveaways. This is the case of Bona Terra in Friendship, MD, which created a “plant grant,” basically a registration-based plant giveaway. The giveaway can be for individuals or groups, and registration is required to receive either individual plants or trays. Check out their website to learn more and access the forms.

City-based plant giveaways:
Several cities provide free plants to their residents. An example is the City of College Park, which has been giving away native plants that support pollinators throughout the year at markets and public events. Check with your city or local government to see if such programs are available to you… and if they are not, you can always ask for them to be established!!