We are still alive! How to protect pollinators in the slow season

Even when they look dry and “dead,” our green spaces are full of life. When we think about plants, for example, we can see that herbaceous perennials seem dry but they are actually just retreating underground, while annuals continue their life cycle by spending the winter as seeds in the ground. The same is true for other organisms that live in our green spaces: squirrels become less active, snakes retreat to sheltered spaces, and insects may overwinter as adults underground or in crevasses or as juveniles in their nests or chrysalises. Among these insects, there is a particular group that we seem to take a lot of effort to protect in season, but that we may then forget about in the fall and winter: our pollinators. In today’s post, I would like to talk about some specific ways that allow us to take care of our green spaces in the fall, all while continuing to support these organisms we worked so hard to support throughout the growing season.

Where are our pollinators in the winter?

As we mentioned in a previous post, pollinators don’t disappear in the winter. Instead, they either migrate to warmer conditions (like monarchs do; check out this website to know where they are now!) or stick around and overwinter right here in protected spaces such as crevasses, underground nests, and within plant stems. If we have been enjoying supporting them throughout the season, it may be a good idea to continue to do so also throughout the winter. Let’s see some ways to do this.

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The good and the bad of carpenter bees: Can we get along?

Although we may love them with all our hearts, it is true that every one of our most beloved friends and family have sides that at times make us mad… and that’s no reason for us to love them less. I feel our relationship with pollinators and other beneficial insects is similar to that which we have with our loved ones: pollinators pollinate and play an important role in native plant reproduction and food production… and sometimes can become a nuisance if not properly managed. As for our loved ones, the fact that pollinators can become a nuisance shouldn’t stop us from supporting them; we just need to learn how to sustain our relationship while controlling its negative aspects. In today’s post we’ll talk about one pollinator in particular, with which our relationship can sometimes become complicated. Let’s talk about carpenter bees.

What are carpenter bees?

In our area, carpenter bees are large bees belonging to the bee genus Xylocopa. If you enjoy being outdoors, I am pretty sure you have already seen them. A very common species in our region is the eastern carpenter bee, which is about the size of a bumblebee, has a “dot” on its back and dark wings, and when exposed to the sun, has a shiny abdomen. These bees are very common in our area, and are very regular floral visitors of many ornamental and food-producing plants.

The eastern carpenter bee (left), a native to the mid-Atlantic, has a shiny abdomen, while bumblebees (right) have fuzzy and hairy abdomens. Photos: J. Gallagher, Wikimedia: R. Hodnett.

Because they are about the same size as bumblebees, carpenter bees are often confused with them. To differentiate them, a look at their abdomen will quickly allow us to know who’s who; carpenter bees have shiny abdomens, while bumblebees have very fuzzy and hairy abdomens.

The life cycle of a carpenter bees

It’s not random that carpenter bees are called that way. Their life cycle is tightly linked to wood, in which females dig holes to build their nests. Carpenter bees have impressive mandibles that they can use to chew soft wood to dig galleries in it. Although they may seem impressive, these are peaceful bees that sting only if physically and aggressively disturbed. In the spring, males of these bees establish and defend their territories, a strategy that will win them a female to mate with. During this defense, they “chase away” other males but also people who may be close to what they consider their spaces. These males are harmless, however, since they have no stingers and thus can’t sting.

the life cycle of carpenter bees from spring to fall
Life cycle of a carpenter bee. Photo: NC State Extension.

The life cycle of these bees goes hand-in-hand with the season. In the early spring the hibernating adults emerge, mate, and the females build their nests in the wood. These nests consist of galleries, at the end of which the females lay eggs and store food (nectar and pollen) for the developing larva. The larvae develop throughout the spring and summer, and by the end of the summer emerge as adults. These adults are the carpenter bees we usually see flying in the early fall. Once the weather starts becoming chillier, at the beginning of the winter, these adults return to some of the cavities and overwinter there, emerging the following spring, to restart the cycle.

Why can carpenter bees become a nuisance?

As we saw above, carpenter bees nest in wood. If a house or any structure is built of wood, they may pick it to build their nests. When this happens, these bees have the potential to affect the integrity of our wooden buildings. So, we see that while these bees are very important pollinators native to our region, this particular aspect is the one that can be problematic in our relationship with them. The good news is that there are solutions for this!

a carpenter bee seeks a nest side in wood
Carpenter bees nest in wood, which sometimes can be a part of human buildings. Knowing how to proactively protect wooden structures is the best way to manage this helpful native pollinator, while protecting our buildings. Photo: H. Jacoba.

If there are no nests yet in the wood

The best solution is of course not the reactive, but the proactive one. If we have important wood structures that we don’t want to see occupied by these bees, the best we can do is first to use hardwood (which these bees tend to dislike) and/or to treat the wood. The treatment consists in painting or varnishing the wood, which will deter the adults from nesting in it. A very good treatment is coating the wood with almond oil in the spring, which will deter the bees from choosing that section to nest.

Another proactive action that can be taken along with wood staining is to distract the bees from the wood that we want to protect. To do this, one can use pieces of wood that one may not be interested in keeping, and displaying them in other parts of the open spaces so that females choose to nest in those surfaces instead of in the wood we want to protect. Besides protecting the wood, this also allows us to support these important native pollinators from our region, all while reducing the potential negative impacts on our buildings.

If bees are already established in the wood

If carpenter bees are already established, there are several options. First, if the number of nests is really low, and if the structure can be removed and replaced, then this should be done and the new wood structure should be stained to protect it. If possible, the piece of wood that is removed can then be placed elsewhere in the green spaces around the property, which will provide nesting resources for this pollinator, and will simultaneously protect the house and support native pollinators.

carpenter bees flying around holes in old wood
Carpenter bees can sometimes establish many nests in structural materials. If this affects the integrity of the building, more extreme actions may be needed. Photo: JoeyZ51.

If the piece of wood can’t be removed and, in particular, if the nests appear to jeopardize the integrity of the building, a more radical action should be taken. In that case, the use of insecticides can be considered. If this path is taken, it is important to not perform insecticide applications without proper knowledge, meaning that this should be done by an expert applicator. This point is really important, because non-targeted and improper insecticide treatments can lead to a lower efficiency of the treatment on the carpenter bees, and the death of other non-target beneficial insects (e.g., other bees, beneficial pest control insects, etc.) that may become in contact with the treated region.

By Anahí Espíndola, Assistant 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!

Goldenrods & asters: Important fall flowers for pollinators

With the fall very clearly upon us, we tend to think more about falling leaves than flowers. Indeed, the big flower boom is ending, with all early-season flowers well past flowering. However, fall is a very important season for many pollinators, which still require food and shelter in preparation for the winter. In this blog, I would like to take a little bit of time to go over the importance of fall resources for pollinators, and what you can do to make sure they are available in your green spaces.

Why is fall special in nature?

The end of summer/fall is a special time for many organisms in our temperate regions. This is usually the last chance these organisms have to gather energy and resources to get ready for the winter. In the case of pollinators that are active during this period, the fall is key for collecting sufficient pollen (=food) for their nests, and for finding appropriate overwintering spaces for the adults and/or the offspring (take a look at this post to learn more about this), all of which will impact survival until the following year/season. If we want to help these pollinators, making sure that these resources are available is the best we can do!

Providing food for pollinators in the fall

Several native plants in our area flower in the fall and act as wonderful resources of pollen and nectar (and more!) for our late-summer/fall pollinators. These plants are easy to grow and once established provide abundant (nutritional) resources for our local insects.

Goldenrods

This group (Solidago spp.) consists of many species which flower in the late summer/fall. These plants are perennials that will create patches once established in an area. For this reason, they are easy to grow, although for this very same reason may usually require a bit of containment, since otherwise, they will easily spread everywhere. If the latter is a problem, plants can be grown in pots, where the containment issue is more easily resolved.

These plants support a large community of many different types of bees (many of which are specialists that can use only specific types of pollen and can be rare), as well as butterflies, flies, and wasps. In fact, more than any other herbaceous plant studied by Fowler/Droege, goldenrod (species in the genus Solidago) supported the most specialist bees (39 species). Importantly, because these plants create tall hollow stems, they can also act as nesting resources for stem-nesting bees. This way, these plants are great fall resources for many of our pollinators.

flowering goldenrod mixed with other asteraceae flowers
Goldenrods develop numerous flowers that provide support to a very large number and diversity of pollinators. In this picture, goldenrods stand out of a background of other yellow Asteraceae in a home garden. Photo: A. Espíndola

Two easy-to-grow species that one can find in several native nurseries are the tall goldenrod (Solidago altissima) and Canada goldenrod (Solidago canadensis). Both species have long stems that end with many yellow inflorescences. Both of them flower in the late summer and fall and can be easily grown in green spaces, especially drier sites that are exposed to the sun. As said before, although these plants are great pollinator magnets and resources, they tend to spread readily, so, unless that is wanted, they require some control once they start spreading in an area.

Asters

Asters are another group of plants native to our region that acts as a great pollinator resource in the fall. These plants are also perennials and can be small or become shrub-like, depending on the species. Unlike the goldenrods we were talking about just above, these plants tend to display a larger variety of floral coloration, with flowers going from white, to pink, and purple, depending on the species. Like goldenrods, these plants provide both food and nesting sites to many pollinators. Their flowers attract a very large variety of pollinators (bees, butterflies, flies, beetles, wasps) during a time when there is little else to feed on. The flowers of these plants are also known to support specialist and often rare bees, which depend strongly on its pollen for survival, as well as many butterflies, including Monarchs. Their stems are also great sites for stem-nesting bees. Finally, their leaves support the larvae of many local butterflies.

purple flowers of new england aster and a monarch butterfly
New England asters can be obtained from native plant nurseries and are able to support a very large diversity of pollinators, including rare and specialist bees, as well as adults and larvae of many butterflies. In this picture, we can see a Monarch adult feeding on the characteristic purple/blue flowers. Photo: Glenn Marsh

A lovely species that can be grown in our green spaces and provides hundreds of blue/purple flowers is the New England aster (Symphyotrichum novae-angliae). This perennial herbaceous plant can be obtained from nurseries and will grow three to six feet tall in the summer (but it can be cut back in mid-summer if you want to keep it shorter). The plant requires at least some sun and does well in a variety of soils we find in Maryland. I love watching the lovely cute flowers, and all the activity they attract. This is really one of my personal fall garden highlights!

By Anahí Espíndola, Assistant 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!

Let’s find skipper butterflies in Maryland using iNaturalist!

A Silver-spotted Skippper on wild bergamont flowers in Maryland, observed recently by iNaturalist user Andy Wilson

I have been writing blog posts for Maryland Grows on a regular basis for a while. To do this, I usually meet with Christa, the blog manager, every 6 months and plan on the topics I will cover over the next few months. When we do this, we seek to cover the needs we see from readers, but sometimes the topics come to us as a result of our discussions. This is exactly what happened for today’s topic. Today, let me tell you the story of how this came to be, and at the same time show you a great free tool available at our (literal) fingertips!

The story

Picture myself and Christa on Zoom, planning dates and topics for the next few months. It is February and it is cold outside. We have been making our way through the upcoming months, thinking of what each one will look and feel like, and what will be growing and buzzing around in each of them. August comes. How is August in Maryland? What do we usually see around? What issues are common in green spaces in August?

I think of August and in my very pollination-biologist-biased way start thinking of the pollinators we see in August… And what comes to me is “butterflies!” I remember writing about butterflies in the past, so maybe butterflies are a bit redundant as a blog topic. However, I don’t remember writing about a specific group of butterflies called “skippers,” which are common in Maryland. So, sure, let’s write about skippers, but what skippers are around in August? As we discuss and try to narrow down the topic, I open this incredible tool I use very regularly to learn about local species, report observations I make, and do research in my lab. This magical incredible tool is called iNaturalist.

So, there I am, opening iNaturalist’s website, and doing a quick search to find out the most common and most abundant skippers we find in Maryland in August. I am doing this, and Christa is intrigued; what am I doing? How am I figuring this out? I decide to share my screen to show her what I’m doing. Christa is amazed. You can do all that with iNaturalist?! The world needs to know! So, there we have it. Our blog topic showed itself to us. Today’s blog will be about what iNaturalist is, how to use it, and what type of information we can share with and learn from it. I hope that this blog will motivate you to start using it as well, and, like me, every time learn something new about species here and elsewhere in the world.

iNaturalist; ever heard of it?

We live in the times of social networks, like Twitter, Instagram, and Facebook… And as it turns out, social networks are really useful to science too! iNaturalist is one of those networks!

iNaturalist is a global social network that allows people to submit, find, and explore biodiversity observations from around the world. What does this mean? This means that through this network, every time a person observes an organism anywhere in the world, they can take a picture of it, upload it to iNaturalist, and then have the network help them identify what it is through its picture (using image recognition software), its location, its date, and the input of other members. This information is then stored in a public database, which can then be explored easily by anybody, including scientists, you, me, kids, conservation agencies, and more! At the end of the day and using all these data, the network can output maps and other information of any species ever added, allowing for the reported localities to be found, and, if the user wants to, visited to try to see the organism in question. Today, iNaturalist has over 5 million users worldwide, with over 109 billion observations of over 380,000 species!

OK. But how does iNaturalist work?

To explain this, let’s come back to my skippers story. I am talking to Christa and want to know what the most abundant skipper in Maryland may be, and whether it is present in August. To do this, I first go to the iNaturalist website (if on a computer; otherwise, I would open the app on my phone). This is what the page looks like.

Screen shot of the iNaturalist home page
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The more the merrier: community actions for pollinators

bumble bee on a purple coneflower

Besides it being the month when summer starts, June is a great month because it is when Pollinator Week happens! 😊

Tagging along with that week, in today’s post I want to talk about some actions you can take with(in) your community to help pollinators! Because, if we want to help pollinators, a very valid and effective way to amplify your actions is to get others on board! Here, a non-extensive list of ideas.

1. Become a Bee City

Ask your City or Campus to become a certified Bee City or Bee Campus USA. Bee Cities and Campuses are certifications that cities and campuses across the USA can obtain if they implement a series of actions (“commitments”) established by the Xerces Society. Once these actions are done, the City or Campus in question becomes certified as a pollinator-friendly space. The types of actions outlined are really activities that lead to increasing education on pollinators and pollination, to improving pollinator habitat on the institution’s land, to promoting actions in the way that the institution functions that may allow for increasing pollinator support (see here for city commitments and here for campus commitments). Becoming a Bee City or Campus is not hard, and most institutions say yes if their members ask. If you think this is something you would like your City and/or Campus to do, reach out to your representatives or leadership and get them on board! And to have an idea of what cities and campuses are already involved, take a look at the Bee City USA affiliates.

2. Organize a Pollinator Week Event

Pollinator Week is a National event organized by the Pollinator Partnership and includes many possible actions that lead to increasing pollinator survival and/or awareness. This year, Pollinator Week will be happening June 20-26. One can participate in activities already organized by others, or one can propose and host an activity! If you would like to get together with your community and organize an event, do it, and then submit it to the Pollinator Week event list! That way, others will know about it and will participate as well! To submit (or participate in) an event, go to the bottom of the Pollinator Partnership page.

Here are some activities happening in Maryland: bee hotel building workshop in College Park, MD, webinar in Greenbelt, MD, pollinator catch-and-release in Saint Leonard, MD, and several activities in Howard Co., MD.

Pollinator Week, June 20-26, 2022 logo

3. Ask your city to host a No-Mow Month in early-spring

Early-spring pollinators emerge usually when very few plants are flowering, meaning that the early spring is a critical time for these pollinators. In human-occupied landscapes like cities or suburban areas, a lot of the landscape is occupied by lawns, which can provide some flowers early in the spring. No-Mow Month (usually April or May, depending on the city’s conditions) is an action that seeks to allow the availability of the early flowers in lawns so that local pollinators can survive during the early spring. Once other plants in the landscape start flowering (usually at the end of April in most of Maryland), the lawn can be mowed with this not negatively affecting pollinators.

It is important to note that this action is based on voluntary participation, meaning that participants opt-in (instead of being mandated to do it). This action has been shown to be effective in increasing pollinator diversity and abundance in regions where it is implemented, and is not associated with excessive lawn growth because it occurs so early in the season. Further, it can be strengthened with native plantings, which can boost its effects and also support local landscapers during the reduced-mow month. Localities where the action has been implemented tend to have high adoption rates, increased nature awareness, and willingness to further support biodiversity around homesteads, with no- to very-reduced vermin occurrence.

This action usually requires some temporal amendments to City Code (e.g., to ensure that participants will not be penalized if their lawns surpass the maximum allowed height during the no-mow month) so it needs approval by City Councils. Although this may sound really complicated, it is not, and several Cities in Maryland have implemented this program very successfully during the month of April (see here for College Park, MD, and here for Greenbelt, MD), following Appleton, WI’s trailblazing action. If you think this is something you would like to implement in your community, get in touch with these cities’ Bee City USA committees so they can share their expertise, and then contact your representatives to ask them to adopt this action where you live!

No Mow April Collage Park sign

4. Ask your community to establish pollinator-friendly plants and nesting resources

Communities can also support pollinators through the way they decide to landscape their land. Requesting your community leadership to implement pollinator-friendly gardens and offer nesting resources for pollinators (e.g., bee hotels, create small wild spaces) is a really good way to help pollinators at a larger scale. To do this, you can get in touch with you City/Town Horticulturist and/or Public Works people, and request this. If you would like to implement this in your neighborhood and on private land, you can coordinate with your neighbors and create plots of native plants or small nesting areas in everybody’s green spaces. A very effective way to do this in Maryland is by establishing a neighborhood Green Team. If you would like to know about how to do this, take a look at this page of recommended native plants and this list of native plants that do well in our area.

Chart listing easy-to-grow native plants that support pollinators

5. Ask you city/town/neighborhood to adopt an IPM plan

Although we tend to think about helping pollinators only by planting flowers and maybe creating nesting spaces, pollinators also can be helped by the way we manage our landscapes. For example, herbicides and pesticides can be sometimes very harmful to pollinators, or cutting plants at certain times of the year can really negatively affect them. Reducing the use of pesticides and herbicides, or changing the way we manage our own private land is one possibility. However, cities, towns, neighborhoods, schools, and campuses also manage their public lands! For that reason, they can also implement actions to manage spaces in ways that support pollinators.

chart explaining Integrated Pest Management in 5 steps

A very good way to institutionalize this is by requesting these institution to implement Integrated Pest Management (IPM) plans. IPM is a way of controlling pests and increasing “beneficial” organisms in a given space by means that reduce the use of pesticides and herbicides. These plans establish a framework that allows institutions to still control pests and diseases, while reducing the negative impacts on biodiversity that some conventional practices have. These plans can be very general or very specific, and if your institution does not have one, it may be time to ask them to implement one! To do this, get in touch with your institutional horticulturist or your government representative. Here are some examples: city, campus and school district plans.

By Anahí Espíndola, Assistant 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!

Bees to look out for: leaf-cutter bees!

Spring is well-established and many flowers have already started to bloom. In my garden, I have seen several sizes and shapes of insects visiting flowers, going from small flower flies to butterflies, to very tiny and shiny, fuzzy large, and very large bees. And with all these flying organisms starting to come around us, I thought today would be a really good time to introduce you to some really cool bees that are very common in our area: the leaf-cutter bees!

What are leaf-cutter bees?

As its name suggests, these are solitary bees known to cut leaves (now you may be thinking, “duh, I could have guessed that without a blog post”, but bear with me!). These bees belong to a very large family of bees called Megachilidae, which is present on all continents except Antarctica and well-represented in our region.

Like most solitary bees, the female of leaf-cutter bees builds nests with small brood cells, in each of which a food provision is left and one egg laid. And this is where the “leaf-cutter” name comes from. When building their nests, many of these females line their brood cells with specific materials, in particular plant tissues. In fact, many of the species are known to cut leaves and/or petals to line their nests, using them to stabilize the brood cells, and likely to provide protection to the larva and the food provisions. In a fascinating way, it is suspected that these bees are able to exploit the antimicrobial effects of certain compounds present in these flowers and leaves, indirectly using them to protect their offspring until they finish their development in the nests.

If you ever saw neat and relatively large holes that seem to suddenly pop up on certain plants in your green spaces, it is very likely that they were made by some of these bees that may be nesting close to you! If you keep an eye out on those plants, it is very likely that you will end up seeing these busy bees carefully cutting, then rolling, and finally flying away with the neat plant circles!

Female leaf-cutter bee cutting a leaf
Leafcutter bee nest and brood cells made with leaf pieces
Megachilids are known for cutting leaves that they use to line the brood cells of their nest. Note that here the nest is in a soil mound and each brood cell is completely covered with leaves but capped and separate from the neighboring cells. In this nest, each cell contains one egg. Photo: E. Soh.
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What are local ecotype plants and why do they matter to pollinators?

With the planting season upon us, many of us are starting to think about what flowers may be the best for our gardens and pollinators. We may have started to look into floral mixes or even flower starts, but probably there are too many choices and now we’re overwhelmed and don’t know what to do. In previous posts, we talked about the importance of diverse floral choices and how appropriate native species are when choosing plants for pollinators. There is, however, an extra twist that is becoming more mainstream in this story and today I want to talk about it. Let’s chat about local ecotypes, what they are, what they contribute, and how to get them (and how to not get them).

What are local ecotypes?

In a few words, local ecotypes are native plant species that have a genetic background typical for the local region and adapted to it. I know, there were a lot of technical words in that sentence, so let me break it down to make it easier to understand.

Like all organisms, plants have lineages that reflect their ancestry. In the same way that we as humans are genetically more closely related to members of our own family than to those of other families, plant populations are also more closely related to other plants of the same species that live close to them. From a genetic point of view, this means that plants that come from regions close to each other will tend to have more similar genetic characteristics than those from regions far apart from each other. This genetic makeup specific to a given region is what we call broadly a local genotype.

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