We study gardens: the plants, insects, animals, people, decisions and management practices that either improve or degrade a garden’s ability to promote environmental and human health.

An underlying premise of our work is that gardens are important and understudied systems, that are key to building more sustainable, healthy and just communities.  

Garden Ecology Lab, Fall 2017: (left to right) Signe Danler, Gail Langellotto, Lucas Costner, Isabella Messer, Michael Nelson, Aaron Anderson

Our garden pollinator work is supported by a generous donation from Spike Wadsworth and Y. Sherry Sheng.

garden ecology lab

garden ecology lab

Urban agriculture has received a lot of attention over the past decade, as more folks are looking to localize their food supply, reduce food miles, and/or exert greater control over their food. Urban agriculture, however, brings a distinct set of challenges from farm systems in more rural regions. For example, urban farms tend to be relatively small and diverse (which can make it challenging to rotate crops), and are often close to neighborhoods and housing developments (which may make urban farms more prone to nuisance complaints). Urban farmers tend to be younger and to have less experience in agriculture, compared to rural farmers, and in need to high levels of technical assistance from Extension and other providers (Oberholtzer et al. 2014). However, many of the resources that Extension has to offer are focused on traditional growers, rather than new urban farmers.

Our lab group wanted to examine an issue that is specific to urban growers, and for which we could find very little information: urban agricultural soils. Soil scientists have prioritized research on urban agricultural soils as a key priority for the 21st century (Adewopo et al. 2014). Yet for his thesis work, Mykl Nelson could only find 17 academic papers that looked at urban agricultural soils in the United States. Most of these studies focused on

residential-scale or community-scale urban agriculture (in home or community gardens). Only one paper looked at soils on an urban farm.

Still, residential- and community-scale gardening is an important type of urban agriculture. In Portland, a conservative count of 3,000 home gardens collectively covers more than 20 acres of land (McClintock et al. 2013). In Chicago, residential food gardens cover 29 acres of land, and represent 89% of all urban agriculture (Taylor and Lovell 2012). In Madison, WI, more than 45,000 food gardens cover more than 121 acres of land (Smith et al. 2013).

For Mykl’s thesis, he looked at urban soils from 27 Master Gardener-tended gardens, in Portland and Corvallis, OR. Even though all gardens were tended by OSU Extension trained Master Gardeners, they were incredibly diverse: 74 different annual crops, and 58 different perennial crops were grown across these gardens. Unique crops included kalettes, papalo, thistle, savory, paw paw, quince, sea berry, and service berry, among others.

In terms of the soils, Mykl found that soils were within the recommended range for physical parameters, such as bulk density, wet aggregate stability, and soil compaction. However, home garden soils tended to be over-enriched in soil organic matter. Growers generally aim to foster soils that are between 3-6% organic matter. However, Mykl’s tested soils were on average 13% organic matter! Raised beds were on average 15% organic matter. In ground beds were a bit better: 10% organic matter, on average. So to put this another way, Master Gardener vegetable garden soils had 2-5X the recommended level of organic matter for productive agricultural soils. We suspect that Master Gardeners were annually adding organic matter to their soils, without necessarily knowing the baseline levels in their soils. Adding more organic matter, without knowing where you’re starting from, encourages over-applications.

Does that matter? Afterall, for years, we have been preaching that if you have sub-par soils, ‘just add organic matter’. Biological activity in these soils was great! But, the excess in organic matter promoted excess in several soil nutrients. Garden soils were over-enriched in phosphorus (mean phosphorus across all gardens was 2-3X recommended levels. Potassium in some gardens was 5X recommended levels! Gardens were over-enriched in magnesium and manganese, too. Nutrient excess was worse in raised beds, compared to in-ground gardens.

Unexpectedly, Mylk found the highest lead levels in raised beds. Often, we tell gardeners to grow their food in raised beds, to avoid heavy metal contaminants. Why would there be high lead in raised beds, if we weren’t finding elevated lead levels in nearby in-ground beds? We suspect that the lead might be coming in from compost waste that can be purchased on the retail market. If a compost product makes no nutritional claim, then it is exempt from analysis and contamination limits.

We can’t wait to finalize this work for publication. In the meantime, I wanted to share a brief update on this work.

Mykl will be defending his thesis on May 31st. We’re trying to arrange an online broadcast of the public portion of his thesis defense (1pm-2pm, May 31st). I will update this post, if we are able to get an online link for his presentation.

The Mining Bee

This entry is from Isabella Messer, an undergraduate horticulture student at Oregon State University. It highlights a common Oregon pollinator.

Halictus ligatus covered in pollen from the Morris Arboretum.

Halictus ligatus(Say, 1837), otherwise known as the Mining Bee and which can be classified as a Sweat Bee, are charming little(7-10mm) pollinators who are essential to our success as gardeners and farmers. These little generalists can be found worldwide in temperate climates with over 330 species recorded, so it would be no surprise if also you see them in your garden(1).

Halictus as a genus is very diverse in appearance with colors ranging from metallic greens, blues and sometimes even purple(2). Mining bees on the other hand, can be identified by their small dark brown or black bodies with well-defined yellow or black bands around their abdomens(3). Many of the females but no males will have scopa, which are long dense hairs on their hind tibia for carrying pollen(2). While they may not be the most flamboyant in their genera, their bodies are metallic and sparkle in the sun, giving them an understated but undeniable charm.

H. ligatus on an unidentified flower.

As their name suggests, Mining Bees build their nests underground and the Halictus gendera can demonstrate a very diverse gradation of social organizations within their nests(4). These organizations can range from solitary, communal, semi-social or eusocial(4).

If you are looking to attract some of these lovely and helpful pollinators to your gardens, be sure to leave a sunny and loose patch of soil close to some of your flowers available. Seeing as Mining Bees are broad generalists, there is no need to plant specific flowers or herbs to attract them. They will be beneficial for all of your flowering plants.

 

Sources

  1. Buckley, K., Nalen, C. Z., & Ellis, J. (2011, August). Featured Creatures: Sweat or Halictid Bees. Retrieved April 30, 2018, from http://entnemdept.ufl.edu/creatures/misc/bees/halictid_bees.htm
  2. Elliot, L. (2005, April 8). Species Halictus ligatus – Ligated Furrow Bee, Halictus (Odontalictus) ligatus. Retrieved April 30, 2018, from https://bugguide.net/node/view/14566
  3. Potts, S., & Willmer, P. (1997). Abiotic and biotic factors influencing nest-site selection by Halictus rubicundus, a ground-nesting halictine bee. Ecological Entomology,22(3), 319-328. doi:10.1046/j.1365-2311.1997.00071.x
  4. Rehan, S. M., Rotella, A., Onuferko, T. M., & Richards, M. H. (2013). Colony disturbance and solitary nest initiation by workers in the obligately eusocial sweat bee, Halictus ligatus. Insectes Sociaux,60(3), 389-392. doi:10.1007/s00040-013-0304-8

This entry is from Isabella Messer, and undergraduate horticulture student at Oregon State University. It highlights a common Oregon pollinator.

Photo by Marc Kummel

As winter starts to wind down, daffodils and crocuses begin to emerge, and butterfly enthusiasts start looking forward to another season of spotting some of my favorite pollinators, the Lepidoptera. While peak butterfly season still may be a ways off(5), there is no reason to delay in learning about and exploring the world of butterflies, as I have been doing these last few days with Ochlodes sylvanoides(Boisduval, 1852), or the Woodland Skipper.

These little beauties can be identified by their tawny upperwings which sport a black border and large red patches on their underside(1,2). The hindwings of the Woodland Skipper can vary greatly from being unmarked to being yellow or even showing a chevron pattern(1, 2).

Woodland Skippers are native to Oregon and in fact, are native to most of the western United States. With a range that stretches from South Dakota to Oregon and from Vancouver, BC to San Diego, CA, Skippers are one of the most abundant butterfly genera in the US(6,2). The preferred habitats of Woodland Skippers include grassy areas in chaparral, mountain meadows, and hillsides(1). For those of you living among

Photo by Claire Christensen

With Portland’s many hills, it seems likely that your garden would be an appealing place for these butterflies to make their home. If you are looking to attract some Woodland Skippers to your garden, this may not be terribly hard as O. sylvanoides are generalists. Larval food plants consist largely of common grasses such as bermuda, wildrye, wheatgrass, and canary(1,2). Adult food plants can vary widely, from Oregon natives such as yarrow, sweet pea, and willowherb to others such as catmint, tansy, and zinnia(1). If you are having a slow start to your gardening season and have lots of patches of exposed dirt, that is okay seeing as adult Woodland Skippers will also sip salts from mud puddles(1).

Keep the hope of summer and Woodland Skippers in your garden alive, as this winter season begins to come to an excruciating close, and when August(3,4) finally rolls around, keep your eyes open for these tawny beauties.    

References

  1. Lotts, Kelly and Thomas Naberhaus, et al. “Woodland Skipper”. Butterflies and Moths of North America. 2017. Butterflies and Moths of North America. http://www.butterfliesandmoths.org/
  2. Woodland Skipper — Ochlodes sylvanoides.  Montana Field Guide.  Montana Natural Heritage Program.  Retrieved on February 22, 2018, from http://FieldGuide.mt.gov/speciesDetail.aspx?elcode=IILEP72010
  3. Allen, Nancy., et al. “Create a Butterfly Garden”. 2002.  http://ir.library.oregonstate.edu/concern/administrative_report_or_publications/kd17ct04f
  4. Chu, Janet R.. “Butterflies A Continuing Study of Species and Populations In Boulder County Open Space Properties – 2011 Inventory and 2007-2011 Analyses”. Boulder County Parks and Open Space and Boulder County Nature Association. Dec. 2011. https://assets.bouldercounty.org/wp-content/uploads/2017/03/research-report-2011Chu.pdf.
  5. Kaufman, Kenn. “Year-round Guide to Butterflies”. Birds and Blooms. 2016.http://www.birdsandblooms.com/gardening/attracting-butterflies/year-round-guide-butterflies/
  6. Department of Systematic Biology, Entomology Section, National Museum of Natural History, in cooperation with Public Inquiry Services Information Sheet Number 189. “Butterflies in the United States”. Smithsonian. https://www.si.edu/spotlight/buginfo/butterflyus

It’s been a busy month in the Garden Ecology Lab.

  • Gail’s manuscript on bees in home and community gardens has been published in Acta Hort. Briefly, the results of this literature review are that: 213 species of bee have been collected from a garden habitat; gardens have fewer spring-flying and fewer ground-nesting bees, compared to non-garden sites; I suspect that over-mulching might be cutting out habitat for ground-nesting bees in gardens.
  • Aaron presented his first Extension talk to the Marion County Master Gardeners. This 90-minute talk was an overview of using native plants in home gardens.
  • The entire lab is getting ready to present their research results at the 2018 Urban Ecology Research Consortium annual conference, to be held in Portland on February 5th. A few highlights of our presentations, can be found below.

Gail’s Poster on Urban Bees: we sampled bees from 24 gardens in the Portland Metro area (co-authored with Isabella and Lucas)

  • Langellotto and Messer UERC 2018 Poster: click to see preliminary results
  • Most of the bees that we collected await identification. We did find a moderate relationship between lot size and bee abundance: larger yards hosted more bees. But, we also found evidence that suggests that intentional design can influence bee abundance: one of our smallest gardens (site 56 = 0.1 acre), located in the Portland urban core (surrounded by lots of urban development) had the second largest number of bees (42), of the 24 gardens sampled. This garden was focused, first and foremost, on gardening for pollinators. The plant list for this garden (photos, below) includes: borage, big-leaf maple, anise hyssop, globe thistle, California poppy, nodding onion, yarrow, fescue, goldenrod, Phacelia, Douglas aster, lupine, mallow, columbine, meadow foam, yellow-eyed grass, blue-eyed grass, coreopsis, snowberry, Oregon grape, trillium, mock orange, pearly-everlasting, serviceberry, coneflower, blue elderberry, currant, milkweed, dogwood, shore pine, crabapple, cinquefoil.

 

 

 

 

 

 

 

 

Mykl’s Poster on Urban Soils: we sampled soils from 33 vegetable beds across Corvallis and in Portland (co-authored with Gail)

  • All gardens were tended by OSU Extension Master Gardeners.
  • Gardens were over-enriched in several soil nutrients. For example, the recommended range for Phosphorus (ppm in soil) is 20-100 ppm. Garden soils averaged 227 ppm. The recommended range for Calcium is 1,000-2,000 ppm, but the mean value for sampled beds was 4,344 ppm.
  • Recommended ranges gleaned from OSU Extension Publication EC1478.
  • There was a tendency for soils in raised beds to be over-enriched, compared to vegetables grown on in-ground beds.
  • Data suggests that gardeners are annually adding additional soil amendments or compost, and that there has a build up of certain elements in the soil.

Aaron’s Talk on Native Plants: measured bee visitation to 23 species of native and 4 species of non-native garden plants (co-authored with Lucas)

  • Field plots established at the North Willamette Research and Extension Center
  • In the first year of establishment, of the 27 flowering plants that were the focus of this study, seven natives (lotus, milkweed, camas, strawberry, iris, sedum, blue-eyed grass) one non-native (Lavender) did not bloom, or else did not establish
  • Several natives attracted more bees than even the most attractive non-native (Nepeta cataria, or catmint). These include:
    • Gilia capitata: Globe Gilia
    • Madia elegans: Common Madia
    • Aster subspicatus: Douglas’ Aster
    • Solidago candensis: Goldenrod

All bees have been pinned, labelled, and data-based. Now we’re (and when I say ‘we’re’, I’m mostly referring to Lucas and Isabella) are going through the painstaking process of photographing all specimens: head on, from the top, and from each side. We’ll then start sorting them by morphotype (how they look), and working to identify them. Some of the bees are very common, and fairly easy to identify (like Anthidum manicatum, Bombus vosnesenskii, Apis meliifera). Others will take a bit more time and expertise to get to species.

You can take a look at the entire album, representing about 150 of the nearly 700 collected bees. We’ll be adding the rest of the bees, as we can.

We collect and pin the bees, because most are difficult to identify, without getting them under a microscope, and without the help of a museum-level bee specialist. For those bees that are easy to identify by site (such as the ones listed above), we only collect one per garden (so that we have a record of its presence). We don’t collect multiple specimens of the same species, if we can identify it in the field. And, we don’t collect obvious queens (larger, reproductive bees).

We collect using a combination of water pan traps and hand collection. For hand collection, we use a pooter (an insect aspirator) for the smaller bees and baby food jars for the larger bees.

Water pan traps. We buy plastic bowls from the dollar store, prime them, and paint them with UV paint that is optimized for the wavelengths that bees see.
Here, I’m holding an insect aspirator, otherwise known as a pooter. You can suck insects off of flower heads without damaging blossoms, by carefully placing the metal part of the pooter, over the bee. It is then sucked into a small plastic vial, which I’m holding in my right hand.

This is such an exciting part of the research for me. I find myself obsessing over the photos, trying to organize them in my mind, and to at least get them to genus. Grouping them by genus makes it easier for an expert to sort through and identify them. And, I’m so grateful for their assistance, that I want to make it as easy as possible for them!

We’ve collected bees from gardens near Forest Park, in Portland’s city center, and in outlying suburbs. We’ll analyze the data to see if there are any patterns associated with garden location (forest, city, suburbs), or to see if there are specific bees that are only found in forest gardens, for example.

 

This entry is from Isabella Messer, an undergraduate horticulture student at Oregon State University. It highlights a common Oregon pollinator.

 

Despite the misleading name, we have unfortunately not discovered a new cross species between California butterflies and tortoiseshell cats. Even though this butterfly has a larval stage instead of a kitten stage, the California Tortoiseshell Butterfly is still a beautiful representative of the Lepidoptera. 

A California Tortoiseshell flashes its bright upperwing. Photo by Doug Backlund

As you may be able to guess, the largest populations of the California Tortoiseshell (Nymphalis californica (Boisduval, 1852)) are located across California(1). While the majority may be in California, the California Tortoiseshell habitat range stretches south from British Columbia to Mexico and east from California to Wyoming(1). When the California Tortoiseshells experience a population explosion in the summer(1), some populations have been known to travel as far east as Vermont, New York and Pennsylvania(2). 

These lovely butterflies can be identified by their bright orange upperwing which features black spots and black border(1). Their underwings are mottled brown and gray and resemble dead leaves(2). When in larval(caterpillar) form, N. californica can be identified by its all-black appearance with the exception of a white line running down its back and the slight blue at the base of its black spines(2).

The cleverly disguised underwings of the California Tortoiseshell. Photo by Doug Blackbund

Unlike some of the other pollinators that we have discussed over the months, the California Tortoiseshell Butterfly is somewhat picky when it comes to choice of host plant for the immature and habitat mature butterflies. Adults will oviposit (lay eggs) only on various species of wild lilac (Ceanothus) where the immature butterflies will be hosted until they reach maturity(3). Adult N. californica are less specific about their habitats by the time the reach maturity. They can generally be found in mountainous regions in chaparral, woodland and brush areas(1). 

While these charming butterflies may not be extremely common in the Portland area due to its low elevation, if you take a trip up to Mount Hood this coming summer, it is more than likely you will run into one of these beauties.

Sources:

  1. Lotts, Kelly and Thomas Naberhaus, et al. “California Tortoiseshell”. Butterflies and Moths of North America. 2017. Butterflies and Moths of North America. http://www.butterfliesandmoths.org/
  2. Ross A. Layberry, Peter W. Hall, and J. Donald Lafontaine. “California Tortoiseshell”. Canadian Biodiversity Information Facility. 9 Jul. 2014. http://www.cbif.gc.ca/eng/species-bank/butterflies-of-canada/california-tortoiseshell/?id=1370403265564
  3. Art Shapiro. “Nymphalis californica”. Art Shapiro’s Butterfly Site. http://butterfly.ucdavis.edu/butterfly/Nymphalis/californica

This entry is from Lucas Costner, an undergraduate horticulture major at Oregon State University.  It highlights one of the plants that Aaron Anderson is using in his research.

A native been rolls around inside of a California poppy at the North Willamette Research and Extension Center.

Having moved to Oregon from Michigan this past spring, one of my first memories of the state was the explosion of bright orange and yellow flowers lining the interstate and covering the hills. These ubiquitous flowers were, of course, California poppies (Escscholzia californica). Native to a range covering southern Washington south to the Sonoran Desert, the plant has spread throughout most of North America and onto other continents thanks to human intervention (1). This should come to no surprise to those familiar with the plant, because it is easy to grow and thrives in average soil, as long as drainage is good and there is plenty of sun (3).

California poppies can be grown as perennials or annuals, depending on the severity of the winters (3). The grey-green, finely divided foliage erupts with brightly colored flowers in the spring, but can continue flowering across the growing season if conditions are favorable (1). Long, spindly seed pods appear quickly following pollination and, once dry, easily explode, spreading baby poppies up to six feet away from the parent plant (1). If you’re looking to add these beauties to your own garden, it is best to spread seeds on the surface of the soil in the fall to ensure that dormancy is broken (1). But gardener beware: once established, California poppies are around for the long haul (3).

These flowers have been grown or collected for hundreds of years by the societies that have encountered them (1). Indigenous North Americans first used the plants for a variety of medicinal purposes and the plant quickly rose to fame in Victorian gardens after it was collected by David Douglas for the Royal Botanical Society of England in 1836 (1, 3). Western medicine has also found use of the California poppy, isolating over 30 chemicals for uses ranging from anti-bacterial agents to the treatment of cancer (1). For horticultural purposes, the Royal Horticultural Society today recommends planting along borders, for cut flowers, to create a sense of informality as in a cottage garden, as well as for gravel and rock gardens (4).

The act of gardening is unique in that it strikes a balance between control of and surrender to the natural world. On the one hand, the plants we decide to grow on our little slices of paradise are an irrevocable extension of us and our own stories; however, these plants have their own stories to tell and they transform us into participants of these stories whether we are willing or not. I’ve never heard anyone say, for example, that they planted such-and-such prize-winning hosta to attract deer to their garden. Yet, when these majestic 150-pound creatures sneak silently into our yards for a midnight snack, it’s hard to argue they weren’t invited. The plants we choose act as our ambassadors to a biotic world just beyond our grasp, providing food and habitat for a full spectrum of wildlife. On a larger scale, the landscapes we cultivate can collectively affect everything from water resources to the climate.

While it’s true that I’ve never heard anyone say they are planting for the deer, us gardeners have certainly taken a liking to another sort of creature. The insects of the Anthophila clade, otherwise known as the bees, have found a special place in our hearts. Maybe writer Michael Pollan was on to something when he recognized, in The Botany of Desire, the mirrored way in which the bees visiting his garden had found themselves in the servitude of the plants just as he was. While the gardener tends to the plants’ every need, the bee unwittingly ensures their reproductive success by transporting pollen from flower to flower. Or maybe its the recognition that we ultimately depend on pollinators for our own food security and survival. Whatever the underlying cause behind our species’ admiration of bees, cultivating a diversity of flowers is the surest way to invite them to and help them persist in our landscapes.

A syrphid fly pays a visit to a California poppy at the North Willamette Research and Extension Center.

Whether you sow the seeds of the California poppy simply for its beauty, for its natural history, to help prevent erosion, or for any other reason, you will also inevitably be providing a source of food for our favorite insects, the bees. Surprisingly California poppies don’t provide nectar for pollinators, just pollen, but they are still heavily visited by our native bumblebees, sweat bees, and mining bees, as well as the European honey bee (Apis mellifera) (1, 2). They are also visited by beautiful butterflies, beneficial minute pirate bugs, and glistening beetles (1). Additionally, from our observations at the North Willamette Research and Extension Center, I can personally attest to the California poppy’s popularity amongst a variety of syrphid flies.

As a student interested in creating functional habitat for both humans and wildlife, it truly matters little to me on its face if a plant is native or not. Gardens consisting of native plants can be just as gorgeous and moving as gardens consisting of exotic species — this is true. What does matter to me are the relationships these plants have with other organisms, and what that looks like in a world increasingly and unavoidably modified by humans. So, whether or not you decide to bring the California poppy or any other native plants into your own garden, I hope you do feel inspired to think about these plants in terms of their role in the wider community of life with which we share this planet.

Sources:

  1. Smith, C. 2010. Plant guide for California poppy (Eschscholzia californica). USDA-Natural Resources Conservation Service, Plant Materials Center. Lockeford, CA 95237.
  2. Garvey, Kathy Keatley. “Why Honey Bees Forage in California Poppies.” Bug Squad: Happenings in the Insect World, University of California, 18 Mar. 2014, ucanr.edu/blogs/blogcore/postdetail.cfm?postnum=13179.
  3. Nelson, Julie. “California poppy (Eschscholzia californica).” Plant of the Week, USDA Forest Service Rangeland Management & Vegetation Ecology – Botany Program, www.fs.fed.us/wildflowers/plant-of-the-week/eschscholzia_californica.shtml.
  4. “Eschscholzia californica.” Royal Horticultural Society, www.rhs.org.uk/Plants/106119/Eschscholzia-californica/Details.
A female virescent green metallic bee. Image from United States Geological Survey Bee Inventory and Monitoring Lab.

This entry is from Lucas Costner, an undergraduate horticulture student at Oregon State University. It highlights a common Oregon pollinator.

While there are approximately 4,000 species of native bees in the United States (an estimated 500 of which call Oregon home), I’ve decidedly landed on one as my very favorite (1, 2). This flying iridescent blue-green gem, covered in golden hairs, and sporting a pitch black abdomen with white or yellow bands is Agapostemon virescens, the virescent green metallic bee. Found throughout the United States and southern Canada, these members of the sweat bee family (Halictidae) are common and beautiful (3).

As with other species of the genus Agapostemon, the virescent green metallic bee is a communal soil nester (3). These nests are composed of underground tunnel systems, marked by a main vertical burrow that branches off into several larger nesting areas complete with horizontally running tunnels and cells (4). In these cells, female bees leave a gift of pollen and nectar for a single egg before filling the tunnel with an insulating layer of soil (4). Soon a babe is hatched and, after eating and growing, the mature offspring dig their way out to start foraging!

Virescent green metallic bees are polylectic, meaning they collect pollen from a wide variety of floral resources (4). This is lucky for us gardeners, because we can plant from over a dozen common flower genera and provide the bees with forage. This point is underscored by a 2014 study that sampled bee species in Chicago, finding that the virescent green metallic bee was one of the most common species in the city (5). The same study noted that in more densely populated neighborhoods, the overall composition of bees shifted to more heavily consist of  bees like the virescent green metallic bee and the European honey bee (5). As our cities continue to grow and the needs of urban communities become more pressing, this is good news for the virescent green metallic bee and other generalist pollinator species that can benefit from a relatively wide selection of floral resources.

A virescent green metallic bee emerging from a nest. Image from the University of Maine Cooperative Extension.

Having met the virescent green metallic bee for the first time this past summer working with Aaron Anderson on his native plants study at the North Willamette Research and Extension Center, I was curious to see which plants selected for the study had been previously identified as providing forage for the bee. From our list, the common sunflower (Helianthus annuus), yarrow (Achillea millefolium), showy milkweed (Asclepias speciosa), Douglas aster, (Symphyotrichum subspicatus), common camas (Camassia leichtlinii), wild strawberry (Fragraria vesca), Oregon iris (Iris tenax), sedum (Sedum oregonense), and goldenrod (Solidago canadensis) all make the cut (3).

Flowers are important for these bees for more than just food, however; as they also provide a rather scenic backdrop for the crucial business of mating. While female bees will return to the nest after emerging from the incubator cells in the spring, the male bees spend their days foraging, mating, and sleeping out in the cold, eventually dying at the end of the season (4). The females are the real beneficiaries of the underground nests, returning here to hibernate and lay their own eggs, and sharing in the joint responsibilities of guarding and maintaining the tunnels (4).

My favorite green bee may be relatively abundant and may not require as much help as other species in the way of specific planting regimes, but (as with all native ground nesting bees) leaving some undisturbed open space in your yard or garden can go along way to provide habitat. According to the Xerxes Society, nearly 70% of all native bees are ground nesters (6). To offer nesting habitat in your garden, simply leaving a couple feet of well-drained, bare or sparsely vegetated soil available in a sunny location will do (1, 6). The bees will take care of the rest — hopefully you will have the opportunity to enjoy them in your own garden next summer!

Sources:

  1. Moisset, Beatriz, and Stephen Buchmann. “Bee Basics: An Introduction to Our Native Bees.” USDA Forest Service, Mar. 2011.
  2. “Oregon Native Bee Atlas.” Oregon Bee Project, blogs.oregonstate.edu/beeproject/bee-atlas/.
  3. “Agapostemon virescens.” Discover Life, 9 Nov. 2017, www.discoverlife.org/mp/20q?search=Agapostemon%2Bvirescens.
  4. Abrams, Judith, and George C. Eickwort. “Nest switching and guarding by the communal sweat beeAgapostemon virescens (Hymenoptera, Halictidae).” Insectes Sociaux, vol. 28, no. 2, 1981, pp. 105–116., doi:10.1007/bf02223699.
  5. Lowenstein, David M., et al. “Humans, bees, and pollination services in the city: the case of Chicago, IL (USA).” Biodiversity and Conservation, vol. 23, no. 11, Oct. 2014, pp. 2857–2874., doi:10.1007/s10531-014-0752-0.
  6. Shepherd, Matthew. “Nests for Native Bees.” The Xerxes Society for Invertebrate Conservation, 2012.