What are bees doing right now? Winter Edition ❄️.

Welcome to the Garden Ecology Lab’s “What are the bees doing” mini-series! This series will extend through the four seasons to shed some light on where bees are in their life cycle and what they may be doing during each of the four seasons. We begin with winter, and an overview of the overwintering and nesting strategies of common groups of bees in the Pacific Northwest.

Graphic by Jen Hayes

As the seasons change, where do all the bees go? Different groups of bees utilize unique strategies to survive the cold of winter. In many cases, bees require cold temperatures to develop properly, and as spring rolls around, they rely on thermal cues to determine when to start their next phase of life.

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We can divide bees into four broad categories based on their strategy to nest and survive the winter. There are the Ground Nesters – who find or dig in the ground to nest and lay eggs, Cavity Nesters – who nest in hollow reeds, canes, or in people’s backyard “bee hotels”, Bumblebees – whose new-born queens burrow into leaf litter, waiting to start a colony in spring…. and then there is the oddball: the European Honey Bees, who are not native to North America, but were brought here along with European colonizers and are now key players in modern agriculture. They do things pretty differently than our native bees, so we’ll start our discussion with them.

The European Honey Bee

European honey bees (Apis mellifera) survive the winter huddling in their hive! They are an example of a social insect and many consider a honey bee hive a superorganism. Fueled by their honey stores, the colony huddles together in a mass to thermoregulate at temperatures between 33 – 36°C (91.4 – 96.8°F).1 I love these words from the American Bee Journal:

 "The honey bee is a cold blooded insect; but the honey bee colony is a warm blooded creature."1

We will see that honey bees are the only bee in our landscape to overwinter socially. The rest go it alone.

Bumblebees

A Bombus californicus queen on Comfrey (Symphytum sp.) in early Spring. Photo by Mallory Mead.

Bumblebees are social bees too, living in natural cavities most often in the ground, but in winter, the members of the colony die off except for the new-born queens. These queens will fly out of the hive on her maiden voyage to mate with a male bumblebee before finding a place to settle and overwinter alone.

Queens find a safe environment often a few inches deep under leaf litter or light soil. As temperatures decrease in Fall and early Winter, the queens do not thermoregulate. Instead, they enter diapause, which is a state of arrested development. An overwintering queen appears frozen in the soil until warmer temperatures wake her again. In the late Winter or Spring she will begin looking for a site to start her own colony.

Cavity Nesting Bees

About 30% of native bees are cavity nesters who build their nests inside cavities in wood or reeds.2 These bees avoid overwintering as adults, and instead, they lay their eggs in cavities and die before the winter temperatures come.

Female cavity nesting bees forage for pollen and nectar and nesting materials in the spring or summer and make balls of pollen and nectar (often called “bee bread”) as food for their offspring!

They lay eggs on the pollen balls, and then proceed to seal off compartments, one for each of the eggs, until the cavity nest is full. These eggs will hatch into larvae that consume the bee bread as winter approaches.

Bee nests in bamboo sticks, indicated by the mud caps at the front of the stakes. Photo by Gail Langellotto
Video by Oliva Honigman.

Here is a video of a small carpenter bee larva eating its bee bread, magnified under a microscope!

Once the larvae finish off their food store, they may spin themselves a cocoon in which they further develop into pupae. Cavity nesters spend the winter developing from pupae to young adults in their cocoons. These developing bees go into a state called torpor to survive the winter, where the bee is inactive and its body temperature drops, but it still goes through critical physiological processes and development.

These bees must experience low Winter temperatures natural to their region to undergo proper development. Mason bees, for example, have lower survival and vital rates when exposed to warm nest temperatures that simulate predicted climate change temperatures for their region.3

Empty mason bee cocoons that were removed from cavities for an experiment, and a newly emerged male mason bee. Photo by Mallory Mead.

Mason bees (genus: Osmia) are cavity nesters that have become well known in garden and agriculture circles in recent years, but many other groups of bees fall into this category too including leafcutter bees (family: Megachilidae), small carpenter bees (genus: Ceratina), large carpenter bees (Genus: Xylocopa), and masked bees (family: Colletidae).

SARE has a great resource on identifying which cavity nester might be nesting in your bee hotel!

A friend of the lab, Olivia Honigman, conducted a brief research project on small carpenter bees in Vermont. Here are some photos from her study that showcase a tiny cavity nesting bee, from the genus Ceratina, nesting in raspberry canes.

Ground Nesting Bees

Last but certainly not least are the ground-nesting bees which make up about 70% of native bee species! Bees from the genera Andrena, Lasioglossum, and Halictus fall into this category.4 Ground-nesters have unassuming nests that are hard to spot, but under the soil, they are putting down bee loaves and laying eggs in a compartmentalized fashion, just like cavity-nesters!

Similarly, adult ground-nesters die after they finish provisioning their nests for their offspring. In the winter, the young bees of the new generation are developing from pupae into adults in their underground nests.

Left: exposed soil revealing tiny holes- could these be bee nests? Top right: A ground-nesting bee pokes its head out of its home. Bottom right: The entrance to a ground-nesting bee’s home. Photos by Gail Langellotto.


Although their nests are modest, some of Oregon’s showstopper bees fall in the ground-nesting category, such as the metallic green sweat bees (Agapostemon).

Metallic green sweat bee on a Clarkia flower. Photo by Mallory Mead.

Long-horned bees from the genera Melisoddes and Eucera also flaunt unique forms with noticeably fluffy, feathery hair on their legs they use for collecting massive volumes of pollen!

A female long-horned bee with dense hairs or scopa on her hind legs. Photo by Mallory Mead
This long-horned bee has “pollen pants” Photo by Mallory Mead.

To invite these bees to your garden, leave patches of earth free from wood mulch and instead mulch with compost! To avoid disturbing ground nests, avoid tilling when possible.4

Here is a great resource from the Xerces Society on how to protect pollinators during the Winter months.

Something remarkable about nesting in the ground is that, depending on nesting depth, ground nesters are more buffered from extreme temperatures than honey bees and cavity nesters whose homes may be in the direct sun. This may be a critical difference when it comes to surviving climate change.

Changing Climatic Norms…

With climate change upon us, native bees have experienced warmer than usual winter temperatures. These conditions may be suboptimal for their development and survival and encourage bees to emerge earlier in the season. Cavity and ground nesting bees require low temperatures with which they have evolved to reach physiological benchmarks for their development, and scientists worry that there will be phenological mismatches between plants and their pollinators in which bees emerge at different times than when their optimal food sources are in bloom as plants and insects will experience novel timing of thermal queues under climate change predictions.5

As bees and other pollinators face a multitude of challenges, we should support our local bees and appreciate them while we can!

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Thank you for joining us on this exploration of what bees are doing during the winter! We will release three more blog posts in this series, one for each of the four seasons. Blogs will be posted during their prospective seasons, so be sure to subscribe so you don’t miss the next in the series!

Top 10 Oregon Native Plants for Pollinators: WEEK 10!!

The Garden Ecology Lab’s Pollinator Plant PR Campaign Presents….. Douglas Aster!

The Garden Ecology Lab is releasing a series of plant profiles of the top 10 Oregon native plants for pollinators, based on Aaron Anderson’s 2017-2019 field trials of 23 Oregon native plants. We will feature one plant per week for 10 weeks, this is week 10, which marks the end of our 10-week series! Profiles will include photos, planting information, and will highlight common pollinators of each plant.

Melissodes visits Douglas Aster. Photo by Tyler Spofford.

Plant Facts

  • Scientific Name: Symphyotrichum subspicatum
  • Life Cycle: Perennial
  • Growth Habit: Vigorous spreader, spreads through underground rhizomes
  • Bloom Duration: July-November
  • Hardiness Zone: 6-9
  • Special Traits: Drought tolerant, deer resistant
  • When to plant: Starts can be planted in the spring or early fall.

Pollinator Facts

  • Douglas aster provides both nectar and pollen to its insect visitors.
  • Aaron’s research found three species of long-horned bees (Melissodes robustior, M. lupinus, and M. microstictus) and three species of bees from the family Halictidae (Halictus ligatus, Agapostemon texanus angelicus and A. virescens) to be associated with Douglas aster.
  • Other common visitors to Douglas aster include syrphid flies and northern checkerspot butterflies! Douglas aster may also be a larval host to 8 different month species1.
Photo by © mandamasprime, some rights reserved (CC-BY-NC).

Douglas Aster‘s Native Range in Oregon

Douglas aster is native to Northwestern Oregon and most of the coast.

Maps and legend acquired from the Oregon Flora Project, with Imagery Sourced from Google. Copyright 2022© TerraMetrics

Douglas Aster as a pollinator plant

Douglas aster is native to Western North American with a range extending from Alaska to California. It has an impressive ability to spread and a high volume of flowers that buzz with pollinator activity throughout its long bloom season. Hosting a high abundance and diversity of bee visitors, Douglas aster is a pollinator plant superstar. It is particularly valuable as a late-season pollinator plant, able to provide both nectar and pollen to its visitors when these resources may otherwise be scarce in the landscape.

People often have strong reactions towards Douglas Aster – they either love it, or find it to be “weedy” in appearance. We hope that this highlight may help some people change their opinions about it! We in the Garden Ecology Lab love Douglas Aster for its abundant blooms in varying shades of purple and for its great capacity for supporting wildlife. In the late summer, we love watching the diversity of pollinators bouncing from one flower to the next! Some common visitors to Douglas Aster that we see at Oak Creek Center for Urban Horticulture include bumblebees, green bees, long-horned bees, small sweat bees, and butterflies, including the woodland skipper (pictured below) and the occasional grey hairstreak (Strymon melinus).

Here, we see a woodland skipper (Ochlodes sylvanoides) foraging from Douglas Aster!
Infographics developed by LeAnn Locher, Aaron Anderson, and Gail Langellotto.

Did you know?

By mid to late summer, Douglas aster is quite the frenzied pollinator feeding ground, making the Oak Creek team’s sampling effort always a bit of a challenge. These photos are from 2 years after these plants were established, so you can see just how full these young plants can get when grown in favorable conditions!

At Oak Creek, we started all of our Douglas Aster plots with 4x 4″ pots, planted in the spring of 2020. As you can see in the photos below, they easily filled up their 1×1 meter beds! If you’re worried about Douglas Aster taking over your garden, consider starting with a single plant and observe it over the season to see how it reacts to your garden environment. Aggressive spreaders can be used to fill spaces such as borders with forest edges or along fences where low maintenance plants are key. If you want to contain your asters, consider planting some in a large pot or in an area where you can easily control the spread of their underground rhizomes. The purple flowers contrast beautifully with other late season natives, such as goldenrod and Madia.

Jen standing next to her Douglas Aster experimental plots. Photo by Tyler Spofford.
Tyler vacuum sampling bees off of a Douglas Aster plot. Photo by Jen Hayes.

Photos from the field

Thanks for tuning in to the last posting of our Pollinator Plant PR Campaign! We hope you try growing some of these fantastic pollinators plants.

Top 10 Oregon Native Plants for Pollinators: Week 9

The Garden Ecology Lab’s Pollinator Plant PR Campaign Presents….. California Poppy!

The Garden Ecology Lab is releasing a series of plant profiles of the top 10 Oregon native plants for pollinators, based on Aaron Anderson’s 2017-2019 field trials of 23 Oregon native plants. We will feature one plant per week for 10 weeks, this is week 9! Profiles will include photos, planting information, and will highlight common pollinators of each plant.

Photo by Jen Hayes

Plant Facts

  • Scientific Name: Eschscholzia californica
  • Life Cycle: Annual/Perennial
  • Growth Habit: Clumping, sprawling
  • Bloom Duration: Early Spring to Late Summer depending on seeding date.
  • Hardiness Zone: 7-10
  • Special Traits: Drought-tolerant, deer and rabbit resistant.
  • When to plant: Seed in Fall for a Spring bloom, or seed in Spring for a mid-summer bloom.

Pollinator Facts

  • California poppy only provides pollen to its insect visitors, but provides it in an abundance!
  • Aaron’s study found California poppy to be associated with 4 species of sweat bees: Halictus farinosus, H. tripartitus, Lasioglossum dialictus sp. 5, L. olympiae, and a bumblebee: Bombus vosnesenskii.
  • Other common visitors to California poppy include butterflies, specifically, acmon blue and mormon metalmark.

Sweat bee leaving a California poppy. Photo by Jen Hayes

California Poppy’s Native Range in Oregon

Oregon's populations of California poppy are primarily found in the Willamette Valley and the Klamath Mountains as well as some parts of the Columbia River Gorge and the Coast Range.

Maps and legend acquired from the Oregon Flora Project, with Imagery Sourced from Google. Copyright 2021© TerraMetrics

California poppy as a pollinator plant

California poppy’s range extends from Washington to northwest Baja California and east towards Arizona and southwest New Mexico. A popular flower for roadside plantings, California poppy survives well in average to poor soil that is well-draining. It survives mild-winters as an herbaceous perennial and reseeds itself readily. California poppy is an all-around easy pollinator plant to grow, and growing it pays off, as it attracts an incredible diversity and abundance of bees with its remarkable volumes of pollen.

Infographics developed by LeAnn Locher, Aaron Anderson, and Gail Langellotto.

Did you know?

California poppy’s petals are responsive to light! In the absence of light (at night and on cloudy days) petals spiral around each other and tighten to a close. In the presence of light, cells in the petals expand in response to the plant growth hormone auxin. This mechanism opens the petals allowing pollinators to access the flower’s pollen — although in the field we watch impatient bumblebees force their way into closed California poppy flowers to get to the pollen anyways.

Petals close tight during the night and remain so on overcast days. Photo by iNaturalist user metacom CC some rights reserved
Poppies in various stages of opening and poppy buds enclosed in pinkish-green calyxes. Photo by iNaturalist user Daniel Das CC some rights reserved

Photos from the field

Tune in next week for the next edition of our Pollinator Plant PR Campaign.

Top 10 Oregon Native Plants for Pollinators: Week 8

The Garden Ecology Lab’s Pollinator Plant PR Campaign Presents….. Globe Gilia!

The Garden Ecology Lab is releasing a series of plant profiles of the top 10 Oregon native plants for pollinators, based on Aaron Anderson’s 2017-2019 field trials of 23 Oregon native plants. We will feature one plant per week for 10 weeks, this is week 8! Profiles will include photos, planting information, and will highlight common pollinators of each plant.

Photo by iNaturalist user © slewiiis,
 some rights reserved

Plant Facts

  • Scientific Name: Gilia capitata
  • Life Cycle: Annual
  • Growth Habit: Erect, clusters
  • Bloom Duration: May – June
  • Hardiness Zone: 7-10
  • Light requirements: full sun
  • Special Traits: Drought tolerant, tolerant to various soil types.
  • When to plant: Seeds can be sewn directly in the fall, or can be stratified indoors over the winter before planting out in the spring.

Pollinator Facts

  • Globe Gilia provides both nectar and pollen to its insect visitors.
  • Gilia was found to be associated with the yellow-faced bumble bee, Bombus vosnesenskii in Aaron’s research.
  • Globe Gilia is also a larval host for at least one moth species, Adela singulella, but possibly four others as well.
  • In addition to insect visitors, Gilia is can be an occasional nectar source for hummingbirds1, which love its tubular flowers!

Photo by iNaturalist user © mudcitymelissa,
 some rights reserved

Globe Gilia‘s Native Range in Oregon

There are three subspecies of Gilia capitata in Oregon: Bluefield Gilia (ssp. capitata), Dune Gilia (ssp. chamissonis), and Pacific Gilia (ssp. pacifica). Dune Gilia and Pacific Gilia are considered to be rare plants in California (rare, threated, or endangered, rank 1B).

Distribution maps acquired from Oregon Flora with imagery from Google. Copyright 2022.

Globe Gilia as a pollinator plant

Globe Gilia may have only been associated with a single bee species in Aaron’s native plant research, but it is truly a powerhouse of an annual plant: it supports a highly diverse and abundant community of native bees! Gilia’s globe of flower heads provide pollinators with plenty of foraging spots to choose from, and the dense mass also allows easy access for both small and large pollinators, by acting as a nice landing pad. From their comfortable perch, butterflies and larger-bodied bees can dip their proboscis (tongue) into the nectar-rich blossoms. Smaller bees may need to crawl in to the individual flowers to access the nectaries.

Gilia is a great annual plant option to include in pollinator mixes and in meadows. It’s an easy to care for plant, requiring minimal water during the growing season. It grows up to three feet in height with lovely lavender – dark purple – blue flower heads, lacy foliage, and surprising blue pollen! The flowers contrast wonderfully with many other mid-summer blooms, such as poppies, Oregon sunshine, asters, and Clarkia.


Infographics developed by LeAnn Locher, Aaron Anderson, and Gail Langellotto.

Abundance Calculations. Bee abundance was calculated using estimated marginal means of bee visitation to each of our study plants from 5-minute observations conducted from Aaron’s 2017-2019 field seasons. Estimated marginal means (EM Means) were assigned to categorical values and averaged across years to yield the following categories: 0% = Very Low =EM mean below 0.49; 25% = Low = EM mean of 0.50 to 0.99; 50% = Moderate = EM mean of 1 to 1.49; 75% = High = EM mean of 1.50 to 1.99; and 100% = Very high = EM mean above 2.0.

Diversity Calculations. Bee diversity was based on the total sum of species collected on each of our study plants from 2017 to 2019. A Chao 2 Estimator was used to estimate total expected species richness for each plant; Chao 2 estimates were then used to create categorical values, as follows: 0% = Very Low = 9.99 or lower; 25% = Low = 10 to 14.99; 50% = Moderate = 15 to 19.99; 75% = High = 20 to 24.99; 100% = Very high = 25 or higher.


Did you know?

When you think about pollen, one color tends to come to mind: yellow. Perhaps you conjure up an image of a bumblebee in a field of clover, weighed down by some giant orange-toned pollen baskets as well. Many of us might stop there, and conclude that pollen must be either yellow or orange, as those are the predominant pollen colors we see in the plant world. The absolutely exciting news is that, like flower colors, pollen also comes in a rainbow of colors. Globe Gilia, for example, has pollen that comes in shades of blue!

A spotlight on pollen colors

As some of you may remember from my (Jen’s) 2021 field update, last summer, a few of us from the Garden Ecology lab had the wonderful opportunity to visit Jasna Guy and Lincoln Best’s exhibit ‘In Time’s Humm’ at the High Desert Museum in Bend. Part of this display was a pollen color study, showing Jasna’s recreations of pollen colors using pastels. We saw pollen in shades of yellows, oranges, red, pink, purple, white, and even green. Color can truly be found anywhere if you look closely enough! Perhaps it should be no surprise then, that even nectar may come in various colors, too… If you’re excited about pollen colors like we are, you might see if your local library has a copy of this book, and you might enjoy looking at pollen colors through the seasons, put together by the North Shropshire Beekeepers’ Association.

Now back to Globe Gilia: Photos from the field

Tune in next week for the next edition of our Pollinator Plant PR Campaign.

3 Ways to Help Pollinators During Winter

I’m sure many are familiar with the long treks that many pollinators make when winter begins to roll around. Monarch butterflies will travel thousands of miles to reach their final destination. Rufous hummingbirds will spend August swooping and diving in your backyards before moving Southward as September slowly drizzles it’s way into October. But not every pollinator decides to seek warmer climes as the temperature drops. Many opt to hunker down and wait out the cold weather, seeking shelter in any manner of burrow all around your gardens. This post is focused on several things that you, as caretakers of your gardens and friends of pollinators, can do to watch out for your hard working friends. 

Photo: Steven Severinghaus / Flickr Creative Commons 2.0
  1. Leave the leaves

One of the most important things you can do to help overwintering pollinators is by doing nothing at all. By leaving the ground cover of leaves, sticks, and plant material you are also leaving the material that many pollinators use to make nests. Many pollinators will snuggle down into this protective layer, and be safe and sound during the colder months. By not raking up the leaves deposited by shedding trees, you are helping pollinators have a safer and more comfortable winter. If a little clean up is necessary, try not to completely remove the leaves or plant material, but instead, rake it onto beds or around shrubs so that it stays as part of the environment. Along with protecting pollinators, leaving this cover can help retain soil moisture, prevent weeds, return nutrients to the soil, and reduce waste entering landfills. So if and when possible, consider leaving the leaves. 

Pale Swallowtails overwinter in Central Oregon during the chrysalis stage of life. Photo: Steve Pedersen. 
  1. Postpone pulling up dead stems, or moving old bark 

Many pollinators will use dead stems or old bark as protection from the elements while they are overwintering. If possible, postpone pulling dead steams, or throwing out old branches, sticks or bark. Cavity dwelling pollinators will often seek shelter inside wood piles, old logs, or dead flower stalks. Several types of chrysalis’s have patterns similar to wood to blend into the environment while the pupa inside waits for spring. Butterflies that do not migrate will spend winter in varying life stages, some as eggs, some as caterpillars, some as a chrysalis, and some as adults. Therefore, it is best to leave as many forms of shelter as possible. Keep your eye on any bamboo posts in your garden, as many different types of bees will use these as bunkers during the cold. Be careful when moving or uprooting, and keep an eye out for pollinators hiding in crevices, cracks or crannies.

Photo by Kyle Blaney
  1. Leave your hummingbird feeder up

There are many different opinions on this advice. Many people will say that leaving your hummingbird feeder up during the winter will deter the hummingbirds from migrating. However, there is no easily found evidence that supports this. The Audubon Organization indicates that you can leave up your feeder for as long as you have hummingbirds, and having a feeder up as winter rolls around will not keep hummingbirds from migrating. Hummingbirds migrate due to genetics and other factors, not necessarily due to availability of food. However, not all hummingbirds migrate. Anna’s hummingbird, which can be found across the Northwest, Oregon included, is nonmigratory, and might be extra appreciative of feeders that are left up during the colder months. Adding extra sugar to keep the hummingbird food from freezing is not recommended, however, as this can dehydrate the birds. Keep the ratio of 1:4 parts sugar to water. Instead, to try and prevent freezing, you can take the feeder inside at night; hummingbirds don’t feed at night. You can also hang an incandescent bulb near the feeder, as this can generate enough heat to keep the feeder thawed. 

While the three listed above are only a few steps to be taken to help overwintering pollinators, a little help can go a long way for our essential pollinator companions. They, like any of us, just want to stay warm and fed during the cold months, and I’m sure would greatly appreciate any help from you in helping them stay that way.

Top 10 Oregon Native Plants for Pollinators: Week 7

The Garden Ecology Lab’s Pollinator Plant PR Campaign Presents….. Farewell-to-Spring!

The Garden Ecology Lab is releasing a series of plant profiles of the top 10 Oregon native plants for pollinators, based on Aaron Anderson’s 2017-2019 field trials of 23 Oregon native plants. We will feature one plant per week for 10 weeks, this is week 7! Profiles will include photos, planting information, and will highlight common pollinators of each plant.

Photo by Jen Hayes.

Plant Facts

  • Scientific Name: Clarkia amoena
  • Life Cycle: Annual
  • Growth Habit: Upright, clumping
  • Bloom Duration: June – September
  • Hardiness Zone: 1-11
  • Special Traits: Drought tolerant, deer resistant
  • When to plant: For best results, direct seed in Fall or early Spring. Seeds can also be sown in containers or cold frames in the winter.

Pollinator Facts

  • Farewell-to-Spring was found to be associated with Megachile brevis, a species of leafcutter bee.
  • Other common bee visitors include long-horned bees of the genus Eucerini and other species of leafcutter bees.
  • Farewell-to-Spring also hosts some butterflies and moths including the White-Lined Sphinx, Pacific Green Sphinx Moth, and Clark’s Day Sphinx Moth.
  • Farewell-to-Spring provides both nectar and pollen to its insect visitors.
  • Although pollen is easily accessed on the protruding stamen, bees must dive into the flower to reach the nectar that is produced beneath the petals. This is because nectar is produced at the base of the ovary, and Farewell-to-Spring has an “inferior ovary” meaning the ovary is positioned below the sepals and petals.

A male bumble bee dives into a Farewell-to-Spring flower to reach its nectar. Photo by Jen Hayes.
Farewell-to-Spring’s nectaries are found beneath the stamen and petals. Photo © Stephanie Hazen.
 some rights reserved

Farewell-to-Spring’s Native Range in Oregon

Farewell-to-Spring is found throughout Western Oregon from the Coast through the Cascades. Oregon is home to 4 subspecies of Clarkia amoena.

Maps and legend acquired from the Oregon Flora Project, with Imagery Sourced from Google. Copyright 2021© TerraMetrics

Farewell-to-Spring as a pollinator plant

Farewell-to-Spring hosts a moderate abundance of bee visitors, but the diversity of bees it hosts is among the highest found in the study! With a long flowering season, Farewell-to-Spring blooms when spring wildflowers are beginning to turn brown. Bloom duration can be lengthened by occasional watering over the summer, although Farewell-to-Spring are drought-tolerant and survive with minimal summer irrigation. This flower is an annual, but will reseed itself readily.

Infographics developed by LeAnn Locher, Aaron Anderson, and Gail Langellotto.

Abundance Calculations. Bee abundance was calculated using estimated marginal means of bee visitation to each of our study plants from 5-minute observations conducted from Aaron’s 2017-2019 field seasons. Estimated marginal means (EM Means) were assigned to categorical values and averaged across years to yield the following categories: 0% = Very Low =EM mean below 0.49; 25% = Low = EM mean of 0.50 to 0.99; 50% = Moderate = EM mean of 1 to 1.49; 75% = High = EM mean of 1.50 to 1.99; and 100% = Very high = EM mean above 2.0.

Diversity Calculations. Bee diversity was based on the total sum of species collected on each of our study plants from 2017 to 2019. A Chao 2 Estimator was used to estimate total expected species richness for each plant; Chao 2 estimates were then used to create categorical values, as follows: 0% = Very Low = 9.99 or lower; 25% = Low = 10 to 14.99; 50% = Moderate = 15 to 19.99; 75% = High = 20 to 24.99; 100% = Very high = 25 or higher.


Did you know?

Leaf cutters forage for pollen, nectar, and one more surprising resource: petal clippings! Using their mandibles, the bees cut out a piece of a petal (often in the shape of a crescent), clasp the piece of petal under their abdomens, and fly away to use the petal as building material in their nests. If you keep a mason bee or leafcutter bee house in your yard and grow Farewell-to-Spring, look for nest holes that are plugged with pink petals instead of mud or leaves.

The tips of some of this flower’s petals have been harvested from by leafcutter bees:


Leafcutters in Action

In each of Jen’s two field seasons, she has set a challenge for student technicians: obtain a video of a leafcutter harvesting a piece of petal from Clarkia. Students that win the challenge are rewarded with baked goods!! This past summer, Mallory succeeded in capturing not one, but two videos of leafcutters in action (below). Leafcutters can be particularly difficult to capture on video because they cut the petal pieces very quickly, and often fly even faster! If you have Clarkia growing in your garden, look to see if your flowers bear any crescent-shaped cuts. If they do, you too might be able to spot some special bees flying away with their floral confetti.

Videos by Mallory Mead, summer 2021.

Photos from the field

Tune in next week for the next edition of our Pollinator Plant PR Campaign.

Top 10 Oregon Native Plants for Pollinators: Week 6

The Garden Ecology Lab’s Pollinator Plant PR Campaign Presents….. Common Madia (AKA Tarweed)!

The Garden Ecology Lab is releasing a series of plant profiles of the top 10 Oregon native plants for pollinators, based on Aaron Anderson’s 2017-2019 field trials of 23 Oregon native plants. We will feature one plant per week for 10 weeks, this is week 6! Profiles will include photos, planting information, and will highlight common pollinators of each plant.

Photo © Rob Irwin
 some rights reserved

Plant Facts

  • Scientific Name: Madia elegans
  • Life Cycle: Annual
  • Growth Habit: Erect, slender
  • Bloom Duration: July – September
  • Hardiness Zone: 1-11
  • Light requirements: Prefers full sun, will tolerate partial shade.
  • Special Traits: Drought tolerant, deer resistant, seeds valued by birds, adaptable to many soil types and textures.
  • When to plant: Seeds can be sown directly in the fall, or sown in containers or cold frames in the winter. Stratify seeds if growing indoors.

Pollinator Facts

  • Common madia provides both nectar and pollen to its insect visitors and blooms during a period where foraging resources are often scarce (late summer – early fall).
  • Madia was found to be associated with two bee species in Aaron’s research: the Bi-colored Sweat Bee (Agapostemon virescens) and Titus’s Sweat Bee (Lasioglossum titusi)
  • Madia is also the larval host for three moth species: the Spotted Straw Sun Moth (Heliothis phloxiphada), the Small Heliothodes Moth (Heliothodes diminutivus), and an Epiblema moth (Epiblema deverrae)1.

Photo © Chris Cameron
 some rights reserved

Common Madia‘s Native Range in Oregon

Madia elegans is native to most of Western Oregon. Although it's native range does not extend east of the Cascades, it is a hardy annual that may do well in Central- and Eastern- Oregon gardens.

Map acquired from Oregon Flora with imagery sourced from Google.

Common Madia as a pollinator plant

Common Madia is an ideal plant for pollinator gardens due to its long bloom duration and attractiveness to bees, caterpillars, and butterflies. Madia was found to attract both a high abundance and a high diversity of bee visitors, which further speaks to its use as a great pollinator plant! Due to it’s late-summer bloom period, Madia can act as a great source of forage for it’s various visitors when there may not be many other plants flowering in the landscape. Madia flowers, which close at dusk and reopen in the morning, may also come with a fun surprise if you catch them before the sun has finished its ascent: if you’re lucky, you may be able to find male long-horned-bees sleeping in groups within the flowers2.


Infographics developed by LeAnn Locher, Aaron Anderson, and Gail Langellotto.

Abundance Calculations. Bee abundance was calculated using estimated marginal means of bee visitation to each of our study plants from 5-minute observations conducted from Aaron’s 2017-2019 field seasons. Estimated marginal means (EM Means) were assigned to categorical values and averaged across years to yield the following categories: 0% = Very Low =EM mean below 0.49; 25% = Low = EM mean of 0.50 to 0.99; 50% = Moderate = EM mean of 1 to 1.49; 75% = High = EM mean of 1.50 to 1.99; and 100% = Very high = EM mean above 2.0.

Diversity Calculations. Bee diversity was based on the total sum of species collected on each of our study plants from 2017 to 2019. A Chao 2 Estimator was used to estimate total expected species richness for each plant; Chao 2 estimates were then used to create categorical values, as follows: 0% = Very Low = 9.99 or lower; 25% = Low = 10 to 14.99; 50% = Moderate = 15 to 19.99; 75% = High = 20 to 24.99; 100% = Very high = 25 or higher.


A syrphid fly visiting a Madia flower. Photo by Signe Danler.

Did you know?

The other common name for Madia, “Tarweed”, comes from its foliage. It’s covered in stiff trichomes (hairs) and stalked glands which emit a tar-like scent. Common Madia is not the only species with this nickname, it applies to plants in the entire genus! For example, Madia glomerata, “Mountain Tarplant”, is a species of Madia native to the Northeast United States.

Common Madia‘s fruits are flattened achenes, which are valued by small mammals and birds as a food source. The achenes were also used by Indigenous groups, including the Pomo, Miwok, and Hupa and as a staple food source3. The fruits were often roasted with hot coals and then ground into flour.

Photos from the field

Tune in next week for the next edition of our Pollinator Plant PR Campaign.

Top 10 Oregon Native Plants for Pollinators: Week 5

The Garden Ecology Lab’s Pollinator Plant PR Campaign Presents….. Canada Goldenrod!

The Garden Ecology Lab is releasing a series of plant profiles of the top 10 Oregon native plants for pollinators, based on Aaron Anderson’s 2017-2019 field trials of 23 Oregon native plants. We will feature one plant per week for 10 weeks, this is week 5! Profiles will include photos, planting information, and will highlight common pollinators of each plant.

Photo by iNaturalist user jessdraws.
no rights reserved (CCO).

Plant Facts

  • Scientific Name: Solidago canadensis*
  • Life Cycle: Perennial
  • Growth Habit: Erect, arching
  • Bloom Duration: July-October
  • Hardiness Zone: 3-9
  • Special Traits: Moderately drought tolerant, deer and rabbit resistant
  • Light requirements: Prefers full sun, but tolerates some shade.
  • When to plant: Plant starts in the Spring, or sow seeds directly in the Fall.

Pollinator Facts

  • Canada goldenrod provides both nectar and pollen to its insect visitors.
  • In Aaron’s research, Canada goldenrod was found to be associated with a species of long horned bee, Melisoddes microstictus and bees from the genus Bombus (bumblebees).
  • Other common visitors to Canada goldenrod are Northern Checkerspot butterflies, Field Crescent butterflies, Wavy-Lined moths, and Common Grey moths.
Bumble bee visiting Canada Goldenrod. Photo by Signe Danler

*A Note on Taxonomy

Canada goldenrod is often treated as a complex, or group of species, under the scientific name Solidago canadensis. In western North America, the complex includes S. elongata, S. lepida, and S. altissima. Tall goldenrod, S. altissima, is not native to Oregon, so when we refer to Solidago canadensis in Oregon, this only includes S. lepida “Cascade Canada Goldenrod” and S. elongata “Western Goldenrod”.

Goldenrods (the genus Solidago) are known to be a very difficult plant to identify to species, because they have a great amount of variation in their morphology within even a single species. To avoid any concerns about what species you’re getting when sourcing goldenrod or other native plants, we highly recommend purchasing plants from a local native plant nursery or grower that sources their seeds within your region!

Canada Goldenrod’s Native Range in Oregon

Oregon is home to Solidago lepida "Cascade Canada Goldenrod" and Solidago elongata, "Western Canada Goldenrod". Both of these species are found throughout Oregon, though they were previously thought to be geographically distinct.

Maps and legend acquired from the Oregon Flora Project, with Imagery Sourced from Google.

Canada Goldenrod as a pollinator plant

Canada goldenrod grows in prairies, meadows and riparian areas across Canada and the United States. Great for erosion control, hedgerows and pollinator gardens, Canada goldenrod will fill space with hardy foliage year round and present a showy display of golden flowers in the late summer. The pyramidal inflorescences are lined with tiny composite flowers that brim with nectar and pollen. Goldenrod supports many late season butterflies, moths, bees, beetles and some wasps.

Goldenrod is a wonderful late-flowering plant for pollinators; it hosts a moderate abundance and a high diversity of insect visitors. During its peak bloom, you can often find numerous different insects foraging on goldenrod. We love combining goldenrod with Douglas aster for a beautiful late-season floral display of yellow and purple, though it also compliments shorter annual species as well.

Infographics developed by LeAnn Locher, Aaron Anderson, and Gail Langellotto.

Abundance and Diversity Calculations. Bee abundance was calculated using estimated marginal means of bee visitation to each of our study plants from 5-minute observations conducted from Aaron’s 2017-2019 field seasons. Estimated marginal means (EM Means) were assigned to categorical values and averaged across years to yield the following categories: 0% = Very Low =EM mean below 0.49; 25% = Low = EM mean of 0.50 to 0.99; 50% = Moderate = EM mean of 1 to 1.49; 75% = High = EM mean of 1.50 to 1.99; and 100% = Very high = EM mean above 2.0.

Bee diversity was based on the total sum of species collected on each of our study plants from 2017 to 2019. A Chao 2 Estimator was used to estimate total expected species richness for each plant; Chao 2 estimates were then used to create categorical values, as follows: 0% = Very Low = 9.99 or lower; 25% = Low = 10 to 14.99; 50% = Moderate = 15 to 19.99; 75% = High = 20 to 24.99; 100% = Very high = 25 or higher.

Did you know?

Although this goldenrod is often blamed for people’s late summer allergies, the culprit is in fact ragweed! Ragweed and goldenrod have different pollination styles: ragweed produces masses of airborne pollen in an attempt to reach other ragweed plants by wind. Since goldenrod has evolved with pollinators to carry its pollen in a targeted fashion, goldenrod produces less pollen, very little of which is airborne.

Canada goldenrod has additionally been used as a plant medicine in many cultures; it was used as a substitute for English tea during the American Revolution for its pain-relieving and diuretic effects. Goldenrod flowers are edible and make a colorful garnish that make a beautiful addition to garden salads.

Photos from the field

Tune in next week for the next edition of our Pollinator Plant PR Campaign.

Top 10 Oregon Native Plants for Pollinators: Week 4

The Garden Ecology Lab’s Pollinator Plant PR Campaign Presents….. Varileaf Phacelia!

The Garden Ecology Lab is releasing a series of plant profiles of the top 10 Oregon native plants for pollinators, based on Aaron Anderson’s 2017-2019 field trials of 23 Oregon native plants. We will feature one plant per week for 10 weeks, this is week 4! Profiles will include photos, planting information, and will highlight common pollinators of each plant.

Photo by iNaturalist user Leslie Flint.
CC Some rights reserved.

Plant Facts

  • Scientific Name: Phacelia heterophylla
  • Life Cycle: Biennial/ annual, typically grown as an annual in Oregon
  • Growth Habit: Upright, mounding
  • Bloom Duration: April – July
  • Hardiness Zone: 3-7
  • Special Traits: Shade tolerant, drought tolerant
  • Light requirements: Full sun to part shade
  • When to plant: Seeds should be sown in the fall, starts may be planted in the fall or spring after the last chance of frost.

Pollinator Facts

  • Varileaf Phacelia provides both nectar and pollen to its insect visitors.
  • Phacelia was found to be associated with five bee species in Aaron’s research: the obscure bumblebee (Bombus caliginosus), Edward’s long-horned bee (Eucera edwardsii), the fuzzy-horned bumblebee (Bombus mixtus), the confluent miner bee (Panurginus atriceps), and the yellow-faced bumblebee (Bombus vosnesenskii).
  • Phacelia is also a larval host for 4 moths: the Bilobed Looper Moth (Megalographa biloba), the Geranium Plume Moth (Amblyptilia pica), the Orange Tortrix Moth (Argyrotaenia franciscana) and Clepsis fucana1.

Photo by Aaron Anderson

Varileaf Phacelia‘s Native Range in Oregon

Phacelia heterophylla is native to most of the Western United States – From Washington to California, east to Montana and south to New Mexico. It is additionally native to Canada, where it is currently considered “imperiled” by the IUCN red list2.

Varileaf Phacelia's native range covers nearly the entire state of Oregon! It's native habitat includes moist conifer forests, riparian areas, sagebrush, mountain brush, as well as in aspen and fir communities3.
Maps and legend acquired from the Oregon Flora Project, with Imagery Sourced from Google.

Varileaf Phacelia as a pollinator plant

A female long-horned bee (Eucera sp.) searches for some leftover forage on a spent Phacelia heterophylla inflorescence. Photo by Aaron Anderson.

Varileaf Phacelia is the epitome of an underappreciated pollinator plant! This annual with petite white flowers attracts both an abundance and diversity of insect visitors. With stamen that stick out of the corolla, it heavily advertises its nutritious rewards, attracting plenty of busy bees. In fact, it commonly hosted 5 different bee species in Aaron’s field surveys, including three charismatic bumblebee species, one of which is currently listed as “vulnerable” on the IUCN Red List: Bombus caliginosus, the obscure bumblebee4.


Infographics developed by LeAnn Locher, Aaron Anderson, and Gail Langellotto.

Abundance and Diversity Calculations. Bee abundance was calculated using estimated marginal means of bee visitation to each of our study plants from 5-minute observations conducted from Aaron’s 2017-2019 field seasons. Estimated marginal means (EM Means) were assigned to categorical values and averaged across years to yield the following categories: 0% = Very Low =EM mean below 0.49; 25% = Low = EM mean of 0.50 to 0.99; 50% = Moderate = EM mean of 1 to 1.49; 75% = High = EM mean of 1.50 to 1.99; and 100% = Very high = EM mean above 2.0.

Bee diversity was based on the total sum of species collected on each of our study plants from 2017 to 2019. A Chao 2 Estimator was used to estimate total expected species richness for each plant; Chao 2 estimates were then used to create categorical values, as follows: 0% = Very Low = 9.99 or lower; 25% = Low = 10 to 14.99; 50% = Moderate = 15 to 19.99; 75% = High = 20 to 24.99; 100% = Very high = 25 or higher.


In a survey of gardeners conducted by Aaron and the Garden Ecology Lab, Phacelia heterophylla ranked last among 23 native plants scored for their aesthetic appeal. It may appear “weedy” to some gardeners, but as an annual, it could easily be interspersed with more attractive annual face flowers (such as California poppy, meadowfoam, farewell to spring, or baby blue eyes) to create a colorful and nutritious pollinator garden. Varileaf Phacelia is also a great native annual to include in dryland pollinator gardens, considering it is drought tolerant and able to grow in both nutrient poor and rocky soils.

Did you know?

Photo by iNaturalist user jwlipe. CC Some rights reserved.

Varileaf Phacelia also has the common name "Variegate Scorpionweed", and the pictures above can show you exactly why! It's flowers are borne on elongated stems which are tightly curled, similar to a fiddlehead from a fern! The flowers bloom from the base to the apex of the stem, and the "scorpion tail" slowly unravels as the blooms travel up the stem.

Photos from the field

Of all of the plants we highlight in this 10-week series, Varileaf Phacelia is the one plant that Gail regularly says is in great need of it's own public relations (PR) team. The goal of these plant profiles is to share information and photos of these plants that might convince readers to love this plant as much as we (and the bees) do! 

Let us know which plants have caught your eye, or those that may still take some convincing, by leaving a comment below! 🐝

Tune in next week for the next edition of our Pollinator Plant PR Campaign.

Top 10 Oregon Native Plants for Pollinators: Week 3

The Garden Ecology Lab’s Pollinator Plant PR Campaign Presents….. Pearly Everlasting!

The Garden Ecology Lab is releasing a series of plant profiles of the top 10 Oregon native plants for pollinators, based on Aaron Anderson’s 2017-2019 field trials of 23 Oregon native plants. We will feature one plant per week for 10 weeks, this is week 3! Profiles will include photos, planting information, and will highlight common pollinators of each plant.

Photo by Patrick Perish

Plant Facts

  • Scientific Name: Anaphalis margaritacea
  • Life Cycle: Perennial
  • Growth Habit: Upright, clumping
  • Bloom Duration: June – October
  • Hardiness Zone: 3-8
  • Special Traits: Drought tolerant, deer resistant
  • Light requirements: Prefers full sun but will grow in partial shade
  • When to plant: Plant starts in the Spring, or sow seeds directly in the Fall.

Pollinator Facts

  • Pearly everlasting was found to be associated with two species of mining bees in Aaron’s research: Andrena cerasifolii, Andrena candida.
  • Other common visitors to Pearly Everlasting are American Lady butterflies, Painted Lady butterflies, Everlasting Tebenna moth, and Sweat bees.
  • Female and male flowers are generally found on separate Pearly Everlasting plants. This means that male plants provide nectar and pollen to insect visitors while female flowers just provide nectar.
Andrena visiting Pearly Everlasting. Photo by Aaron Anderson

Pearly Everlasting’s Native Range in Oregon

Oregon is home to three varieties of Pearly Everlasting whose native ranges extend the Cascade range, Western Oregon and parts of northeastern Oregon.

Maps and legend acquired from the Oregon Flora Project, with Imagery Sourced from Google. Copyright 2021© TerraMetrics

Pearly Everlasting as a pollinator plant

Pearly Everlasting is an herbaceous perennial commonly seen in open meadows, burned areas, rocky flats and along roadsides in dry, sun-exposed soils. Native throughout the United States, except for the Southwest, Pearly everlasting is an excellent nectar resource for pollinators, and is especially attractive to many butterfly and moth species. It makes an important larval host plant for American Lady and Painted Lady Butterflies whose seasonal feeding can leave Pearly Everlasting foliage slightly tattered, but nothing that the plant can’t recover from.

Pearly Everlasting hosts a moderate abundance and a relatively low diversity of insect visitors, but is a key host plant for its associated pollinators.

Infographics developed by LeAnn Locher, Aaron Anderson, and Gail Langellotto.

Abundance and Diversity Calculations. Bee abundance was calculated using estimated marginal means of bee visitation to each of our study plants from 5-minute observations conducted from Aaron’s 2017-2019 field seasons. Estimated marginal means (EM Means) were assigned to categorical values and averaged across years to yield the following categories: 0% = Very Low =EM mean below 0.49; 25% = Low = EM mean of 0.50 to 0.99; 50% = Moderate = EM mean of 1 to 1.49; 75% = High = EM mean of 1.50 to 1.99; and 100% = Very high = EM mean above 2.0.

Bee diversity was based on the total sum of species collected on each of our study plants from 2017 to 2019. A Chao 2 Estimator was used to estimate total expected species richness for each plant; Chao 2 estimates were then used to create categorical values, as follows: 0% = Very Low = 9.99 or lower; 25% = Low = 10 to 14.99; 50% = Moderate = 15 to 19.99; 75% = High = 20 to 24.99; 100% = Very high = 25 or higher.

Did you know?

As a plant that thrives in high light and very dry conditions, Pearly Everlasting is one of the first plants to colonize recently burned forests. When rain comes after a fire-season, Pearly Everlasting sends out rhizomes that allow the plant to spread rapidly across nutrient-rich areas. Similarly in a garden setting, Pearly Everlasting has low moisture and nutrient needs but when heavily watered and fertilized, it can quickly take over.

Established Pearly Everlasting should not be irrigated more than twice per month in the summer months. The white, petal-like bracts of Pearly Everlasting flowers retain a fresh appearance after being dried, so gardeners that allow aboveground growth to dry out in the summer months will be rewarded with dried flowers perfect for floral arrangements.

Photos from the field

Tune in next week for the next edition of our Pollinator Plant PR Campaign.