What are bees doing right now? Spring edition

It’s early spring and the trees have begun leafing out. Colorful flowers are springing from the ground, and the landscape is slowly coming to life with insect activity. In this post, I’ll highlight some of Oregon’s ubiquitous spring bees, what they are up to, and how to easily recognize them.

Graphic by Jen Hayes

Queen bumblebees are emerging from their winter burrows under leaf litter and forest duff. They zoom by with boisterous buzzes. Queen bumblebees are sturdy and furry, and can power through wind, rain and cold better than any other type of bee. Queens are much bigger than the workers that will come once the queens find nest sites and begin laying eggs. For now, they work alone, preparing to lay their first set of worker eggs.

If you see (or hear) any queen bumblebees this spring as they scan the sparsely blooming landscape, they are most likely looking for a proper nest site, finding nectar to energize this search, or, if one has already found her nest, she may be collecting pollen to feed her developing worker offspring.

A rain-drenched Yellow-faced bumble bee on Oregon Grape. Photo by Jen Hayes.
A female mason bee has brought bright yellow pollen to her nest. Video by Jen Hayes.

Mason bees (Osmia lignaria) are a cherished Oregon spring bee active from March to early June. Look closely in a bee hotel for a chance to observe mason bees in action!

Male mason bees emerge first from their pupal cocoons. You might see them patrolling bee hotels waiting for a female to chase down. When the females emerge a little later, they mate and then begin their work provisioning nests with pollen balls and eggs. An individual female has a short lifespan living only about 20 days, but in this time, she may provision anywhere from 2 to 7 nest holes each containing many offspring cells.1 Quite the busy bee!

Andrena is a genus of mining bees that are some of the earliest risers when it comes to spring emergence. They are a diverse group of small, furry, ground-nesting bees that are only active for a few weeks out of the year. Andrena are solitary bees, but can be seen foraging and mating in droves on early blooming fruit trees like cherry, apple and pear. Last spring, I watched hundreds swarm this cherry tree to collect nectar and mate.

Spring Bee Quick ID:

Now, let’s identify some of the bees you may see out and about on sunny spring days when the wind is low. We’ll start with the most conspicuous group – the bumblebees. Bumblebees are the biggest and the loudest bees on the landscape, covered in a thick coat of fuzz. Here’s how to recognize the 3 most common species of bumblebees you’ll see in the Willamette Valley in early spring.

Bombus vosnesenskii or the “yellow-faced bumblebee” is by far the most common bumblebee in this region. It is recognized by the yellow fuzz on its face and yellow band near the distal end of its abdomen.

B. vosnesenskii foraging on butterfly bush. Photo by Mallory Mead.
B. melanopygus queen foraging on Wartleaf Ceanothus. Photo by Mallory Mead.

Bombus melanopygus, the “black-tailed bumble bee” is another of the earliest Bombus species to emerge. You can identify this bee by the orange band in the middle section of its abdomen!

Bombus mixtus, the “fuzzy-horned bumblebee”, tends to emerge a little later than the previous two species, and has orange hair on its lowest abdominal segments.

B. mixtus flies amid borage plant. Photo by Mallory Mead.

Mason bees can be recognized by their deep iridescent blue-green color, that sparkles in the sun. Males are distinguished from females by their small size and the yellow mustaches found on the front of their faces. Females lack the yellow tufts and are larger than the males but smaller than a honey bee. They carry pollen on the underside of their abdomen which is a trait unique to their bee family, Megachilidae.

Female mason bee. Photo by Jen Hayes.
Male mason bee. Photo by Mallory Mead.

Andrena are a diverse group that are tricky to identify. They can be distinguished from other small, furry bees by the presence of velvety hairs between their eyes and the middle of their face called “facial fovea”.2

Pollen on Andrena bee. Photo by © vespidmacro, some rights reserved (CC-BY-NC)

Facial Fovea. Photo from the ODA Bee Guide

They also carry pollen on their hind legs and on hairs between their abdomen and thorax, which distinguish them from bees in the Megachilidae family.

We hope this little guide will help you experience the native bees in your landscape this spring that make the pollen go round.

Thank you for joining us on this exploration of Oregon’s spring bees and what they are currently doing! We will release two 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!

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 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 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 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 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.

Top 10 Oregon Native Plants for Pollinators: Week 1

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

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 1! Profiles will include photos, planting information, and will highlight common pollinators of each plant.

Plant Facts

  • Scientific Name: Achillea millefolium
  • Life Cycle: Perennial
  • Growth Habit: Upright, spreading
  • Bloom Duration: June – October
  • Hardiness Zone: 3-7
  • Special Traits: Drought tolerant, deer resistant
  • When to plant: Starts can be planted in the spring or fall.

Pollinator Facts

  • Yarrow provides both nectar and pollen to its insect visitors.
  • Yarrow was found to be associated with two species of Andrena in Aaron’s research (Andrena cerasifolii, A. candida).
  • Andrena is a genus of early summer mining bees!
  • Other common visitors to yarrow include sweat bees, nomad bees, and butterflies!
  • Yarrow inflorescences provide a great “landing pad” for pollinators- they can rest directly on the plant while they forage.

Yarrow’s Native Range in Oregon

In Oregon, we have our own native variety of yarrow: Achillea millefolium var. occidentalis. 

Western yarrow's native range covers the entire state of Oregon.

Map acquired from USDA Plants Database. Copyright 2014 © ESRI

Yarrow as a pollinator plant

Yarrow is a ubiquitous North American native plant: its range extends from Alaska to Florida and every state and province in between! Though it commonly appears on pollinator planting lists, many people are not convinced that it’s a great bee plant, because it is not typically buzzing with activity like we may see on Goldenrod or Douglas Aster. Instead of hosting an abundance of visitors, yarrow supports a high diversity of insect visitors.

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 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.

Although yarrow doesn’t buzz with activity like some pollinator plants, it’s certainly not a flower to ignore! Yarrow is a hardy and low maintenance perennial that establishes and spreads readily in gardens. It’s a beautiful cut flower and can also be dried to include in longer lasting floral arrangements; its foliage that maintains its aromatic scent even after drying. Yarrow is additionally a wonderful plant medicine that has been used for centuries.

Did you know?

Yarrow has naturally-occurring pink variants! It can vary from pale pink (left), to deeply magenta (right). These plants were started from seeds collected from wild populations of yarrow, so we can be certain it is indeed a natural variation, rather than a true hybrid or cultivar!

Another fun fact: "millefolium" translates to "thousand-leaved", which is a reference to its dissected leaves!

Photos from the field

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