Category Archives: Pollinator of the Week

Top 10 Oregon Native Plants for Pollinators: Week 5

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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

  • Cascade Canada Goldenrod
  • Western Canada Goldenrod
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

  • Photo by iNaturalist User craigmartin
  • Photo by iNaturalist User matthias55
  • Photo by iNaturalist User crwrcwamt
  • Photo by iNaturalist User suzannehale
  • Photo by Signe Danler
  • Photo by Signe Danler
  • Photo by Signe Danler
  • Photo by Signe Danler
  • Photo by Signe Danler

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

Megachile Bees from Portland-Area Gardens

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Every June – August, from 2017-2019, we collected bees from 25 Portland area gardens. As I start to build out a Bee Guide for Portland Gardens, I wanted to highlight some of the notable bees that we collected. We are still waiting for our 2019 bees to be identified. The details, below, are for bees that were collected in 2017 and 2018 and identified by Sarah Kornbluth (2017) or Gabe Foote (2018).

We collected five species of bee in the genus Megachile:

  • Megachile rotundata (2 females and 1 male)
  • Megachile angelarum (8 females and 5 males)
  • Megachile perihirta (1 female)
  • Megachile fidelis (3 females)
  • Megachile centuncularis (1 female)

Worldwide, Megachile bees are extremely diverse: an estimated 1,400 species of Megachile bees can be found, globally and an estimated 140 species of Megachile can be found in the United States. These bees are in the Family Megachilidae, which includes the leafcutting (e.g. Megachile species), mason (e.g .Osmia species), and wool carder bees (e.g. Anthidium species). In the family Megachilidae, females carry pollen on their abdomen.

In this post, I wanted to cover Megachile fidelis, Megachile perihirta, and Megachile angelarum.

Bee Species Origin Diet Sociality Nesting
Megachile angelarum Native Generalist (Prefers Lavandula, Perovskia, Vitex) Solitary Cavity
Megachile perihirta Native Generalist Solitary Soil
Megachile fidelis Native Generalist (Prefers Asters) Solitary Cavity

Megachile angelarum was the most common bee in this genus that we collected from Portland area gardens.

Megachile angelarum female.

Diet: Although this species has been collected from a broad array of floral hosts (see list from Discover Life), Frankie et al. (2014) note that this species prefers lavenders (Lavendula), Russian sage (Perovskia), and chaste tree (Vitex).

Sociality: This species is solitary, which means that each individual female builds her own nest, collects nectar and pollen to provision her young, and lays her own eggs. In bees with advanced social structures, such as honey bees, the workers collect nectar and pollen to feed the young, and the queen lays the eggs. Solitary bees die soon after they build their nest, load nest cells with pollen and nectar, lay their eggs, and seal the nest cell shut. Many solitary bees may nest in close proximity to each other. Thus, solitary bee doesn’t mean loner bee; it means that the female does all of the work on her own, without cooperation or collaboration from other bees in her species.

Nesting: Megachile angelarum nests in cavities. Rather than cutting leaves, females collect resins and gums to partition nest cells. Since this bee does not cut leaves, it lacks teeth on its mandibles, unlike other bees in the genus. The bee has been found in drilled pine wood (10cm deep holes, 0.5 cm in diameter; Dicks et al. 2010). Other studies have found this species in nest blocks with a 3/16th hole size (Galasetti 2017).

Appearance: Like many bees in this genus, it is a robust-sized bee, with females typically spanning 10-11 mm in length and males a bit smaller, at 8-9 mm in length. The lack of teeth and cutting edges on the mandibles can be helpful for identification.

Megachile angelarum. The mandibles are a bit hard to see, by they are in the lower portion of the face. Note that there are no teeth, or serrated edges on the mandibles, which is a characteristic of this bee.

Notes: Across 2017-2018, we collected this bee from seven different Portland area gardens, or nearly 1/3 of our sampled gardens. Megachile angelarum is likely parasitized by another bee, Stelis laticincta. Stelis laticincta is a social parasite, or cleptoparasite of other bees. What this means is that Stelis laticincta invades the nest of another bee, and lay their own eggs, just as cuckoo birds do with other birds. Once the Stelis laticincta eggs hatch, the larvae kill the Megachile angelarum larvae, and eat the pollen and nectar provisions that have been provided by the Megachile angelarum mother.

We collected a single Stelis laticincta in 2017-2018, and it came from a garden where we collected four Megachile angelarum specimens. Having a healthy Megachile angelarum population increases your chances of having more bee species, by supporting cleptoparasites, such as Stelis laticincta.

Megachile perihirta is commonly known as the Western leafcutter bee.

Diet: This bee is a generalist, and will collect nectar and pollen from many different types of flowering plants.

Sociality: Solitary (see notes for M. angelarum).

Nesting: Unlike many Megachile bees, this species does not nest in cavities, but instead digs shallow nests in the soil (Frankie et al. 2014, page 102). I had thought that all bees in the genus Megachile were cavity nesters. (Actually, I thought that all bees in the family Megachilidae were cavity nesters). But, Eickworth et al. (1981) report that soil excavation was widespread in the family Megachilidae and in the genus Megachile.

Appearance: This was the largest Megachile species we collected. Females  typically spanning 13-14 mm in length and males span 12-13 mm in length.

Megachile perihirta female.

I am soooooo sad that we didn’t collect a male of this species! The males have enlarged forelegs, covered with hairs (photos of the males can be found here and here), which the MALES USE TO COVER THE FEMALES EYES DURING MATING!!!! Biologists suggest that this helps to keep females calm and receptive, during mating (Frankie et al. 2014, page 103).

Notes:  We only collected a single specimen of this bee. It came from our smallest garden (1,800 square feet in size), in an industrial area of Northeast Portland. And seriously: how cool is it to have a bee species where the mating ritual includes the male covering the females eyes with his super-hairy forearms!!!??

Megachile fidelis

Diet: Frankie et al. (2014) note that this species seems to prefer plants in the Asteraceae, including Aster, Erigeron, Rudbekia, Cosmos, and Helenium). Hurd et al. (1980) note that this species is commonly collected from sunflowers (Helianthus).

Sociality: Solitary (see notes for M. angelarum).

Nesting: This is a cavity nesting bee that tends to occupy larger holes (0.65 to 0.80 cm in diameter (Barthell et al. 1998). Unlike Megachile angelarum, which does not cut leaves or petals to line their nest cells, UC Davis has a great photo of a female Megachile fidelis carrying a piece of Clarkia petal. In his native bee research, Aaron Anderson would regularly find bees cutting neat discs from Clarkia flowers. I wonder, now, if collecting petal discs from Clarkia flowers is characteristic of M. fidelis.

Appearance: This species is another robust-sized bee. Females  typically spanning 11-13 mm in length and males span 10-12 mm in length.

Megachile fidelis female.

Once again, I am beyond bummed that we didn’t collect a male of this species! Males of this species also have enlarged forelegs covered with long hairs, although not as pronounced as in male M. perihirta. Once again, biologists suspect that the males use their hairy forearms to cover the females eyes during mating (Frankie et al. 2014, page 103).

Notes: We collected one specimen from a 0.2 acre, flower-filled garden that is adjacent to a golf course in Canby. The other two specimens were collected from a 0.1 acre, flower-filled garden in Northeast Portland. 

Pollinator of the week: Bombus fervidus

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This entry is from Angelee Calder, and undergraduate Agricultural Science student at Oregon State University. It highlights a bumblebee that can be found in Oregon gardens, but that is currently listed as ‘Vulnerable’ to endangered species status, due to documented population declines (Hatfield et al. 2015).

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Dorsal view, Bombus fervidus. This bumblebee was collected from a Portland area garden in August 2018. Photo Credit: Angelee Calder and Isabella Messer

Anterior view, Bombus fervidus. This bumblebee was collected from a Portland area garden in August 2018. Photo Credit: Angelee Calder and Isabella Messer

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When we think of bees, we usually conjure up the image of a cute fuzzy black and yellow puff of an insect. Bombus fervidus, which is also known as the Golden Northern Bumble Bee, looks just like that cute bee stereotype. This bumble bee has a black face, yellow body, and single black band across its body near its wings (Discover Life 2019). Although Bombus fervidus can be found across most of the whole United States, studies have shown that their population numbers are declining (Colla and Packer 2008). This bee is attracted to clover, which is one reason to tolerate (or even embrace) clovers in residential lawns.

We spent 120 hours hand collecting bees from 24 Portland area gardens in 2017 and 2018. In addition, across these two years we set out water pan traps to collect bees for an additional 3,450 hours of passive collection. In all this time, we only collected two Bombus fervidus. Both were collected from the same yard in August 2018. This yard is our largest garden, and it sits adjacent to Forest Park. It could be that this species, known to be in decline, does best with larger patches of habitat, that are close to a natural area.

The Northern Golden Bumble Bee is in the running for cutest bee, so make sure to take a look while he is out foraging. The peak viewing times to catch a glimpse of these cuties May to October (BugGuide.Net 2019).

References

Colla and Packer. 2008. Evidence for decline in eastern North American bumblebees (Hymenoptera: Apidae), with a special focus on Bombus affinis Cresson. Biodiversity and Conservation 17: 1379. https://doi.org/10.1007/s10531-008-9340-5.

BugGuide.Net. 2019 “Species Bombus fervidus – Golden Northern Bumble Bee”, https://bugguide.net/node/view/23135. Accessed February 27, 2019.

Discover Life. 2019. “Bombus fervidus“, https://www.discoverlife.org/mp/20q. Accessed February 27, 2019.

Hatfield, R., Jepsen, S., Thorp, R., Richardson, L., Colla, S. & Foltz Jordan, S.2015. Bombus fervidus. The IUCN Red List of Threatened Species 2015: e.T21215132A21215225.http://dx.doi.org/10.2305/IUCN.UK.2015-4.RLTS.T21215132A21215225.en. Accessed  February 27, 2019.

Pollinator of the Week: Woodland Skipper

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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

Pollinator of the Week: California Tortoiseshell Butterfly

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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

Pollinator of the Week: Virescent Green Metallic Bee

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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.

Pollinator of the Week: Western Tiger Swallowtail

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

A common feature of the urban and suburban landscape, a street lined with large London plane trees (Platanus x acerifolia), complete with lumpy trunks and exfoliating bark, can be a delight to behold. The tree was the favorite species of New York City planner Robert Moses, and became one popular choice for replacing elms affected by the infamous Dutch elm disease during the previous century (1). Chosen for its long life span, interesting growth habit, and ability to withstand the challenges of street life, the London plane has become a ubiquitous member of our cultivated environment. By happy accident, the tree also plays host to the larvae of the familiar and striking western tiger swallowtail (Papilio rutulus) (3).

This large yellow and black butterfly is found throughout the western continental United States and into southern British Columbia. Swallowtails tend to be specialists (2), so the addition of known host trees like the London plane and other members of the Platanus genus, along with willows (Salix spp.), poplars (Populus spp.), and alders (Alnus spp.) is of benefit not only to our parks, streets, and yards, but to these incredible pollinators as well (3). Adult females lay single eggs on the undersides of the leaves of host trees, which then provide food for the developing larvae (4). These larvae eventually form chrysalids and overwinter, emerging the following season as, well, beautiful butterflies (4). While the larvae of the western tiger swallowtail have somewhat specific tastes, the adult butterflies will feast on nectar from many flowering species. These pollinators typically take flight from June through July, but in Pacific coastal areas may be found throughout much of the year (3). They are noted as preferring wetter areas generally, and even as being avid visitors to mud-puddles (5).

Butterflies are of course important to us as gardeners because of the pollination services they provide, but throughout their lifespan they also play an important role as food for other organisms. Douglas Tallamy, from the University of Delaware, writes “if we were forced to care for only one group of insects in our restored suburban ecosystem, we would do well to choose the Lepidoptera” (the order consisting of moths and butterflies) (2). Fortunately for the western tiger swallowtail, and for those of us who enjoy its beauty, our cultivated landscapes should provide ample habitat. With that being said, global declines in flying insects are being documented (see: Insects are In Serious Trouble), and our attention needs to remain fixed as much on what we are planting as on how we are managing these landscapes.

Personally, I wasn’t fortunate enough to see many species of Lepidoptera this past season. I did manage to catch sight of a western tiger swallowtail early in the year, however, at the North Willamette Research and Extension Center foraging on a patch of showy milkweed (pictured above) neighboring the native plants study plot. Being a recent transplant from east of the Rockies, this was my first time ever seeing the butterfly and I was truly blown away. I’m hopeful that despite the challenges faced by these and other pollinators, we will all be able to enjoy them well into the future.

Sources:

  1. Jonnes, Jill. Urban Forests: A Natural History of Trees in the American Cityscape. Penguin, 2017.
  2. Tallamy, Douglas W. Bringing Nature Home: How Native Plants Sustain Wildlife in Our Gardens. Timber Press, 2007.
  3. Haggard, Peter, and Judy Haggard. Insects of the Pacific Northwest. Timber Press, 2006.
  4. “Western Tiger Swallowtail.” Butterflies and Moths of North America, 21 June 2016, www.butterfliesandmoths.org/species/Papilio-rutulus.
  5. Layberry, Ross, et al. “Western Tiger Swallowtail.” Butterflies of Canada, Canadian Biodiversity Information Facility, 9 July 2014, www.cbif.gc.ca/eng/species-bank/butterflies-of-canada/western-tiger-swallowtail/?id=1370403265809.

Pollinator of the Week: Gray Hairstreak

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This post was written by Isabella Messer, an undergraduate working in the Garden Ecology Lab.

The Gray Hairstreak (Strymon melinus(Hübner, 1818)) is a common butterfly in the US. Its habitat spans most of the country with the exception of some states in the midwest (1). The Gray Hairstreak is most common in the southeast but can also be found along the west coast, including Oregon and possibly some of your gardens (1). These butterflies can be identified by their ash-gray color of their wings, their noticeable white-bordered black median line, and a two orange patches on the outer angle of their hindwing (2). Due to their coloring, Gray Hairstreaks can be mistaken for an Eastern Tailed-Blue butterfly which also have orange spots on their hindwing s(3). However, the Eastern Tailed-Blue does not live in Oregon (4). If you want to attract more Gray Hairstreaks to your garden, it would be beneficial to plant  goldenrod, mint, milkweed and winter cress (5). Keep an eye out on a sunny day for these sweet little beauties!

Gray Hairstreak in a Portland garden, August 2017

References

  1. “Species Strymon Melinus – Gray Hairstreak – Hodges#4336.” Species Strymon Melinus – Gray Hairstreak – Hodges#4336 – BugGuide.Net, Metalmark Web & Data, 2017, bugguide.net/node/view/579.
  2. Rodriguez, Lauren. “Gray Hairstreak – Strymon Melinus – Details.” Encyclopedia of Life, Encyclopedia of Life, 27 Apr. 2013, eol.org/pages/262409/details.
  3. Cook, Will. “Gray Hairstreak (Strymon Melinus).” Gray Hairstreak (Strymon Melinus), Carolina Nature, 7 Nov. 2015, www.carolinanature.com/butterflies/grayhairstreak.html.
  4. “Eastern Tailed-Blue Cupido Comyntas (Godart, [1824]).” Butterflies and Moths of North America, Metalmark Web & Data, 18 Aug. 2017, www.butterfliesandmoths.org/species/Cupido-comyntas.
  5. Bartlet, Troy. “Species Strymon Melinus – Gray Hairstreak – Hodges#4336.” Bug Guide, Iowa State University Department of Entomology, 18 Apr. 2017, bugguide.net/node/view/579.

Pollinator of the Week: Yellow-Faced Bumble Bee

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Bombus vosnesenskii foraging on blanket flower in a Portland garden, July 2017.

This entry is from Isabella Messer an undergraduate horticulture major at Oregon State University.  It highlights one of the most common pollinators that we see in Portland area gardens.

Out of the twenty four different garden sites we visit, each month in Portland, we can count on one bumble bee being present in almost all of the gardens. This ubiquitous bee is Bombus vosnesenskii, otherwise known as the yellow faced bumble bee. With increasing evidence that some bumble bee populations are declining, Bombus vosnesenskii populations remains stable (1).

B. vosnesenskii is a very common bumble bee of increasing abundance across the western United States, although it ceases to be very common east of the Sierra Cascade Crest in California(2). B. vosnesenskii is most easily identified by the yellow hairs on the top of the head, on its face, on top of its thorax (middle body part), and as a yellow band at the base of their abdomen (bottom and biggest body part) (2). In terms of the flowers and plants that B. vosnesenskii likes to visit, they are broad generalists (3). This means that they like to visit a broad variety of plants. They are considered ‘medium tongue’ bees, which means that they can drink nectar from a wide array of flowers, with floral morphologies ranging from zinnias, to coneflowers to rhododendrons. Keep an eye out for their yellow heads the next time you are out in the garden and it is very likely you will come across one.

References:

  1. Lozier, Jeffrey D., James P. Strange, Isaac J. Stewart, and Sydney A. Cameron. (2011). Patterns of range-wide genetic variation in six North American bumble bee (Apidae: Bombus) species. Molecular Ecology, volume 20(23), pp 4870-4888.
  2. Koch, Jonathan, James Strange, and Paul Williams. Bumble Bees of the Western United States. US Forest Service and the Pollinator Partnership. PDF.
  3. Tepedino, V.J., Laura C. Arneson, and Susan L. Durham. (2016). Pollen removal and deposition by pollen-and nectar collecting specialist and generalist bee visitors to iliamna bakeri(malvaceae). Journal of Pollination Ecology, volume 19(15). Pp 50-56.

Bombus vosnesenskii foraging on zinnia, in a Portland area garden, August 2017.