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.

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.

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.
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.