Wednesday, July 18, 2018

Pollinators and Wildflowers of Mount McLoughlin

Mount McLoughlin is one of the most stunning and recognizable natural landmarks in the Rogue Valley. With an elevation of 9,493ft it is the sixth highest mountain in Oregon. It is a volcano, and the entire mountain is littered with volcanic rocks. The mountain is located between Medford and Klamath Falls in the Sky Lakes Wilderness. But all that aside, I have looked on at Mount McLoughlin with wonder. I wondered, what is up there? What is it like to be on that mountain? I'm not an experienced hiker, but I had to do this.
Dicentra formosa (Fumariaceae) in the subalpine zone in June
I made four separate treks on the mountain, but only made it to the summit on the most recent hike. My first climb was August 2017. My decision to experience the mountain was a spur of the moment choice. I started on the trail later than was needed to make the summit and descend before darkness fell, so I descended before summiting. My second attempt was in November 2017, one day after another hike which I had achieved a minor injury. The cold and my injury were too much, so I gave up early on the trail.
A view from the ridge, high winds and clouds enveloped the top of the mountain.
June this year I was back on the mountain. Little was in bloom, and it was fairly cold. I had arduously reached the ridge, but dark clouds were moving in around the mountain from the East. Thunder was rumbling from the distance. Before I knew what was happening, the storm was right overhead. Snow and lightening prompted me to make a swift descent! In my slightly panicked haste, I lost the trail several times on the way down through the subalpine zone (dominated by many large basalt fragments, dwarf trees, and a poorly discernable trail). It was not ideal.
Wasp-mimic syrphid fly (Chrysotoxum) eating pollen on Lilium pardalinum
I encountered much more pleasant weather on the mountain this July. Driving up to the trailhead on a pitted rocky dirt road, I passed by so many wildflowers in bloom! It was exactly what I needed to boost my spirits and give me the optimism I needed to reach the summit, finally.
Pacific coralroot orchid (Corallorhiza mertensiana; Orchidaceae)
Gleefully on my way up the trail, eyes mostly to the ground, I spotted a delightfully intriguing plant! Of course I encountered many interesting plants, but one that stood out among the rest was the parasitic coralroot. Instead of photosynthesizing, these orchids get all they need from relationships with ectomycorrhizal fungi. The fungi gets what it needs to live from relationships with the roots of surrounding conifers.
Pompilid wasps
As I progressed up the trail, I noticed the characteristic wing flicking of spider wasps (Pompilidae). Four or five small pompilids were very interested in a small area on the side of the trail, maybe a few inches in diameter. Most pompilids hunt spiders to paralyze and feed to their young, but some are kleptoparasites of other pompilids. I found one such kleptoparasitic pompilid last year. I can't help but wonder if these too were kleptoparasites attracted to the hidden burrow of another pompilid.
Scree on the southern face of Mount McLoughlin
Finally, and arduously, I reached the subalpine zone. The trees are sparsely distributed, dwarfed, and contorted. Soil, if you could call it that, is highly mineral, mostly sand and fine gravel. Wildflowers were blooming everywhere in pockets between large rocks. Deep roots keep the plants anchored in the loose dry substrate. Hiking at this stage becomes challenging, and the trail is frought with many obstacles. This is when the fun begins.
Eriogonum pyrolifolium (Polygonaceae)
Life high on the mountain is hard for plants. Prolonged snow cover, harsh weather, strong wind, loose soils, a short growing season, and animal predation creates a very trying environment for high elevation plants. Most of these plants cope by having deep extensive root systems and small above ground manifestations. Many bloom very quickly as soon as weather permits to cope with the short growing season. Summer for us in the lowlands is spring on the mountain.
Pinus contorta in the subalpine zone
The trail becomes slightly harder to follow as one gets higher on the mountain. It's not that there isn't a discernable trail, but that there are many discernable trails, likely from hikers that came before you that went the wrong way. My view is that it is hard to get lost going up. All you have to do is just go up. Going off the beaten path might make the ascent more difficult, as was my case. This was partly due to my desire to A.) see more wildflowers, B.) explore my own limitations, and C.) avoid other hikers.
Bombus mixtus on Eriogonum marifolium ♀
During my hike, the most numerous wildflowers were a few species of Eriogonum, or wild buckwheats, namely E. marifolium and E. pyrolifolium. The yellow flowered E. marifolium is interesting in that it is dioecious, that is, plants are either male or female. Female phenotypes have flowers which turn red as they age, while male phenotypes have all yellow flowers with a shorter corolla. In my observations, eriogonums are visited by a wide range of pollinators.
Large pompilid wasp on Eriogonum marifolium ♂
While there were bees present on many of the mountain wildflowers, the most conspicuous floral visitors were spider wasps. Large and small pompilids were on nearly every eriogonum I encountered. In other words, sit and watch an eriogonum and within a minute there would be at least one, sometimes two, pompilids on the flowers.
Pompilid wasp visiting Eriogonum pyrolifolium
Spider wasps are some of my favorite wasps. Not only do I think their way of life is brutal and cold (AKA very cool!) but they have a beautiful form. While they are rarely brightly colored, they do attract attention by their rhythmic wing flicks and jolty movements. Some species are known to have painful stings, something I would like to explore in greater detail.
Eriogonum pyrolifolium
Eriogonum pyrolifolium has an odd common name: dirty socks. The internet claims it is a tip of the hat to their delightful smell. I haven't thought to give them a whiff. Yet. Maybe the next time I see these flowers I will remember to smell them.
Bombus vandykei queen and worker on Penstemon davidsonii
Davidson's penstemon is found in varying elevations on the mountain, normally in rock crevices. It is probably exclusively visited by bees. I have not seen any pollinator but various bees visit it on my various hikes up the mountain.
Bombus on Castilleja arachnoidea (Orobanchaceae)
Paintbrush are strange plants. They are thought to be parasitic on the roots of other plants growing nearby. Flowers are hidden within bracts that must be folded back by bees to access the nectar. Osmiine bees and bumble bees were foraging on them during my hike, and interestingly enough, it was the first time I've seen any pollinator visiting Castilleja.
Ammophila nest entrance, covered by a single pebble.
Thread waisted wasps (Ammophila; Sphecidae) are pretty awesome, and plentiful on Mount McLoughlin. They are fairly nervous creatures. Their nests, which are provisioned with paralyzed caterpillars, are constructed in sandy soils. They have the peculiar behavior of using a pebble to cover the entrance while they are looking for prey. When the nest is provisioned and eggs are laid, the entrance is covered completely by sand and debris to hide any sign of a nest to discourage parasites.
Ammophila female above her nest entrance
By a stroke of luck, I happened to be sitting and drinking some water on the scree when a thread waisted wasp alighted right next to me. She removed the pebble covering the entrance to her nest (which I hadn't noticed previously) and proceeded to continue excavation.

When thread waisted wasps are excavating their nest tunnels, the excavated sand is deposited away from the entrance of the nest so as not to draw attention to the location of the nest entrance.
Luetkea pectinata (Rosaceae)
Partridgefoot (Luetkea pectinata) is a plant that seems to grow exclusively on the south facing scree. I haven't ventured onto the northern or western slopes to determine if it grows there, too. Flies sem to have been the primary pollinators, though bumble bees were also seen on the flowers.
A view down the northeastern flank
Did I mention it was hot? It was hot. I was staying hydrated, but a pounding headache was making the already difficult trek even more difficult. I started to feel like Frodo on Mount Doom trying to deliver the One Ring to the firey pit from whence it came. At this point my entire body was jelly and I was questioning my life choices.
Hulsea nana (Asteraceae)
While eriogonums still managed to hold some ground in the alpine zone (there are no trees here), Hulsea nana was the champion of the harsh conditions of the top. The exquisite foliage alone make this plant a treat, and the bright yellow daisies were encouraging. Small flies were visiting the flowers, but I had lost the will to wait for a good photo opportunity. Onwards and upwards, keep going up! (I kept joking to myself that there were just a few vertical miles to go.)
Eriogonum pyrolifolium near the summit with... a honey bee?!
Yeah. I get within ten minutes of the summit and I see a honey bee. Why did I not see a single honey bee anywhere else on the mountain? Where did she come from?! I wonder if she was from a managed hive somewhere at the base of the mountain, or a feral colony hidden within a rock crevice or tree hollow. The mystery will haunt me until I die.
A tiny wasp lands on me once I reached the summit, Platygastridae?
I have long since unlearned the habit of immediately brushing off an insect that finds its way onto my skin. First, I look to see what it is. In this case, it was a tiny wasp! The quality of the photo is probably too poor to ever get a positive ID, but knowing that wasps are equally attracted to me as I am to them makes my heart happy.
Horntail (Urocerus; Siricidae) on the Mount McLoughlin summit
So, I made it to the summit. It was epic! There were exactly zero plants growing on the tip top, but there must have been thousands upon thousands of insects; mostly flies and horntails. Woodwasps, sawflies, and horntails are ancient phytophagous (plant feeding) progenitors of wasps. Siricid woodwasp larvae feed on decaying wood of conifers.
A view of fellow hikers on the summit, looking southeast

Friday, June 22, 2018

More Bees from Spring '18

Here we are halfway through June. How is it already summer? It seems like just a few weeks ago the pears were blooming and I was working in rain and cold trying desperately to get the spring work done with the honey bee hives. Now it feels like summer is in full effect, rain is less and less in the forecast, and multitudes of bees are busily seeking mates and provisioning nests!
Cuckoo bee (Nomada, Apidae) on arrowleaf buckwheat (Eriogonum compositum, Polygonaceae) in the wilds
The most familiar and recognized bees are honey bees, poster child of pollinator conservation alongside monarch butterflies. But the overwhelming majority of native bees in the US and the world are solitary and nearly half of those collect pollen from only one family of flowering plants. Of course, the plant family varies between different bees. Many of the most common bees are generalists who visit a wide range of flowers from many families. In either case, a diverse range of flower types from a range of families is the best for facilitating a diversity of bees.
Male carpenter bee (Xylocopa tabaniformis, Apidae) on comfrey (Symphytum officinale, Boraginaceae) in my garden
Large carpenter bees, Xylocopa spp., are very conspicuous in my garden. My yard is fenced with ratty looking cedar boards serving as habitat for countless Xylocopa nests. The boards are only about 3/4" thick, but the large bees somehow create vertical nests within the boards without breaching the surface. I think this is incredible, and I have no idea how they can detect the outside edge of the wood.
Carpenter bee on a foxglove (Digitalis purpurea, Plantaginaceae) in my garden
Foxgloves, native to this part of Oregon, grow in my garden. Carpenter bees have no idea how to get in, so instead they just bite holes at the top. Even then, they are not very attractive to most of the bees in my garden.
Male carpenter bee on wood spurge (Euphorbia amygdaloides, Euphorbiaceae) in my garden
Wood spurge, Euphorbia amygdaloides, was surprisingly attractive to some pollinators in my garden. Carpenter bees, beetles, flies, and even paper wasps were attractive to the odd musky smelling flowers. Unlike most flowers visited by bees, euphorbia flowers don't produce nectar. For the species that do produce nectar, it is secreted from bracts below the actual flowers, sometimes appearing like petals or sepals which are absent from all euphorbias.
Xylocopa, a mosaic gynandromorph, perched on a Salvia (Lamiaceae) in my garden
Speaking of bizarre, did you know that some hymenopterans have both male and female characteristics? This is called gynandromorphism. Sexual dimorphism, present in the Hymenoptera, is where sexes of the same species exhibit differing characteristics beyond their genitalia (i.e. scopae, not found on male bees). I stumbled upon one or possibly two Xylocopa gynandromorphs in my garden.
Xylocopa, a mosaic gynandromorph, perched on a Salvia (Lamiaceae) in my garden
I took photos of the carpenter bee, found in the morning before it had warmed up enough to fly, and hadn't realized it might be a gynandromorph until looking at the photos later. It was a mosaic gynandromorph, only having patches of male characteristics rather than being a bilateral gynandromorph (literally half male and half female). Web searches revealed that gynandromorphism isn't unheard of in Xylocopa, but maybe not all that common either.
Xylocopa gynandromorph under magnification (microscope courtesy Old Sol Bees). Male (L) and female (R)
After sharing the images of my Xylocopa gynandromorph on social media, I felt regretful for not having captured the insect. Returning home, I immediately went to my garden, net in hand, and watched as the carpenter bees foraged for resources and males chasing each other off. I captured and released a few males and one large female. I was about to give up when I saw a peculiar individual. I netted it exiting a nest tunnel, and sure enough it was a mosaic gynandromorph. It was an intermediate size between a typical male and female, and had scopae on both legs. It appeared to be provisioning a nest, so perhaps it was also fertile. Gynandromorphs are generally considered to be infertile. The specimen has been vouchered, and I am interested in donating it to a museum.
Halictus (Halictidae) visiting a foxglove, correctly, in my garden
As mentioned previously, few bees visited the foxgloves in my garden. The only bees I observed visiting the flowers properly (sans nectar thievery) were small carpenter bees (Ceratina) and sweat bees (Halictus). The most numerous visitors to the foxgloves were ants. They were probably attracted to the nectar, but ant pollination in this case seems unlikely because of how the reproductive structures are positioned within the flowers.
Halictus on a buttercup (Ranunculus sp., Ranunculaceae) in the wilds
Halictus is one of the most common genera that I observe. They visit a wide range of flower types, but mostly open flowers with either easily accessible pollen or nectar. Many can be easily identified by the small notch seen at the tip of the abdomen. Buttercup pollen is toxic to some bees, or at least to their offspring, though it seems to have no effect on some bees.
Small bees foraging on deerbrush (Ceanothus integerrimus, Rhamnaceae) in the wilds
Deerbrush (Ceanothus integerrimus) and the earlier blooming buckbrush (C. cuneatus) are both very attractive plants to many pollinators as well as this human. They are shrubs, and when in bloom are covered in panicles of tiny simple flowers. Most of the pollinators are also very small, typically bees and beetles. They are graceful and rewarding plants which also fix nitrogen into the soil with specialized root nodes formed by a bacterial partner.
Halictus ligatus on a yellow yarrow (Achillea sp., Asteraceae) at the Jackson County OSU Extension in Central Point, OR
When I first started researching what to plant for bees years ago, yarrow was one of the first plants I tried to grow. It was fairly easy from seed, and took practically no water once established. Yet, over the years I observed few pollinators visiting the flowers. Ladybugs are probably the most frequent visitors that I can recall. This yellow variety seemed to garner the attention of a variety of small sweat bees (Halictidae) and small carpenter bees (Ceratina) at the OSU Extension in Jackson County.
Halictus ligatus foraging on narrow leaf mule ears (Wyethia angustifolia, Asteraceae) in the wilds
A larger and more popular relative of yarrow, narrow leaf mule ears are very popular with bees where they bloom in forest clearings around the Rogue River area. Many types of bees visit Wyethia, including bees from the families Apidae (including honey bees), Halictidae, and Megachilidae.
Osmiine bee (Megachilidae) visiting narrow leaf mule ears
I attempted W. angustifolia from wild-collected seed. I managed to get the seeds to germinate with cold stratification (a fancy way to say I left the pot outside through winter), but killed most off after that. There were a few small individuals which I successfully managed to not kill into their third year, but they died promptly after transplanting into my garden. Perhaps they are not currently in cultivation due to tragically fragile root systems, or I just need to do a better job next time.
A honey bee foraging on carrotleaf horkelia (Horkelia daucifolia, Rosaceae) in the wilds
One of my favorite plants, perhaps only due to obscurity, is an uncommon rose relative native only to Southern Oregon and Northern California. The plant is somewhat uncommon, so when I happen upon it I feel fortunate and grateful. Pollinators of all types visit it for nectar and pollen, the open flowers don't care who is pollinating it. Many types of bees, flies, beetles, and butterflies are always attracted to it in my observations, weather permitting. Where situated near an apiary, it attracts honey bees.
Honey bees love trailing snowberry (Symphoricarpos hesperius, Caprifoliaceae) in the wilds
Snowberry, like carrotleaf horkelia, is very unassuming. Creeping or trailing snowberry likes growing in somewhat shady locations under a canopy of conifers or in clearings. The flowers, small and easy to miss, are typically hidden under the foliage. Honey bees don't have any trouble finding the flowers. Snowberry honey is highly sought after, apparently, though the author has never tried it. I have only ever seen honey bees visit these flowers, though I would bet they are also popular among bumble bees since not many bees forage in shady locations besides bumble bees.
European woolcarder bee (Anthidium manicatum, Megachilidae) forages on lamb's ear (Stachys byzantina, Lamiaceae) in my garden
Back in the garden, lambs ear is in bloom with fuzzy flower spikes interspersed with small purple flowers. European woolcarder bees, an introduced species, have a special relationship with this plant and seem to be attracted to it wherever it is grown. Females forage almost exclusively on the lambs ear, while males fiercely defend the area from other males and most other bees by chasing or grappling.
European woolcarder bee (Anthidium manicatum, Megachilidae) forages on lamb's ear (Stachys byzantina, Lamiaceae) in my garden
Woolcarder bees, introduced or native, are in the Megachilidae. All megachilid females collect pollen on scopae under their abdomens rather than their legs like most other bees. Woolcarder bee females also collect hairs from plants such as lambs ear to line and partition cells in small tunnels and other small cavities.
Small carpenter bee (Ceratina, Apidae) on a Penstemon in the Jackson County OSU Extension in Central Point, OR
Small carpenter bees, very unlike their larger relatives, nest in dried pithy stems of plants like roses or many woody perennials. These bees are very small, easily mistaken for small flies, but are also very common. Here I witnessed one perched on a penstemon flower to groom itself. The penstemon flowers are deep and narrow inside, perfect for small bees to climb right in to reach the nectar and in doing so brushing against the reproductive organs.
Cuckoo bee (Nomada, Apidae) on arrowleaf buckwheat (Eriogonum compositum, Polygonaceae) in the wilds
Growing in hot dry rocky locations by the Rogue River, arrowleaf buckwheat attracts a range of tiny flies, beetles, butterflies, wasps, and bees. One peculiar bee, one of my favorites, was visiting the eriogonum during one of my photo sessions. This is a nomad cuckoo bee related not too closely to honey bees and carpenter bees. The cuckoos are kleptoparasites, nest thieves, of other ground nesting bees.
Cuckoo bee (Nomada, Apidae) on arrowleaf buckwheat (Eriogonum compositum, Polygonaceae) in the wilds
As nest thieves, cuckoos require neither to collect pollen nor to build a nest. Needless to say, they don't possess specialized pollen collecting hairs, so they often appear very wasplike. Females fly low to the ground in a zigzag pattern trying to detect the scent of a host nest. Once a nest is located, she will enter and deposit one of her eggs in a finished or nearly finished cell, sealing it behind her. The cuckoo larvae either kills or starves the host larvae, and develops on the host provisions.
Masked bee (Hylaeus, Colletidae) on arrowleaf buckwheat (Eriogonum compositum, Polygonaceae) in the wilds
Yellow faced bees, or masked bees, are also wasplike due to lacking pollen collecting hairs. Instead of collecting pollen on scopae or corbiculae like other pollen collecting bees, they eat it. The pollen in regurgitated from their crop when they return to the nest, and formed into a ball within each cell.
Masked bee (Hylaeus, Colletidae) on arrowleaf buckwheat (Eriogonum compositum, Polygonaceae) in the wilds
Because cuckoo bees and masked bees do not have much hair on their bodies, they are not thought to be very effective pollinators. However, some pollen adheres via a static charge or with microscopic velcro-like projections. Flying insects, especially bees, develop a positive charge from flight while grounded objects like plants carry a negative charge. This helps the pollen become unstuck from the anther and attracted to the insect. The impact of the charge on the pollen is minimal, but every bit counts!
See the "mask" of a male masked bee
Bees, among other fascinating insects (like wasps), are fun to learn about! Observing which flowers they visit and what type of bee is visiting is an ongoing experiment that everyone can take part in. Gardens present an additional dimension of interest. Watching native pollinators visit nonnative garden plants or weeds, or watching nonnative bees visit native plants, is an interesting way to study the theory of pollination syndromes. I imagine someday someone could develop a pollination syndrome chart for specific types of bees based on flower shape, color, characteristics of pollen or nectar, et cetera. Maybe such a chart could aid in conservation efforts geared towards at-risk species of bees or other pollinators. Until then, just go watch some flowers and see what comes of it.

Monday, May 14, 2018

Bees in Spring 2018

Spring is the best time in Southern Oregon to watch bees! The combination of highly diverse wildflower communities, excellent climatic conditions, and a relative abundance of water culminates to produce a great situation for many species of bees. Without looking up the data, I would bet that the highest diversity of bees can be found in the spring months in Southern Oregon. Not only have I seen more different kinds of bees in the spring than in summer or fall, but there are more native plants in bloom in Southern Oregon than later in the year which offer a diverse nutritional palate.
A honey bee clings to a willow catkin with one leg while grooming the pollen into her pollen baskets. February 22nd.
The earliest blooms in Southern Oregon are found on the trees. Alder, hazel, and willow are some of the first trees to bloom and produce an abundance of pollen for the few bees active at this time as well as a plethora of flies and beetles that feed on pollen. When apiaries or the odd feral honey bee colony are located near any of these trees, often near bodies of water, they delight in the abundant pollen on warm sunny days. Few native bees are active in January or February when the earliest blossoms appear, but I saw Andrena and a few bumble bee queens foraging on willow catkins in February this year.
A mating pair of Ceratina on pear blossoms. April.
Southern Oregon in April is host to billions of pear blossoms. Pear orchards are fairly commonplace around Medford, though many have been sold and turned into housing developments or hemp farms, much to the dismay of bees and other pollinators. Pear growers use honey bees to pollinate their trees, but the beekeepers make a fraction of what they are paid per hive in the almond orchards in California. Where almond growers may pay up to $200 per honey bee hive in the almond orchards of the Central Valley in California, pear growers rent less hives and might pay up to $40 per hive. This is probably because almonds bloom much earlier than pears, a time when few native pollinators are active, and almonds are currently much more valuable than pears. Consider the cost of pears compared to the cost of almonds next time you go grocery shopping.
A mating pair of Ceratina on pear blossoms
The pear orchards of Southern Oregon, at least the ones I have been in, are surrounded by a lot of natural landscapes and filled with flowering weeds. Whereas almonds are harvested by shaking the trees and then raked from the ground, the floor of the almond orchards needs to be bare or mowed. Pears are not collected this way, so the ground beneath the trees is sometimes overgrown with weeds. This offers a lot of resources for native and managed bees alike.
Osmia on a crab apple blossom. May.
Apple blossoms follow the pears. I am not sure there are many apple orchards in Southern Oregon, but they are grown as ornamental trees and personal orchards. Mason bees, Osmia spp., are sometimes managed for pollination of spring tree crops including almonds. Unlike honey bees, each female creates her own nest and does not live socially. In fact, most female native bees fulfill the role of both queen and worker. Osmia are called mason bees because they use mud to build the cell walls and partition cells in their nests (preexisting linear tunnels, usually in wood).
Nomada on a crab apple blossom
Peculiar, wasp-like, and fascinating. That is how I like to introduce the cuckoo bees. As the common name implies, they steal the nests of other bees. Unlike the birds of the similar name, cuckoo bees lay an egg in the cell of a host bee, such as Andrena or Halictus, and the cuckoo bee larvae usually kills the host larvae and develops on the food (a ball of pollen) collected by the host bee. Since the cuckoo bees steal nests from other bees, they don't create nests themselves. Since the nest they steal is provisioned by the host, they have no need to collect pollen, and thus they don't have pollen collecting hairs on their bodies.
Nomada female searching for host bee burrows
Cuckoo bees in the genus Nomada are usually black, yellow, red, or a combination of those colors. I was lucky to see a few red and black females hovering just inches from the ground recently. They were seeking host nests, probably Andrena or Halictus which nest in soil. Nomada females find Andrena nests by olfactory cues (Cane 1983).
Anthophora female on Phacelia tanacetifolia. May.
Phacelia tanacetifolia, or lacy phacelia, is a member of the Boraginaceae, native to California and possibly Oregon. It is more commonly available as seed and usually grown as a cover crop, ornamental, or sometimes specifically for bee forage. It doesn't let down, it is a great bee plant. Bees of all shapes and sizes, as well as a variety of other types of pollinators, are attracted to the blue scorpioid inflorescences.
Anthophora female on Phacelia tanacetifolia
I recently had the opportunity to observe bees visiting a large planting of P. tanacetifolia at Easy Valley Farm in Rogue River, OR. One of the more conspicuous types of bees were the large and fast digger bees. Anthophora is a common and widespread genus with some species remaining active from spring to fall. While some solitary bees only have a single generation each year, some species have two or multiple generations. At least some if not most species of Anthophora produce offspring all year, with the last generation of the year overwintering as prepupae within underground nests.
Halictus on Phacelia tanacetifolia
Sweat bees, more accurately known as halictid bees since not all species are attracted to sweat, are very active in spring and summer. They vary widely in size and nesting habits, and are very widespread and speciose.
Bombus vosnesenskii clinging to an Anchusa azurea blossom
An Old World member of the Boraginaceae, Anchusa azurea is found in my garden and in those fortunate enough to have acquired it from seed. It is like a large forget-me-not, and is very attractive to bumble bees and honey bees. I photographed an odd flower with only four lobes, most have five, with a bumble bee clinging to it early one morning. This bumble either was caught in the cold and unable to return home, or wanted an early start.
Iris chrysophylla with a bumble bee
Iris chrysophylla, yellowleaf iris, is a dryland iris found among grasses in mixed coniferous forest clearings and edges. It blooms profusely in mid spring over a long period in Southern Oregon. Various bees visit the flowers, including mason bees, halictid bees, and bumble bees. Though it is visited by various bees, I do not typically see a lot of bees visiting the flowers even where it is blooming in large masses.
Bombus diving for nectar on Iris chrysophylla
Iris flowers, as well as a few other Iridaceae relatives found around the world (i.e. Hermodactylus, Moraea), are complex and peculiar. To oversimplify, each single flower is divided into three ports of access for bees to enter seeking nectar. Pollen is typically deposited onto the back of the bee, but only if it enters the correct way. Bumble bees have very long tongues and are able to circumvent the reproductive structures and access the nectar from the side.
A honey bee forages for nectar on Calochortus tolmiei
While Iris chrysophylla grows from a short rhizome, Calochortus tolmiei grows from a bulb. Calochortus is only found in the New World and is very unlike other New World bulbs in flower structure. C. tolmiei is one of a handful of species with peculiar hairs on the petals, likely an adaptation to prevent inefficient pollinators from stealing the nectar. Nectar is excreted from colored patches at the base of the petals, and the hairs force the bee to rub against the anthers to access it.
Calochortus tolmiei and a honey bee fleeing from a camera that came too close for comfort.