Monday, July 18, 2016

Floral Visitors XXI

Allium ampeloprasum var. ampeloprasum with Strymon melinus & Bombus vandykei
If you have a flower garden, it is probably teeming with life right now as mine is. Bumblebees, honeybees, a variety of small solitary bees, large carpenter bees, wasps, skippers, swallowtails, hairstreaks, beetles, and a variety of other beneficial insects are frenzied over the buffet I have planted for them. This is an ideal situation, one that I strive for. The key to my success attracting such a wide array of pollinating insects is the wide array of floral forms presented. Even just within a single genus of flowering plants there will be variation of pollinator types between species, which has been the case for the gray hairstreak butterflies and elephant garlic. I have not seen the hairstreak on the drumstick allium (Allium sphaerocephalon) which is planted nearby, and similar phenomena occur throughout the year with other plants. That is one of the most interesting aspects of planting for pollinators.

Many people here keep ungulates and ruminants or grow hay for sale as animal fodder, and few if any are likely to be as environmentally conscientious as the readers of this blog. Diverse flower plantings have been demonstrated to increase the amount of beneficial insects (predators, parasitoids, pollinators, etc.) in a farm setting (Altieri & Letourneau 1982Douglas et al. 2000, etc.) and likely in a garden setting as well. The Xerxes Society book Farming with Native Beneficial Insects cites many studies which go further and say that native wildflower plantings attract a higher diversity of beneficial insects while weedy field borders host more pest insects. Additionally, wildflowers may attract more native pollinators which will take some of the pressure off honeybees and simultaneously improve crop yields of crops that require pollination. An initial investment of time and money will pay off in years to come by reducing pest populations and enabling a farmer to reduce or possibly forgo the use of chemical pesticides altogether, which would all increase the profitability of their operation. Why then don't more farms plant flowers?

Allium ampeloprasum var. ampeloprasum with Strymon melinus & Bombus vandykei
Pollinators can be indicative of the area. Gray hairstreaks, occurring across the nation and spanning between Canada and Venezuela, are typically found in nonforested disturbed weedy areas. This is somewhat peculiar since we live basically at the edge of an expansive mixed coniferous forest, though as one goes deeper into the valley or closer to "civilization" there are less trees and more nonnative species, including humans.

Allium ampeloprasum var. ampeloprasum with Apis mellifera
I have mentioned before that alliums are good plants for pollinators. The reason for this is the bloom times between species is incredibly variable, and each bulb flowers over an extended period as new florets continue to open. Elephant garlic (Allium ampeloprasum var. ampeloprasum ) is one of my favorites and is incredibly easy to acquire, though one must procure fresh cloves or else they may never come up. The leaves appear in early spring and look very similar to corn as they clasp the stem, then dry up as the scape elongates up to four feet tall or more. The actual inflorescence itself is close to four inches across and as you can see is composed of hundreds of small lily like florets. Elephant garlic is very closely related to the leek and is only separated taxonomically at the varietal level, with the primary morphological difference being the bulb.

Thread-waisted wasp (Ammophila sp.) on Allium sphaerocephalon
A similarly accessible onion is the drumstick allium, Allium sphaerocephalon. These grow up to three feet, but usually shorter, with flower heads the size of a ping pong ball. They are similarly attractive to a variety of bees as are other alliums. Some find them to be weedy or difficult to remove, but this trait isn't bad for a pollinator garden since the purpose triumphs over the aesthetic, although to me those factors are one in the same. I would suggest planting them in drifts or clumps to enhance the effect, and close to other perennials which will help support the thin yet sturdy scapes.

Ammophila sp. on Allium sphaerocephalon
Large and fast moving thread-waisted wasps (Ammophila sp.) are a good ally in the garden as they parasitize caterpillars and sawfly larvae to feed to their own larvae in underground nests. They are solitary, and much more likely to flee than to be aggressive, although the females can technically sting people (which would probably require one to capture the poor creature and hold it bare handed).

Ceratina sp. on a Hemerocallis hybrid
As far as I'm concerned, daylilies are some of the poorest pollinator plants in my garden. Typically they are either moth or butterfly pollinated (depending on the species) and are only on rare occasions visited by bees. Honeybees? Probably never, but I have heard reports of bumblebees visiting them when planted in masses. I have a few plants, I'll admit, but they were free. I am surprised to find small carpenter bees inside, and on more than one observation. The tiny bees are perhaps able to reach the nectar hidden deep inside, and may even collect some pollen.

Ceratina sp. with pollen on a Hemerocallis hybrid
Unlike the larger carpenter bees (Xylocopa sp.), Ceratina are not large enough to excavate tunnels into wood but rather the dried pith of woody stems from plants like blackberry (Rubus sp.) and the like, though I'm not sure which native plants they prefer to nest in. Females forage for an extended period, pretty much until they can't (mid autumn) and finally rest at the entrance of their linear pithy nest where they die (frosted, I'd imagine), blocking the entrance to potential intruders. The following year the brood pupate and emerge to start the cycle anew.

Selasphorus rufus ♀ on Crocosmia 'Lucifer'
A few other plants in my garden are also marginally good pollinator plants. Irids (aka plants in the Iridaceae, or Iris family) such as Crocosmia and Gladiolus attract few insect pollinators, yet are excellent for the hummingbirds. Crocosmia is a fairly weedy genus, particularly annoying to gardeners in mild coastal climates as the plants can easily escape and become nearly impossible to remove. Crocosmia grow from corms, which unlike true bulbs are technically a part of stem modified for storing starches and nutrients. Corms of these offset freely, and any attempt to remove them must require removal of all the offsets.

Selasphorus rufus 
The Rufous hummingbird is a migratory species which spend spring and summer in my garden, and even as far north as Alaska. In the fall, they migrate as far south as Southern Mexico. They feed primarily on nectar, but are also insect predators, and I suspect bees and other pollinators to be included in their diet. I suspect they nectar on natives such as the locally common Lonicera hispidula as well as Arbutus menziesii which flowered earlier in the year. Crocosmia is one of their favorites in my garden, though I have also seen them visit some of the taller alliums and a few of the plants in the Boragnaceae including Anchusa azurea, not the typical hummingbird plant. They may also be one of the visitors of the Salvia sclarea in my garden, though I haven't directly observed this.

Gladiolus hybrid reproductive structures
For the first time this year, I have observed a hummingbird visiting the tall hybrid Gladiolus growing alongside the Crocosmia. This would be the first time I have ever witnessed any pollinator visiting the Gladiolus. If space is limited and you would like to plant for pollinators, I would suggest adding Gladiolus to the list of plants not to use along with Hemerocallis.

Sedum album with Apis mellifera
Fortunately there are plenty of other plants in the garden for bees to party on, including various sedums. The most floriferous, and prolific, is Sedum album. This is one of the easiest plants to propagate, one could simply tear a stem or few leaves off and toss them wherever there is soil (or sand, or gravel) and they'll form roots and grow. I wonder if I could pin it to a wall and see if it would root. Little to no water is required, and it flowers prolifically regardless.

Sempervivum sp. with Apis mellifera
I suspect flowers in the Crassulaceae such as Hylotelephium, Rhodiola, Sedum, and Sempervivum to be prolific nectar producers under conditions that would be considered harsh for other plants, or produce nectar with a very high sugar content, or both. In my experience these are nearly literal bee magnets, bees of many types being highly active on the blooms. While the flowers of Sedum tend to be small individually, the flowers of Sempervivum are much larger, and quite stunning.

Sempervivum sp. with Bombus vandykei
Sempervivum is a monocarpic genus, which means they do not flower for a long time (perhaps years), then use all of their energy to flower prolifically and then die. Fortunately they usually produce many offsets which live on after the "mother" dies. I am also hoping that this plant and another that are in flower will set seed for me to attempt. The advice I have been given is to surface sow, though there have been conflicting suggestions as to whether they need cold stratification or not.

Magnolia sp. with Apis mellifera
Another prolific nectar producer is the magnolia, typically a beetle pollinated genus. The genus is very ancient and evolved when beetles were the primary pollinators of insect pollinated plants. The flowers likely provided shelter, a place to seek mates, and as a source of food (pollen, primarily). The large waxy petals close up at night, enhancing the flower as a protective shelter. Beetles pollinate the flowers by climbing up the center structure, the base of which is lined with the anthers which are topped by a crown of stigmata (plural of stigma, not crucifixion wounds). Waxy petals at a certain stage, I surmise, may be more difficult for a beetle to climb, and so the beetle would be forced to cross first the anthers and then the stigmata to escape, transferring pollen on the way.

Lathyrus latifolius with Apis mellifera
Outside the garden in weedy sites like roadsides and forgotten pastures there are a number of weeds proliferating in the aftermath of the destruction of the native ecosystem many decades ago when the first settlers arrived to this area and "improved" it. One such weed is the common perennial sweet pea, a vine once planted to reduce erosion around roadside ditches and similar areas. It has few, if any, natural predators, and spreads primarily by seed. The vines have tendrils that wrap around nearby plants, including blackberry, smothering everything below.

Lathyrus latifolius with Apis mellifera
My previous assumptions were that nonnative sweet peas in general were not visited by honeybees, and were only visited by large bumblebees and carpenter bees. This year I have been forced to reassess my assumptions, and from the photos it is clear that honeybees do in fact visit sweet peas. Small Megachile sp. were also seen visiting the flowers. All of the bees access the nectar from the top of the flower, negating the need to move any petals.

Daucus carota with Apis mellifera
Years ago I had attempted to learn if honeybees visited the wild carrot, Daucus carota, that grows rampant in the area. I had been told by many beekeepers that honeybees either never visit the flowers, only visit them once every ten years, and that if they do visit the carrot it ruins the honey. This is the second year in a row I have observed honeybees on the carrot flowers, so the ten year wives tale, suspicious to begin with, goes out the window. Last year's honey from my own hive tastes great, and obviously they visit Daucus, so hereby goes the death of the other two assumptions.

Daucus carota with Apis mellifera
This particular plant, clearly in fact, particularly attractive to honeybees as for a two hour period while I was in this yard (an apiary, in fact) there were at least four honeybees each time I looked. Variation between individual plants doesn't need to be restricted to their appearance, although that is what is most apparent to us. Fitness and general hardiness will vary between individuals, as will the production of certain constituents inside the plant. This is apparent to breeders of plants used for their medicinal properties, such as Echinacea which have varying amounts of phenolic compounds, alkamides and polysaccharides between individuals not to mention species. It is not a great leap to consider nectar production to vary with sugar content or other factors.

Dipsacus fullonum with Bombus vosnesenskii
More common in agricultural sites than elsewhere, common teasel is an abundant biennial European native that is in bloom now. In my observations they were highly attractive to both bumblebees and honeybees, with emphasis on the former. Other observers have reported bumblebees being the most frequent visitors along with some dipterans in a site in Canada, while observations in a site in England reported the majority of floral visitors to be dipterans, primarily Syrphidae, followed by visitation by lepidopterans and bumblebees. (See Gucker et al. 2009). Studies also show that the plants are highly dependent on insect pollination and will not set seed when pollinators are excluded.Considering honeybees, another nonnative species, this may be a case of an invasive mutualism where two nonnative species support each others proliferation in the foreign land. Such a scenario was found to be the case with yellow star-thistle (Centaurea solstitialis), an important late season honey crop for beekeepers in my region. (See Barthell et al. 2001) I suspect this type of mutualism is much more common than we currently know.

Dipsacus fullonum with Bombus vosnesenskii
The plants are quite interesting, and if it weren't for their invasive nature I would grow them myself. They are taprooted with some roots reaching nearly two feet deep and an inch in diameter at the crown. Leaves are opposite and sessile, clasping the stem to form cups which can fill with water when it rains. This is hypothesized to protect the flowers from crawling nectar thieves or perhaps sap-sucking insects from climbing up the stem. The plants are biennial or monocarpic perennials, which means they die after flowering. They may have been introduced intentionally for use in the textile industry as early as the 1700s, or perhaps it was introduced accidentally or brought as an ornamental. In either case it is probably here to stay.

Hypochaeris radicata
Another invasive, not solely subjected to agricultural land, catsear (or false dandelion) is an abundant European native. They are perennial growing from thick fleshy taproots that break easily when pulled and regenerate into multiple crowns when disturbed. The seed goes airborne when it is ripe, or is perhaps distributed by birds. The flowers open when the sun comes up and close if it gets hot out, though I'll admit to not knowing the exact threshold at which this occurs. Collectively they bloom for the entirety of summer and into the first half of autumn, and are highly attractive to bees of various types. My employer has a sizable apiary located in this field, and I have personally observed multitudes of honeybees visit the flowers.

Hypochaeris radicata in the bee yard
I have mentioned in previous posts (see Apiaries, Apiaries II, & Apiaries III) that I work for a commercial beekeeping operation, and thus I am in the delightful position (literally) to view the bees at work. I have noticed that where there are many hives, there does not seem to be an abundance of native bees (with the exception of bumblebees). I am slightly at odds with honeybees, though I cannot argue their importance to us as we are today. The problem, I find, is that far too much prestige is placed on the honeybee while little to no attention or thought is given to the native bees. The reason we need honeybees to the extent that we do is because we have in many cases destroyed the habitat and food sources of many of the native bees (not to mention the other pollinators and other beneficial arthropods) in many parts of the country, creating places that are largely devoid of naturally occurring life (what does live there, we have put there). Honeybees directly compete for resources with the native pollinators, something that should be intuitive since plants are limited to the quantity of pollen and nectar they can produce per day.

The preeminence of honeybees is not without its benefits, as they are the poster children of environmental consciousness today. They are the martyrs of the current cultural trend towards pollinator conservation, and for that they deserve great credit. I myself would not be writing this today if it weren't for the honeybee, nor would I have one of the best jobs in the world. And I truly love my job!

Another day at the office!


  1. Hi Travis, great post, love your stuff, I'd like to be able to identify more of the many pollinators I get in the garden, what are the best books/articles to look for, I know you refer to some above, but I'd like some sort of ranking if possible. You can reply to my e-mail address if you'd prefer. Robin.

    1. Thank you Robin, I've updated my Suggested Reading page to include a basic rating system. Have a look:


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