August 18, 2022
Sometimes, a day in the field doesn’t go as planned. I had started out this morning thinking that it would be a pollinator identification day. The setting: Carol “Kate” Wilburn’s urban Missoula yard. Since 2019, Kate has been converting her lawn into a garden packed with fruit trees and wildflowers. There are apples, currants, peaches, and apricots growing with dozens of species of native plants. She wants to have a yard where she can grow food, create wildlife habitat, and hold educational programs. Today, I wanted to take a look at the wildlife habitat. In a cityscape dominated by asphalt and houses, what creatures show up when we plant native plants?
In spite of the summer’s heat, Kate’s yard has been a profusion of flowers this year. At this season, there are five plants in particular that stand out: purple coneflower (Echinacea purpurea), smooth blue aster (Symphyotrichum laeve), Rocky Mountain beeplant (Cleome serrulata), Missouri goldenrod (Solidago missouriensis), and Maximilian sunflower (Helianthus maximiliani). When I arrived here and saw this palette of pink, purple, and yellow, several questions came to mind. How much diversity could we find here? What patterns would we see?
Kate is not just an avid gardener, but also my mom. We’ve been talking for months about doing a blog post on the insects in her yard. It seemed like a great opportunity to combine a visit with a check-up on her garden. Were the native plants really providing habitat for lots of insects here, as we hoped?
The best-laid plans
The plan for this field day was simple. We would spend time focusing on each of these five plants, observing patterns of insect activity. We would also catch some of the representative flower visitors, sneaking up on them and popping them quickly into plastic vials. Just like I did with bumblebees last month, we would put the vials on ice in a cooler to let the insects chill. Then we would take photos of the chilled insects, identify them, and let them fly off.
The day was already hot when we started, with the sun near its zenith and the temperature climbing rapidly toward the 90s. We began with the purple coneflower. The insect-catching went well. Within 15 or 20 minutes, we had an assortment of bumblebees and orange skippers in plastic vials.
It was at the “identify them” stage that the plan started to go awry. Whether it’s a fluke of nature or some malicious taxonomic conspiracy, it seems that for every common species of skipper butterfly (family Hesperiidae), there is at least one other that looks nearly identical. We spent most of an hour cross-checking two different field guides, maneuvering recalcitrant skippers in a butterfly viewing cage, and debating. Eventually, we decided that the butterflies we were seeing were all a common, remarkably variable species, the woodland skipper (Ochlodes sylvanoides).
Bees and their identification
Then it was on to the bumblebees – and they weren’t much better. The identification keys I have require females, but most of these bumblebees were males. We tentatively identified them as Hunt’s bumblebees (Bombus huntii), but we couldn’t be sure.
We finally came upon a female bumblebee, her abdomen mostly black with a yellow band at the base. This one would be straightforward, I thought! The cheek length of a bumblebee is both one of the most important characters for identification, and also one of the most difficult to discern. Quite sure that I was seeing a cheek that was as long as wide, I reached a dead end in the key. Perhaps it was slightly shorter than wide? Or slightly longer than wide? She was already warming up and beginning to wiggle. I took various photos and let her fly off, hoping that in the future I might learn to identify her.
Then it came time to look at an even-smaller bee, her hind legs coated in pollen. I flipped to the right page in my identification guide and took her off of the ice. Almost immediately, she began to twitch and wake up. I only had time to get a few photos and admire her briefly before she flew off. I looked back at the key, feeling defeated. Did she have just one subantennal suture or two? Was her tongue long or short? Forget it! Maybe this is why bee biologists usually work with specimens, I thought.
I needed to adjust my expectations. Clearly, identifying all of these insects in the field was way more than we could reasonably achieve today. So instead, we did something that anyone can do in their yard. We watched flowers, took photos, and tried to distinguish different “species” in the field by shape, size, and appearance.
And although we ended the day with many questions still unanswered, what we saw was compelling. In Kate’s urban yard, each of these five plants is supporting a variety of insects. Each plant is unique, with its own community of pollinators. So come along with us on this journey: five plants, one afternoon, and a surprising diversity of insects in one small city yard.
Purple coneflower (Echinacea purpurea)
The purple coneflower is a crowd of pastel, magenta-and-orange flowerheads rising above roughly textured leaves. This species is one of those wildflowers that wouldn’t be here without some human help. Although its cousin, narrow-leaved coneflower (Echinacea angustifolia) is a Great Plains species whose range extends into eastern Montana, purple coneflower is a plant of eastern North America’s wet prairies and meadows.
Of the five plants we’re looking at today, this is the only one that isn’t actually native to Montana. In general, native plants are especially important for our local insects: the plants and the insects have been evolving together for millennia. Nevertheless, the purple coneflower is busy with bumblebees and orange skippers today. We also spot a few tiny bees that invariably seem to escape when we try to slip up on them with a vial.
Most of the bumblebees are those males with orange-banded abdomens that we tentatively identify as Hunt’s bumblebees (Bombus huntii). We also catch a female who remains a mystery, her abdomen boldly clothed in yellow and black.
Along with the bumblebees, an assortment of woodland skippers (Ochlodes sylvanoides) are nectaring here. This is a very common late-summer butterfly across much of the west. An adaptable habitat generalist, its larvae can develop on various native and introduced grasses. The adults visit a range of flowers.
A few more bees
In about 15 minutes of observation, we spot just a single honeybee (Apis mellifera) here. So honeybees are visiting the coneflower, but not very commonly.
We also manage to catch two small bees. The first is smaller than a raisin, her hind legs dusted with deep yellow pollen. Each segment of her abdomen is tipped with bands of fine white hairs.
The other bee is larger, also with a banded abdomen. Its eye is pale green and the tip of its abdomen bears a prominent, spiny structure.
Except for the small, white-banded bee, none of these visitors seem to be carrying pollen. Are they only collecting nectar from the coneflower?
Smooth blue aster (Symphyotrichum laeve)
The asters are busy clumps of pale lavender blooms, appearing feathery from a distance. The flowers are loaded with more nectaring woodland skippers, their tongues unfurled. The other common insects here seem to be a variety of medium and small bees. The most common are approximately raisin-sized. Like the smaller bee we found on the coneflower, they have white bands of hair across the abdomen. These bees are clearly females, collecting pollen on their legs. They make a barely audible hum as they buzz busily from flower to flower.
We spot another species that looks similar but is clearly smaller. From time to time, we also see a few bees with remarkably long antennae here.
The asters are very active with all of these takeoffs and landings. Just on these two plants that we’re watching, we’re seeing probably a dozen skippers. At any instant, there are close to forty bees on them.
Unlike honeybees and bumblebees, these are very likely solitary species, each female provisioning her own nest with pollen and nectar to feed her young. Honeybees get lots of press, but the diversity of solitary bees is incredible. Many of them are raisin-sized or smaller, like those we’re seeing here. Lots of them nest in the ground; others nest in hollow plant stems. And the fact that they’re here, in urban Missoula, tells us that these species are finding what they need to survive. I wonder how far they’ve flown to find these flowers.
Seeing the diversity
We keep spotting additional species. There’s a little bee – or is it a wasp? – with a grayish abdomen, yellowish legs, and some yellow markings on the face.
Another bee looks like the green-eyed spiny one from the coneflower. We can’t know for sure without collecting both, but it seems likely that they’re the same species.
Nectaring alongside all of the woodland skippers, I notice a different butterfly. It’s similar to them in size and shape, but has much crisper white markings on the orange-green hindwing. I catch it for a closer look. After much study and debate, we decide that it’s probably a common branded skipper (Hesperia comma). Or could it be a western branded skipper (Hesperia colorado)? In either case, it’s another widespread member of our late-summer butterfly fauna. The caterpillars feed on grass, and the adults find nectar on a variety of flowers.
Rocky Mountain beeplant (Cleome serrulata)
The beeplants have already been blooming for weeks, but there’s no end in sight. The pale purple flowers, with their long, protruding stamens, surround tight clusters of darker, unopened buds. These plants are annuals, growing from seed each year. Nevertheless, they’ve thrived for several years now in Kate’s yard, reseeding happily. Some of this year’s plants are as tall as I am.
These flowers are by far the most popular today with the honeybees (Apis mellifera). But this afternoon, we’re not seeing very many other insects visiting them. Compared to the smooth blue aster, the activity level here is basically nothing. We spot a single woodland skipper. There’s the occasional medium or small bee that flies off before we can get a good look. I also notice several shiny ants crawling around on the stems and unopened flower buds. What are they doing? They don’t seem to be visiting the open flowers.
Watching the bees
As always, observing insects in the field is humbling. There’s so much more out here than what we can photograph or catch. A bumblebee moves briefly from flower to flower. Its abdomen is mostly yellowish, and I suspect it may be a white-shouldered bumblebee (Bombus appositus). I decide to try for photos instead of catching it in a vial. It bounces from flower to flower and I follow it with my camera, just a little bit too far behind. Then it flies off, and I have neither the bee nor its photo.
I watch the honeybees here more closely. Their pollen baskets are empty, and they seem to be poking their heads deep inside the flowers instead of paying attention to the widely spreading stamens. They aren’t bothering with pollen; presumably they’re collecting nectar here.
A black and white wasp is flying from cluster to cluster. But like the ants, it’s paying attention to the flower buds rather than the flowers themselves. It’s another mystery that we won’t unravel today.
Missouri goldenrod (Solidago missouriensis)
The goldenrods are sprawling, enthusiastic fountains of yellow covered in the activity of various small insects. Many of the plants are knee-high, evidently appreciating the water here. In their usual, sun-baked grassland habitats, Missouri goldenrod stays much shorter.
Wasps are common here this afternoon. I catch a prominently striped, yellow and black species: probably a predatory wasp in the family Crabronidae. If I’m right about the family, these are wasps that specialize in hunting various other insects. Some hunt beetles, some hunt caterpillars, and some even hunt other wasps and bees. They carry their prey to their nests, providing food for the larvae. The adults, on the other hand, feed mostly on flower nectar.
Another wasp is a little bit larger and blacker. A broad, prominent yellow band crosses the abdomen, which comes to a distinct point. These wasps are more skittish than the bees, and it’s difficult to catch them.
We see the occasional, medium-sized pollen-collecting bee here, resembling those we found on the smooth blue aster. There are also several well-camouflaged, speckled tan bugs visiting these flowers.
Maximilian sunflower (Helianthus maximiliani)
Almost as tall as the beeplants, these perennial sunflowers form vigorous, upright patches with bright yellow flowerheads and sandpapery green leaves. The sunflowers in this yard are a bit of a botanical mystery. They were sold as Maximilian sunflower, and seem to have some characteristics of that species, a native of eastern Montana. But while Maximilian sunflower leaves are usually folded in half along their midvein, like small green canoes, these leaves are more relaxed. This makes them look more like Nuttall’s sunflower (Helianthus nuttallii), a common species in our intermountain part of the state. In either case, these are striking plants. And the bees seem to be loving them.
We catch a medium, hairy gray individual with sky-blue eyes. Another one, densely covered in white, has hairy scoops on its forelegs.
There are several tiny bees with blunt abdomens. A couple more woodland skippers and what appears to be another Hunt’s bumblebee are visiting these yellow blooms.
One bee has extremely long antennae, green eyes, and a stiff covering of hairs. Another is small and narrowly cylindrical, with yellow markings on the legs.
Bees and beetles
A few of these bees – like the one with the long antennae – seem similar to species we saw earlier on the smooth blue aster. But many of these bees are new to us today. As with the other five plants, the insect community on the sunflowers is largely unique.
Kate spots a solitary beetle, medium-sized and brassy-haired, on the sunflower blooms. This is a blister beetle (family Meloidae), probably Epicauta ferruginea or one of its close relatives. The adults feed on the foliage and flowers of sunflowers and related plants – but the larvae are specialized predators in the soil, hunting down grasshopper egg pods and feeding on the eggs. Grasshoppers are rare in the middle of the city, so this blister beetle is a special find.
One urban Missoula yard, surrounded by asphalt and lawns. Four species of native plants, and one immigrant from the tallgrass prairie. What we’ve seen today is just a glimpse of this community, but it’s a tantalizing one. Each of these flowers is different – not just to our eyes, but to the insects’ eyes, too. Each patch holds its own stories of the pollinators it supports. For the purple coneflower, it’s the stories of nectaring bumblebees and woodland skippers. The smooth blue aster supports more skippers and a variety of pollen-collecting bees. The Rocky Mountain beeplant is feeding honeybees, ants, and a smattering of less-common visitors. For predatory wasps, the Missouri goldenrod is proving important today. And the Maximilian sunflower is harboring yet other species of bees.
There’s so much more we could ask here. Which bee and wasp species have we seen today? What are their life histories? Are they floral generalists or specialists? Twig nesters or ground nesters? But to answer those questions would take a much more intensive project, or someone much more skilled with bee identification than I am.
The bees and their flowers
We can’t answer those questions today. But anyone can go out in their yard and do this. Anyone can glimpse the sorts of general patterns that we’ve seen. In Kate’s yard, it seems, each of these flowers is adding something unique to the pollinator habitat that’s present. And they aren’t growing in isolation: there are also fruit trees, vegetables, and dozens of other native plants here. Some bloom earlier, some later.
The plants in this yard have only been here for two to three years now. But already, by spending part of a single day looking at five flowering plants, we’ve tallied 21 species of insects on these blooms.
It would take more sleuthing to learn the full stories of the insects we’ve seen today. But anyone can plant native flowers in their yard. Anyone can go outside, sit next to a patch of blooms, and spend a few minutes getting acquainted with the insects they’re attracting to our yards.
And if you’re looking for a few more beautiful, hardy native plants to boost pollinator diversity in your yard, here are some ideas.
Glassberg, J. (2001). Butterflies through binoculars: the west. Oxford, UK: Oxford University Press.
Montana State University. (n.d.) Bumble bees of Montana. Retrieved from http://mtent.org/projects/Bumble_Bees/key_female.html
Pyle, R.M. (2002). The butterflies of Cascadia. Seattle, WA: Seattle Audubon Society.
Wilson, J.S. & Carril, O.M. (2016). The bees in your backyard. Princeton, NJ: Princeton University Press.