Holiday gift ideas to spread the pollinator love

As you start (or finish?) your holiday shopping, here are some gift ideas to spread the love of pollinators.

For beginner and/or experienced gardeners

32 Plant Pollinator Garden, photo from prairienursery.com
  • Bee hotel/DIY kit: Bee hotels are a fun and easy way to support native bees in your own backyard or garden. While most people think about honey bees when they think “bee,” 90% of bee species nest alone in tunnels or holes. Putting out a bee hotel near your garden will provide more real estate for these bees. Here is a list of various bee hotel options.  
  • Pollinator introduction kit: This kit from Prairie Moon Nursery includes Pollinator Palooza seed mix (the mix we give out), a bee hotel kit, and a book on attracting native pollinators.
  • Pre-planned garden: For those who would like a pollinator garden but don’t want to do the planning, Prairie Nursery (not to be confused with Prairie Moon Nursery) sells a variety of pre-planned pollinator gardens complete with plants, planting instructions, and a design map. All gardens include a variety of perennials that will keep your garden blooming (i.e. providing food for pollinators!) from spring through fall.

For readers

Metallic green sweat bee, photo taken by Rachael E. Bonoan
  • Subscription to 2 Million Blossoms: The gift that will keep on giving through 2020, 2 Million Blossoms is a new quarterly magazine dedicated to transporting its readers to the world of pollinators. In the first issue, readers will get “distracted by bees” in my photo essay about bees on a Pacific Northwest prairie, like the brilliant green sweat bee, and the wildflowers they visit.
  • The Bees in Your Backyard by Joseph S. Wilson and Olivia Messinger Carril: This is one of my favorite books about bees! In this book, readers learn how to identify native bees that are likely in their backyard (in North America) and what they can do to help the bees. Gorgeous photos accompany easy-to-read text.
  • Honeybee Democracy by Thomas D. Seeley: My love for insect pollinators started with honey bees. Although they are not native to North America and are more of a domesticated animal than a wild pollinator, we can learn a lot about our native pollinators from studying honey bees! In this book, honey bee biologist Tom Seeley describes the amazing ways in which honey bees work together to make decisions as a group.

For foodies

Photo from proudpour.com
  • Honey: Raw honey is one of the sweetest gifts to give (pun very much intended). You can often find local beekeepers at holiday craft fairs selling their delicious honey (sometimes gorgeous beeswax candles too!). If you can’t make it to a craft fair or they’re just not your thing, there are companies that will ship raw, delicious honey right to your door! Some of my favorites are: GloryBee, Boston Honey Company, and Savannah Bee Company. If you’re local to the Boston Area, check out Follow the Honey , a brick-and-mortar where you can find (and taste!) honeys from New England and around the world. Honey varietals make great gifts—that friend from Canada will go crazy for Canadian White Gold.
  • Save the Bees Pinot Noir: Proud Pour’s Pinot Noir from Oregon will pair beautifully with that holiday roast chicken. As a bonus, proceeds go towards replanting wildflowers on farms local to where the wine is purchased!
  • Beeswrap: I love my beeswrap! An environmentally friendly alternative to the plastic baggie, beeswraps are fun fabrics coated in beeswax that are washable and reusable, and perfect for wrapping up that sandwich or snack. Beeswrap can also be used in place of plastic wrap to cover and store leftovers.

For fashionistas

Cast honeycomb hoop earrings, photo from beeamour.com.
  • “Plant these” long-sleeved shirt: Support pollinator-friendly gardening as well as an artist with this adorable shirt from Etsy.
  • “Protect the pollinators” short-sleeved shirt: While TPI mainly focuses on insect pollinators, this shirt spreads pollinator love by including hummingbirds and bats in addition to insects.
  • Bee Amour jewelry: Made by a beekeeper in Texas, this jewelry is inspired by some of our most well-known managed pollinators, honey bees. Some of the pieces are even cast from actual honeycomb!

For the person who doesn’t need anything

Happy holidays from TPI!

Why you should leave the leaves (and give yourself a break from yard work!)

by Jessie Thuma

Fall is finally here, and with it comes a sense of new beginning and fresh starts. There’s no better time to try something different, and what better place to start than in your own backyard? This year, start a new tradition: stop the raking and leave the leaves to reclaim habitat for the bees, butterflies, moths, flies and beetles that we rely on for pollination!

In 2005, NASA estimated about 40 million acres of U.S. land are devoted to turf lawns, making lawns the largest managed “crop” in the country—and the largest potential pollinator habitat. Pollinators move pollen from plant to plant, keeping flowers blooming in gardens and food growing on farms year after year. But the plants we depend on for food, raw materials, oils, and textiles, require abundant and diverse pollinator populations. As native pollinators decline, in large part due to habitat and floral resource loss, our backyards are the perfect place to start strengthening pollinator communities.

Bombus impatiens taking shelter under fallen leaves

Leaves and plant litter are critical habitat for overwintering pollinators. A mini-ecosystem starts to grow when we minimize yard work: butterflies and moths lay eggs on the undersides of fallen leaves and seek shelter under leaf cover as the days get colder; solitary bees build nests in dead plant stems and old woody material for nesting sites; bumblebee queens hibernate in shallow holes just a few inches below the soil until warmer spring weather arrives. Keeping your lawn pollinator-friendly is cheap, effective, and requires less effort than maintaining the standard leaf-free lawn. By letting nature take its course, we can increase backyard biodiversity and boost pollinator communities that will bolster gardens in the spring!

Native pollinators, including butterflies, bees, and flies, are important to the function of every ecosystem. If you want to support our pollinators, follow these tips:

  • Leave the leaves where they fall. Leaf litter provides habitat, insulation, and protection for insect pollinators. It’s also a natural fertilizer for grass as leaves break down during the winter.
  • If you can’t leave all the leaves, rake lightly without disturbing the soil. Avoiding soil disturbance or rough handling of leaves will ensure that any hibernating insects stay buried and any butterflies or larvae sheltering under leaves are not killed.
  • Pile leaves over garden beds, around trees and shrubs, or in the corner of the yard. Keeping leaves intact will still provide pollinators like butterflies with shelter and overwintering sites. Keep the leaves where they are until the weather warms and any pollinators using the leaves have emerged to start foraging. Bonus: leaves serve as natural mulch for your garden, so you can save pollinators AND money!
  • If you choose to remove leaves from your yard, always compost your yard waste. Yard waste produces a greenhouse gas, methane, when left to decompose in landfills without enough oxygen. When burned, yard waste can pollute the air or lead to uncontrolled fires in dry areas. Go online or make a phone call to your local Department of Public Works to find out if curbside yard waste is composted, or to find the nearest compost center near you.

Neighbors upset by the piles of leaves? Explain to your neighbors how leaving the leaves is an easy way to do your part in pollinator conservation—maybe they will want to join you!

PC: Franklin Park Zoo

Have the itch for yard work but want to help the pollinators? Plant native flowers (or a whole pollinator garden) to make your yard a pollinator hotspot year-round!

Have more questions? Check out this blog post by the Xerces Society to read more about leaving the leaves.

If you like pumpkins, thank squash bees

Nothing says fall quite like pumpkins. They feature prominently in seasonal pies and Halloween decorations. Contests are held and won at county fairs by the farmers that can grow the largest pumpkins (some weighing in at more than 2000 lbs). Their appearance on the shelves of stores and farm stands marks the start of a season of aster and goldenrod, of cold nights and falling leaves, of root vegetables and mulled ciders. Amidst all this pumpkin hubbub, it is easy to take for granted our favorite orange squashes and lose sight of where they come from.

All pumpkins are a single species of squash, Cucurbita pepo, which is a scraggly vine native to the desert southwest. Over thousands of years, C. pepo was transported across North America and diversified through careful cultivation by native peoples and modern agriculture into many of the squash cultivars we love today: acorn, spaghetti, delicatta, and pumpkins. But it wouldn’t have been possible without some (tiny) help along the away.

Earlier in summer, this patch of ripe pumpkins was a field full of flowers and wild bees. Pumpkins are dependent on bees for pollination, and a single species of squash bee (Eucera pruinosa) perform the lion’s share of the work in New England. PC: Public domain

Every pumpkin starts out in mid-summer as a female squash flower, a yellow starburst peeking through huge green paddle leaves. Squash plants are monoecious (mon-ee-shus), meaning that male and female parts occur in separate flowers on the same plant. So, one squash plant contains flowers that produce pollen (male) and others that produce ovaries (female). In order for a female flower to be fertilized and successfully produce a fruit (yes, all squash are fruit), pollen from the male flowers must be transferred to the female flowers. This is pollination.

In natural and agricultural systems, wild bees are the main transporters of squash pollen. Early in the morning, squash flowers open up and produce prodigious quantities of sugary nectar to attract pollinators. Once in the male flower, the bee is passively dusted by squash pollen which it transfers to the next female flower that it visits. And so on and so forth until afternoon when the squash flower closes, never again to reopen. Hopefully, during its single day of blooming, it received a visit from a bee!

Squash bees (Eucera pruinosa) are important pollinators of pumpkins. Here you can see one lapping up nectar at the base of the flower. PC: Flickr

Which bees, however? Squash bees (!), so called because they feed their offspring exclusively with squash pollen (plants in the genus Cucurbita). There are around 20 species of bees that specialize on squash, but in New England we have just one: Eucera pruinosa (formerly Peponapis pruinosa). But, this bee is not historically native to New England. Recent genetic analyses show that squash domestication and trade over thousands of years enabled the squash bee to colonize New England from the desert southwest via the Great Plains. Thus, the squash bee exists in New England solely because humans are unwavering in their love for squash. You can think about this in another way: if all of New England were to stop growing squash for a single year, squash bees would be swiftly extirpated from the area.

Since squash bees are pretty picky about the pollen they consume, their seasonal activity period is limited to peak squash flowering season in Massachusetts, generally from mid-July to early August. Males emerge first and quickly establish territories at the best place to find a female squash bee: squash flowers! Although male solitary bees are often considered only useful as mates, because of this behavior, male squash bees are uncharacteristically good pollinators; they contribute heavily to the $200 million annual industry of pumpkin production.  

Once mated, female squash bees build their nests at the edges of squash fields in bare, packed soil. Because they are solitary, every female builds and provisions her own nest, though often nests will occur in close proximity to one another. She excavates a narrow tunnel through the soil, and every day prepares a chamber, fills it with a stiff oval of squash pollen and nectar (think play-doh consistency), and lays a crescent-shaped egg. This chamber contains everything the young squash bee needs to develop from egg to larva to adult. Squash bees will spend the winter underground and won’t emerge until the following summer when squash is flowering again.

Squash bees are solitary, meaning each female build a single nest underground. And the end of each side tunnel, she provisions a single offspring with pollen and nectar from squash flowers. Adult squash bees are active only for four-six weeks in late-summer. PC: Chan et al. (2019) Sci. Rep. 9: 11870.

How good are squash bees at making pumpkins? So good that many farmers refused to believe it. Historically, squash pollination was supplemented with commercial hives of honey bees and, in some cases, bumble bees. Yet, it has been shown that farm fields supplemented with managed bees do not produce bigger yields than ones receiving only wild pollination. There are two explanations for this. First, most other bees refuse to collect squash pollen for their offspring, possibly because of distasteful chemicals. Thus, managed bees are only visiting squash flowers for nectar and come into less contact with pollen. Second, squash bees are such efficient foragers and their daily schedule so synchronized with the daily schedules of squash flowers, that by the time other bees arrive, the flowers have already received sufficient visits to produce big pumpkins. Still, many farmers bring in managed bees to pollinate their pumpkins as an insurance policy.

This Halloween, if you carve a pumpkin or drink a spiced latte, thank squash bees. Our obsession with pumpkins enables these abundant pollinators to survive and grow in the most unlikely of places (even in the middle of Medford), and their unrelenting obsession with cucurbit pollen gives us more pumpkins than we know what to do with.

P.S. If you want to get a close up look at a squash bee, one afternoon, late next summer, find a closed squash flower in a garden. Chances are that a male squash bee is dozing inside, perhaps having found a mate that morning or just missed his opportunity. Look for goofy-long antennae, ochre hairs, and a boldly striped abdomen.

Providing shelter for native bees

Last month I had the opportunity to run a workshop on protecting native bees for 250+ kids at Camp Micah in Bridgton, ME. Like humans, bees need three things: food, shelter, and water. In my workshop, the campers focused on shelter—we built 200 bee “hotels” to donate to the Honeybee Conservancy for their Sponsor-A-Hive program.  

We hear a lot about honey bees, which make their homes in hives, but most bees are solitary and make their homes in less conspicuous manner. Mining bees (Andrena species), as their name suggests, make their home by digging tunnels in bare soil. In addition to digging tunnels, cellophane bees (Colletes species) line their nests with a clear protective secretion that resembles…you guessed it..cellophane! To provide shelter for these types of bees, leave your garden un-mulched.

Hanging by a couple of our research hives, typical man-made honey bee hives, at Cummings School of Veterinary Medicine at Tufts University. Photo: Rachael E. Bonoan
Blue orchard mason bee (Osmia lignaria) female.
Photo: USGS Bee Inventory and Monitoring Lab

Mason bees and leaf-cutter bees also nest in tunnels, but they do so a bit differently. These bees use ready-made tunnels in wood, hollow sticks, or dried-out plant stems. Female mason and leaf-cutter bees collect pollen and nectar to make a “food ball,” which she shoves to the very bottom of the nest. She then lays an egg on top of this food ball and makes a divider out of either mud (mason bees) or leaves (leaf-cutter bees). The momma bee then collects materials to make another food ball, which she puts in front of her “divider,” lays another egg, and the cycle continues until the nest is full of food and baby bees.

Cross-section of a blue orchard mason bee (Osmia lignaria) nest with mud dividers, orange-yellow food balls, and bright white bee eggs.
Photo: USDA ARS

The baby bees hatch out of their eggs, eat their nutritious food ball and develop from larvae, to pupae, to adult. In mason bees, pupae spin a cozy cocoon in which they complete their development to adult. The adult mason bees stay inside their cocoon until the weather is just right. In early spring, they chew their way out and emerge into the bright new world. To provide shelter for these bees, leave some of the larger, dried out stems in your garden. Or, like the campers, you can make a bee hotel!

Bee hotels don’t have to be five-star. They can be as simple as taking some dried out stems or reeds, creating a bundle, and securing the bundle with twine. You can hang this bundle somewhere near your garden (where the bees have food!) or in a tree. A variety of tunnel sizes ensures a variety of bees can use your bee hotel—bees come in many shapes and sizes. To provide enough space for the momma bee and her babies, the tunnels should be about 4 – 10 mm in diameter and about 15 cm (6 inches) long. If you don’t have dried-out stems readily available, you can purchase small cardboard tubes or paper straws to make your bundle. Avoid using plastic straws or bamboo as they don’t let the nutritious food ball breathe and may harbor mold.

You can add some amenities to your bee hotel in the form of PVC. A piece of PVC pipe 2 – 4 inches in diameter and a few inches longer than your tubes allows for some protection from the elements. Simply place a cap at one end of the PVC and pack your tubes in until they fit snugly. Again, use twine or if needed, zip ties, to secure your bee hotel. To keep birds and other possible predators out, you can add a security system with 1-inch wire mesh loosely secured to the front of your bee hotel. If possible, face the entrance of your bee hotel to the south so the bees get lots of warm morning sun (and a nice view).

When constructing your bee hotel, think about making it as big as the food (flowers) in your general area will support—you don’t want to raise too many bees and not have enough food. A meadow of wildflowers can support more/larger bee hotels than a small urban garden. To avoid spreading disease, replace the hotel’s linens (the tunnels) every year or two. In March and April, watch the entrance to your bee hotel to see how many bees emerge!

Fierce and fascinating solitary wasps

In mid to late summer in the northeastern US, several species of large solitary wasp (belonging to the families Sphecidae and Crabronidae) frequent gardens, parks, and other open spaces. Despite their threatening appearance, these conspicuous insects are not aggressive and pose little danger to humans. As predators, they provide a valuable service by helping keep populations of other invertebrates in check. Solitary wasps are carnivores that capture and paralyze insects or spiders to feed their young, with many species specializing on particular types of prey. Unlike hornets, yellowjackets, and other social wasps, solitary wasp females build and provision nests independently of one another. Nesting locations differ among species and may include a variety of cavities both above and below ground.

Great Black Wasp (Sphex pensylvanicus) nectaring on Hairy Mountain Mint (Pycnanthemum verticillatum var. pilosum)

Digger wasps in the genus Sphex nest in the ground. In the northeast, the Great Golden Digger Wasp (Sphex ichnumoneus) and Great Black Wasp (Sphex pensylvanicus) are two particularly common species that can be seen drinking nectar from milkweeds, mountain mints, and other flowers. Females hunt katydids, stinging and paralyzing their prey before dragging it back to the nest. Although they are solitary, digger wasps sometimes aggregate, with many females constructing nests in close proximity. Each nest consists of a main tunnel with a number of side tunnels, each of which ends in a brood cell in which an egg is laid after the cell is provisioned with several katydids. When bringing paralyzed prey back to the nest, female Sphex leave the prey item outside the nest entrance while investigating the nest interior before dragging the prey down. If the prey item is moved slightly, the wasp will retrieve it and inspect the nest yet again. Sphex’s automatic nest-checking routine has captured the attention of several philosophers interested in the contrasting ideas of instinct and free will, inspiring the coining of the word “sphexish” (used to describe actions that appear thought-out and deliberate but are instead actually quite mindless).

Golden Digger Wasp (Sphex ichnumoneus) nectaring on Hairy Mountain Mint (Pycnanthemum verticillatum var. pilosum)

Isodontia grass-carrying wasps are a common sight around houses, gathering dry blades of grass and stuffing them into a crevice to furnish a nest. Grass-carrying wasps are predators of katydids and tree crickets and, like the digger wasps, leave their prey alive, but paralyzed, for their larvae to feed on.

Grass-carrying Wasp (Isodontia sp.) nectaring on Hairy Mountain Mint (Pycnanthemum verticillatum var. pilosum)

The giant cicada killer wasps (Sphecius sp.) are hard not to notice. Reaching lengths of an inch or more, these are among the largest wasps in North America. Even so, these formidable-looking insects are typically harmless. Females are not aggressive and although males may behave aggressively, they are unable to sting. Cicada killers sometimes form nesting aggregations, with many females utilizing the same patch of bare soil while males hover about looking for opportunities to mate. As their common name suggests, cicada killers hunt cicadas, paralyzing them and then flying back to their nest while carrying a prey item heavier than themselves. The wasp larva consumes the cicada and emerges as an adult the following summer.

Cicada Killer (Sphecius sp.)

Other solitary wasps hunt soft-bodied prey. The thread-waisted wasps in the genus Ammophila are a group of impossibly-skinny caterpillar predators. They can often be seen flying with a caterpillar slung underneath their body, toting their paralyzed prey back to an underground nest. Interestingly, after completing their nests and filling the tunnel with sand, some thread-waisted wasps have been observed using a small stone held between their jaws to tamp down soil at the former nest entrance, a behavior sometimes considered to be an example of tool use!

Thread-waisted Wasp (Ammophila sp.) with caterpillar prey

Though they may lack the charisma of butterflies, bees, and other favorite garden insects, solitary wasps are a diverse group that play an essential part in regulating numbers of herbivorous insects. By leaving patches of bare soil for nesting and planting milkweeds (Asclepias sp.), mountain mints (Pycnanthemum sp.), joe-pye weeds (Eupatorium sp.) , and other favorite nectar plants, you can encourage the presence of these beneficial insects in your yard and enjoy their pest-control services and enthralling behaviors.

Photo Credits: Max McCarthy

The butterflies who are raised by ants

Written by: Atticus Murphy

Silvery blue caterpillar. Photo: Atticus Murphy

What are these ants doing, clustering around a caterpillar? If you guessed eating, you’d be right, but probably not in the way you imagined.

These ants are engaged in what’s called “tending,” and far from being harmed by the interaction, the soft and vulnerable caterpillar is likely a beneficiary. In fact, the caterpillar has a suite of complex adaptations that seem aimed at keeping ants nearby. Most striking among these is the dorsal nectary organ, a gland that secretes a nutritious liquid high in sugar. Foraging worker ants eagerly consume the food and bring it back to their colonies. The cost to the caterpillar is only the cost of producing these little nutrition packets.

A less attractive ant and a silvery blue caterpillar. Photo: Atticus Murphy

But why would a caterpillar want a murderous cadre of ants clustered around it? The answer is protection. For one thing, when you manage to get the bullies on your side, they won’t bully you anymore: that is, the pacified ants are no longer a threat to the caterpillar. And in general, being a caterpillar is very dangerous. They have soft bodies, often feed in the open, and are not known for their quick movement, making them easy prey. In addition to being eaten directly, there are a huge diversity of parasitoids in the insect world, who lay eggs inside caterpillars’ bodies and eat their way out. This kills the caterpillar. A standing guard of ants, who generally protect their food sources and each other, lowers the caterpillar’s risk of being parasitized. Thus, because this interaction is often mutually beneficial, we call it a mutualism, meaning that both the ants and the caterpillars do better because of it: ants get food and caterpillars get protection.

Ants tending a silvery blue caterpillar, who is releasing a droplet from the dorsal nectary organ (the tiny glimmer in the center of the photo). This is located at the rear end of the caterpillar. Photo: Atticus Murphy.

In order to keep their attendants friendly, the caterpillar can also release a potent cocktail of chemicals that mimic ant pheromones, encouraging the ants to stick around, and hopefully keeping them from trying a bite of caterpillar. This cocktail is so effective that sometimes the ants can’t distinguish the scent of the caterpillar from their own kind. If the ants are absent and a predator approaches, some caterpillars also make use of specialized organs that produce noises or fragrances, attracting ants from farther away.

An adult female Silvery Blue lays an egg on lupine: within 3 days the egg will hatch, and within a week it will be old enough to attract ant attendants. Photo: Rachael Bonoan.

The butterfly species in the pictures above is the one I worked with this summer, the silvery blue (Glaucopsyche lygdamus). It’s common across the U.S., but this interaction is a global phenomenon, occurring in hundreds of butterfly species that can be found on every continent except Antarctica. And with a diversity of species comes a diversity of interactions: many different ant-caterpillar pairings have emerged, and unique quirks abound. Perhaps the most captivating variations on the theme are the parasitic blue butterflies. These dastardly caterpillars have taken the usual mutually beneficial interaction and tilted things decidedly in their own favor by truly pretending to be baby ants. After spending some time feeding on a host plant like most caterpillars do, these species use their unusually effective chemical mimicry to induce ants to take them inside the actual nest, where the caterpillars are either fed alongside the real ant young, or more sinisterly, the caterpillar devours the ant young, growing fat by pillaging their hosts until they’re ready to emerge as adults.

The Large Blue butterfly, a parasitic relative of the Silvery Blue. Photo: Ann Collier.

The ant-tending of these butterflies is not just an interesting quirk of natural history, but for some species may be the key to their continued existence. The classic example of this possibility is the large blue butterfly (Phengaris arion) of Britain, which is a parasite of Myrmica ants. This butterfly was on the decline for decades in the British Isles and was an early beneficiary of an intensive conservation campaign. Unfortunately, this campaign failed, and by the 1970s, the species teetered on the edge of extinction in spite of years of efforts. The conservationists were perplexed. They had carefully cultivated healthy patches of the host plant, Thymus, and there looked to be plenty of ants in the area, so why were the butterflies still declining?

It took a careful reexamination of the already well-known dependence on Myrmica ants to understand what had occurred. The large blue was an unrecognized specialist, a butterfly who relied not just on Myrmica ants to survive, but on a particular species of Myrmica ant. This species was so crucial that even close relatives were totally unsuitable and could not successfully “raise” caterpillars to adulthood. While there were indeed plenty of Thymus plants and plenty of Myrmica ants, the ants were of the wrong species! The large blue tragically went extinct in Britain before this new knowledge could be put in practice, but it has since been successfully reintroduced.

So, the next time you see a blue butterfly, remember that it might well have relied on an unruly bunch of ant nannies to survive into its winged form. Remember also that these butterflies provide still another example of the myriad ways in which our pollinators are dependent on an entire healthy ecosystem and its component parts, not just on their host plants.

Further Reading:

Pierce, N. E., M. F. Braby, A. Heath, D. J. Lohman, J. Mathew, D. B. Rand, and M. A. Travassos. 2002. The ecology and evolution of ant association in the Lycaenidae. Annual Review of Entomology 47:733–771.

Thomas, J. A., D. J. Simcox, and R. T. Clarke. 2009. Successful Conservation of a Threatened Maculinea Butterfly. Science 325:80–83.

For the love of (wild) lupine

If you’ve ever driven through New England in June, then you’ve probably also, somewhere in the middle of verdant nowhere, come across a sea of lupine lapping the roadside. Flowers as far as the eye can see is an indelible view, one that’s hard to come by on the east coast. So, it’s no wonder why New Englanders seem to have an inordinate fondness for lupine. New Hampshire boasts about its must-see lupine through tourism campaigns, memorabilia, and open-air craft markets. In more than one state, entire celebrations are devoted to this existence of this plant. And both the real and fictitious Miss Rumphius sought to spread its violet steeples along the Maine coast. There’s only one issue: this beloved lupine is invasive.

A field of the invasive bigleaf lupine (Lupinus polyphyllus). Still, Miss Rumphius would be proud. PC: Rabbit Hill Inn.

Bigleaf lupine (Lupinus polyphyllus) is native to western North America but has colonized disturbed roadsides of New England as well as much of northern Europe. Even though, like all lupines, it enriches poor soils with nitrogen which could facilitate the growth of other plants, the opposite has been found; in areas where bigleaf lupine grows, it dominates. But that sea of flowers supports pollinators, right? Wild bees definitely take advantage of its pollen resources (its flowers lack nectar) while it flowers, but since a field of lupine often contains few other flowering plants, they will have to fly further to find food the rest of the year. Even more troubling is that no butterflies and moths in the east share an evolutionary history with bigleaf lupine, so their caterpillars cannot develop on its leaves. In places where bigleaf lupine is invasive, this ecological incompatibility has been found to reduce the local abundance and diversity of lepidopteran pollinators.

There is, however, a native lupine that plays an important role in supporting New England’s insect pollinators. Enter wild lupine (Lupinus perennis). This equally (if not more, but maybe that’s just me) attractive lupine thrives in sandy, xeric plains that are transitioning from grassland to forest. In New England, this often equates to powerline rights-of-ways or intentionally managed reserves, where wild lupine depends on insect pollinators, mainly bees, to reproduce. Bumble bees (Bombus spp.), carpenter bees (Xylocopa virginica), mason bees (Osmia spp.), leaf-cutter bees (Megachile spp.) are all capable pollinators, forcing themselves through the clamshell-like flowers to reach the reward (this lupine also doesn’t produce nectar). Notably, it is also supports three threatened butterflies in the region—karner blue (Lycaeides melissa samuelis), frosted elfin (Callophrys irus), and persius duskywing (Erynnis persius). Wild lupine is the sole food source for karner blue and persius duskywing caterpillars, and just one of two leguminous host plants of frosted elfin. Numerous other handsome Lepidoptera feed on its leaves during development including bella moth (Utetheisa bella) and phyllira tiger moth (Grammia phyllira).

Bumble bee foraging on wild lupine in Concord, NH. PC: Max McCarthy

Unfortunately, populations of wild lupine across its northern range have declined due to a combination of forest fire suppression, human development, and unbridled harvest. But don’t despair: there’s a deep-rooted interest in protecting wild lupine across its range at publicly accessibly locations. The USFWS Karner Blue Easement in Concord, NH boasts a small, but persistent population, and an impressive display can be viewed at Albany Pine Bush during their annual Lupine Fest in late-May. Across the border, High Park in Toronto is an excellent example of how fire-dependent plants (and ecosystems) can be managed alongside humans. If you visit either of the first two sites during summer, you’re might also spot karner blues dancing among the scrub. Remember that they are there only because wild lupine is there too.

Karner blue butterflies can develop on only one type of lupine: wild lupine. The common bigleaf lupine along roadsides does not support this endangered pollinator. PC: Justin Meissen, Flickr

I’m not proposing we launch a campaign to plant roadsides with wild lupine, nor am I saying that you should feel guilty about gawking at the bigleaf lupine through your windshield. Rather, know the latter plays a mostly aesthetic role, whereas the former an ecological one. And if you want to directly help pollinators that depend on wild lupine? Buy sustainably sourced seed and plants for your garden and support organizations and initiatives (like the ones listed above) focused on restoring its ephemeral habitat to ensure it’s around for future generations and pollinators alike to enjoy.

To support spring pollinators, think big

In summer, pollinators are not often hard-pressed to find flowers. In fact, you might support them without even knowing it: community gardens, flowering herbs on front steps and balconies, or milkweed growing in a tree-well all provide food for pollinators during the hottest, longest days of the year.

But what about in spring? It’s not as easy to accidentally support pollinators during these cooler months of the year when the ground has just begun to thaw; there haven’t been that many warm days; and persistent rain (as continues this year) can impede pollinators from finding food. Indeed, queen bumble bees emerge from hibernation in early spring and need immediate access to both nectar and pollen in order to start their colonies for the year, and many solitary bees and hover flies are only active for several weeks in spring: no flowers means these pollinators cannot make it.

So, how can you support pollinators in April and May? Think big. Plant native flowering shrubs or trees. In New England, you’ll be hard-pressed to find better forage for insects than these woody plants. Not only do these larger plants produce copious amounts of flowers, but they are often important host plants for caterpillars of moths and butterflies. Plus, with the exception of woodland wildflowers, there simply aren’t enough growing days by mid-spring for most smaller, herbaceous (soft-stemmed) perennials to flower.

In addition to supporting pollinators, serviceberry produces delicious berries enjoyed by both birds and humans.
PC: Ryan Hodnett, Wikimedia Commons.

Choose plants that bloom sequentially from April through early-June. By selecting plants with overlapping flowering times, you will support a high diversity of pollinators regardless of when they emerge. To help you decide, here are several hardy options of native trees and shrubs that support bees, followed by average flowering times in Massachusetts:

  1. pussy willow (Salix discolor, early-April)
  2. red maple (Acer rubrum, early-April)
  3. eastern redbud (Cercis canadensis, late-April/early-May)
  4. serviceberry (Amelanchier sp., late-April)
  5. chokecherry (Prunus virginiana, May)
  6. red elderberry (Sambucus racemosa, May)
  7. nannyberry(Viburnum lentago, May)
  8. black cherry (Prunus serotina, late-May/early-June)
  9. red osier dogwood (Cornus sericea, May/early-June)
  10. ninebark (Physocarpus opulifolius, June)
The eastern carpenter bee (Xylocopa virginica) is one of the many native pollinators that enjoy redbud flowers.

Although many ornamental flowering trees are pretty, the frills that we enjoy often do little to help pollinators. Even worse, some ornamental cherry trees sometimes lack pollen and/or nectar altogether, making them essentially useless to flower visitors. In contrast, many ornamental crab apple varieties (Malus sp.), though non-native, are one alternative that appeal to both humans and insects.

Wild cherry trees have five petals per flower, but this “doubled” ornamental produces copious petals (possibly at the expense of quality nectar and pollen) that dissuade pollinators from visiting the flowers.
PC: Yoshikazu Takada, Flickr

One last note: to further help early-spring pollinators in a different way, try “leaving the leaves” until early-May. It is tempting to clean up your yard as early as possible, but many insects overwinter as various life stages in the messy leaf piles and ground cover, e.g. butterfly eggs, chrysalises, and adults of different species. Give them a chance to emerge by delaying your clean-up a few weeks. You’ll be rewarded when all these beautiful pollinators return to visit the flowers in your garden!

How did the bees survive the Notre Dame fire?

You may have seen in the news that the three honey bee colonies on the roof of Notre Dame survived the tragic fire that destroyed much of the Cathedral. This was possible because honey bees are incredibly adept at maintaining the temperature of their hive and have developed behavioral mechanisms to survive in heated environments. The driving force behind hive temperature maintenance is brood protection. Honey bee brood (the eggs, larvae, and pupae that will grow into adult bees) can only develop properly within a specific temperature range. Too cold and they are more vulnerable to disease and parasites, too hot and they are likely to develop deformities which prevent them from performing hive duties as adults. Since adult honey bees only live for around thirty days in summer, it is critical that the brood are maintained at a healthy temperature to ensure the survival of the colony.

To survive the heat, honey bees have evolved three main behavioral strategies to cool their hive: fanning, heat shielding, and evaporative cooling.  In fanning behavior, honey bees fan their wings to create cool air currents that push hot air out of the hive. When enough bees start fanning the colony changes their position to create air current pathways which look rivers running between the bees throughout the hive. Paired with fanning, bees will induce a sweat like evaporative cooling effect by sucking up stored water and spraying it in hot areas of the hive.

The third major way that honey bees cool their hives is with a behavior called heat shielding. Honey bees usually stand with their body on their comb, and their backs to the hive wall. When the wall gets too hot, the bees will stand instead on the walls of the hive to absorb heat into their bodies.  Once individual bees get too hot they move to the edges of the hive where they dissipate the heat. By engaging in this behavior honey bees are able to act as mobile heat sink units, physically transporting heat within their bodies away from temperature sensitive brood. With these three behaviors honey bees can rapidly cool their hive from dangerously hot temperatures and survive extreme circumstances like the fire at Notre Dame.