Thanks for a great #PollinatorWeek!

Thank you all for a fun week of pollinator enthusiasm and engagement on social media! We’re closing out the week with a fun video by James, another new member of TPI, on the Baltimore checkerspot butterfly!

Miss any of this week’s fun? Check out the links below!

Monday: Bee hotels and Pollinator BINGO! (all week)
Tuesday: Pollinator-related recipes
Wednesday: Pollinator personalities (a quiz!)
Thursday: A look at our gardens, NEW native shrub planting guide
Friday: Planting herbs for pollinators (plus a recipe!)

Save the date for next year’s Pollinator Week plant sale, where you can purchase a pollinator-friendly plant, many of which we have grown from seed!

Pollinator Week BINGO!

Every year, a week in June is dedicated to celebrating pollinators. All week long TPI will be posting pollinator-related videos, blog posts, etc. PLUS, you can play BINGO for a chance to win a prize!

To play Pollinator Week BINGO, which features flower-visiting insects you can find in the Northeastern USA this time of year, download and print the Bingo card (below) or screen shot the image on your phone. Take your card/phone outside and if you find the correct insect, mark it off on your printed card with a pen/pencil or with your phone’s photo annotation option.

If you get BINGO! (five in a row, vertical, horizontal, or diagonal, TPI logo is a free space), send a photo of your annotated card to tuftspollinators@gmail.com or tweet a photo and tag @PollinateTufts by 11:59 pm on Friday, June 26. Each completed BINGO! card will be entered in a drawing to win TPI swag and a voucher for a free pollinator-friendly plant at next spring’s TPI plant sale! Limit one entry per person.

For help identifying the insects you observe, download our identification guides or reach out to us with photos via email or Twitter!


Stay tuned for more #PollinatorWeek fun!

Happy World Bee Day!

Did you know there are 20,000 species of bees in the world? And that 4,000 of those species are native to North America? In celebration of World Bee Day, we highlight some of the bees TPI members have studied across the United States and in Costa Rica.

Common eastern bumble bees (Bombus impatiens) are important pollinators of greenhouse tomatoes, blueberries, and pumpkins.
Photo: Genevieve Pugesek

Though the common eastern bumble bee is one of the more common bee species in the Northeastern US (as its name suggests), we still have a lot to learn! With help from Tufts undergrad and grad students, I am working to understand where queen eastern bumble beeshibernate. As it turns out, unlike most other species of bumble bees, these queen bees hibernate right next to the nest they were born in. So, if you are creating habitat for nesting bumble bees, you might be creating habitat for hibernating queens too! If you visit our pollinator gardens (while practicing safe social distancing) this spring, you’re likely to see these fuzzy bumble bees flying around.

Genevieve Pugesek, PhD Student, Tufts University

Yellow-faced bumble bees (Bombus vosnesenskii) pollinate many wild plants as well as crop plants such as tomatoes and berries.
Photos: Elizabeth Crone, Rachael Bonoan

For the past 5 years, I worked on this species in collaboration with Neal Williams (Assoc. Professor, University of California), Rosemary Malfi (now post-doc, UMass Amherst) and Natalie Kerr (now post-doc, Duke University).  We found that yellow-faced bumble bee colonies especially need resources to forage on during early stages of colony development.  In the same way that early childhood nutrition affects human health throughout their lives, early spring flowers help these bumble bee colonies grow!  Spring resources allow colonies to produce larger worker bees that are better at foraging for resources, leading to higher resource return even after the spring pulse of flowers ends.  The importance of spring resources has implications for bee conservation because native plants in California mostly flower during the wet spring, whereas irrigated crop plants mostly flower in the dry summer.  If we want yellow-faced bumble bees to be around to pollinate summer crops, we need to keep spring flowers on the landscape.

Elizabeth Crone, Professor, Tufts University

Hibiscus bees (Ptilothrix bombiformis) pollinate plants in the Malvaceae family including cotton, hibiscus, and saltmarsh mallow.
Photo: Judy Gallagher, Flickr

I spent a summer surveying native bees along Virginia’s Eastern Shore and studying the effects of sea level rise on native bee communities. The hibiscus bee was the most common species found on farms, meadows, and salt marshes along the coast. On steamy summer mornings, this bumble bee doppelganger could be found buzzing around marsh hibiscus or visiting blooming cotton fields.

Jessie Thuma, PhD Student, Tufts University

Blueberry cellophane bees (Colletes validus) are specialists that pollinate blueberries.
Photo: Max McCarthy

Different bee species have different diets; some collect pollen from a wide variety of flowers (generalists) while other species forage on the flowers of only a few types of plants (specialists). I sampled pollen from blueberry cellophane bees to understand what types of floral resources this species uses throughout its flight season in May and June. After identifying pollen samples under a microscope, I found that, true to their name, these bees rarely collect pollen from plants other than blueberry bushes.

Max McCarthy, Undergraduate, Tufts University

Honey bees (Apis mellifera) are generalist forages known to pollinate our crops.
Photo: Rachael Bonoan

I study how honey bees regulate in-hive temperatures in order to protect temperature-sensitive eggs and larvae. In order to develop properly, honey bee larvae must be kept at 32 – 36 °C (about 89 – 96°F). With the help of NSF REU students, I found that when an area of a honey bee hive is exposed to heat stress, the queen stops laying eggs in the “too hot” area. Instead of raising young in this hot spot, worker bees store nectar (food!).

Isaac Weinberg, PhD Student, Tufts University

Squash bees (Peponapis pruinosa) are known for pollinating…you guessed it…squash.
Photo: USDA ARS, Wikimedia Commons

As a lead field technician at UW-Madison, I worked with a team to investigate how the diversity and abundance of floral vegetation on small-scale organic farms impacted bee communities and crop flower visitation. We were interested in cucurbit (e.g. cucumbers, watermelons, squashes) pollination, as these crops rely solely on insect pollination. While I was fortunate to study a diversity of bees in this project, my heart was captured by Peponapis as the males scurried around giant squash flowers. Fun fact: When the squash flowers close mid-day, squash bee males nestle up and sleep in the protection of the closed flower until they reopen the following day. 

Sylvie Finn, Incoming PhD Student, Tufts University

Yarrow’s fork-tongue bee (Caupolicana yarrowi) pollinates wild nightshade, and is parasitized by a cuckoo beeTriepeolus grandis.
Photo: Nick Dorian

Yarrow’s fork-tongue is a large, ground-nesting solitary bee that inhabits high deserts of southwestern US and Mexico. Unlike most bees, it cannot be found during the day, but instead is active pre-dawn and post-dusk. In August 2018, several participants of the 2018 Bee Course and I woke up extra early to find nesting females. We found three nests and carefully excavated the long, sinuous tunnels to claim our prize: brood cells. Most cells contained just a Yarrow’s fork-tongue larva feeding on a slurry of pollen and nectar. In one cell, however, we also found an intruder: the larva of a cuckoo bee (Triepeolus grandis). With formidable mandibles, the cuckoo bee larva kills the host and develops on the stolen provisions. This may sound malicious, but it’s simply how the cuckoo bee lives. About 15% of all bees are cuckoos, meaning these pollinators would cease to exist without their host bees!

Nick Dorian, PhD Student, Tufts University

Stingless bees (Trigona spp.) are generalist tropical pollinators that forage on flowers and meat.
Photo: Rachael Bonoan

This past January, some TPI members traveled to Costa Rica with Tufts University’s Tropical Ecology and Conservation course. There, Nick and I studied mineral preferences of facultative “vulture bees,” stingless bees that forage at meat as well as flowers. We identified five species of bees (including Trigona silvestriana, pictured above) foraging at our baits and found that compared with unaltered baits (i.e. raw chicken), stingless bees tended to avoid baits soaked in calcium and potassium. In contrast, bees visited sodium-soaked baits just as often as unaltered baits. This suggests that like many herbivores, meat-foraging bees are likely limited by sodium and will suck up the salt wherever they can find it!

Rachael Bonoan, post-doctoral researcher, Tufts University

Orchid bees (Euglossa spp.) are known for pollinating orchids in the tropics.
Photo: Atticus Murphy

Can you see the thin yellow object on the back of this shiny green orchid bee? This is a pollinium, a packet of pollen grains, likely from an orchid. Male orchid bees forage at flowers for nectar, which provides nutritional energy, and floral scents, which are used to court females. In Costa Rica, my research partner and I captured orchid bees and used tiny glass tubes to suck up the contents of the crop, where collected nectar is stored. We measured sugar content of the bee-collected nectar and found that bees caught in human-dominated open spaces had more dilute crop contents than those caught in the forest. This may be because the open spaces were sunnier and hotter, driving the bees to drink more water.

Atticus Murphy, PhD Student, Tufts University

Interested in learning more about the bees in your backyard? Check out our insect identification guides! For even more bees, our favorite books are The Bees in your Backyard by Joseph S. Wilson and Olivia Messinger Carrill and Bees: An Identification and Native Plant Forage Guide by Heather Holm.
TPI members at work!

Tufts University Medford-Somerville is now a Bee Campus USA!

TPI is excited to announce that we have reached our goal: Tufts University Medford-Somerville has become the first urban educational institution in Massachusetts to be certified as an affiliate of the Bee Campus USA program! Bee Campus USA is designed to marshal the strengths of educational campuses for the benefit of pollinators via the creation of pollinator habitat, service-learning projects, and educational programming.

Funded by the Tufts Green Fund in 2019, we created TPI as an ecological, educational, and collaborative effort to bolster pollinator health and promote community awareness on the Medford-Somerville campus. If you’ve been keeping up with our blog, you may have heard that we have planted three pollinator-friendly gardens on the Medford-Somerville campus, which provide forage for pollinators from May through October. In just one year, we reached over 2,000 people via public-facing events such as Tufts Community Day, workshops, lectures, and the recent screening of The Pollinators. We have also advised pollinator conservation efforts at other universities in the Boston Area (e.g. Lesley University, Northeastern University) as well as other Tufts campuses. In this year’s round of Green Fund projects, the Sustainability Committee at the School of Museum of Fine Arts (SMFA) at Tufts was awarded funds to create pollinator-friendly gardens on their Boston campus. We cannot wait to help the SMFA Sustainability Committee create signage and select plants for their gardens!

TPI members with Peter Nelson, director of The Pollinators, following our Pollinator Fair (complete with honey tasting!) and film screening.
Nick Dorian teaches young community members about which crops are pollinated by bees at Tufts Community Day.

Elizabeth Crone, Professor of Biology and TPI member, is excited about the opportunities for student research and service-learning with the Medford-Somerville gardens: “In the same way that National Parks were a new idea in the early 1900’s, urban pollinator gardens are the next frontier for conserving insect diversity in the 21st century.” Our on-campus pollinator gardens have already been integrated into a Tufts undergraduate-level course, “Insect Pollinators and Real-world Science,” where students visited a garden and created their own pollinator-specific planting guides. We are now working to create undergraduate research projects to survey pollinator biodiversity and the food resources (nectar and pollen) the gardens provide, and recently created an iNaturalist Project for community scientists interested in contributing biodiversity data.

Bee City USA and Bee Campus USA are initiatives of the Xerces Society for Invertebrate Conservation, a nonprofit organization based in Portland, Oregon, with offices across the country. Bee City USA’s mission is to galvanize communities and campuses to sustain pollinators by providing them with healthy habitat, rich in a variety of native plants, i.e. food resources for pollinators. Animal pollinators such as bumble bees, sweat bees, mason bees, honey bees, butterflies, moths, beetles, flies, hummingbirds and many others are responsible for the reproduction of almost ninety percent of the world’s flowering plant species. In fact, one in every three bites of food we consume is thanks to animal pollinators, specifically insects!

“The program aspires to make people more PC—pollinator conscious, that is,” said Scott Hoffman Black, Xerces’ executive director. “If lots of individuals and communities begin planting native, pesticide-free flowering trees, shrubs and perennials, it will help to sustain many, many species of pollinators.”

We would like to thank to the Tufts Green Fund for funding this project, the Garden Club of America for their support, and our current and past members for helping us toward our goal! As a certified Bee Campus USA, we will continue doing outreach, education, and research, and spreading the pollinator love!

TPI supports pollinators by cultivating native plants on the Medford-Somerville campus. Here, a monarch collects nectar from blazing star.

Lazy lawnmowers and landscape mullets

By Atticus Murphy

Maybe you’re the type of person who’s interested in nature but don’t know you can help. You live in a city or a suburb, with not much space and just a typical grassy lawn covering what space you have. Maybe you’ve also recently learned that insect pollinators like bees are crucial for our ecosystems but may be experiencing significant declines caused by habitat loss due to humans. What can you do to help, without breaking the bank or spending too much of your time on gardening?

 A lawn with a more and less frequently mowed portion on left and right respectively, showing the diversity of flowers that can emerge when given time to grow (Photo: Sue Pranskus). 

If this sounds like you, there’s a surprisingly simple option available to you: do less! Mowing grass lawns frequently (more than twice a month) is a good way to keep the grass cropped low and cut down on weeds. But this low, flowerless grass lawn is essentially a food desert for bees and other pollinators. Happily, studies have shown that if you simply mow a bit less, your once barren yard can become a buffet for bees in just a few short weeks. Simply shifting towards cutting your lawn every two or three weeks instead of once a week can greatly increase the number of bees and other pollinators that are able to forage there, as quick-blooming “weedy” flowers sprout up from the soil. Instead of treating weeds like unwanted invaders, to help save our native bee populations, treat them like welcomed guests! They’ll beautify your lawn for a few days at a time all throughout the growing season and they’ll do it for free. All it takes it giving them a bit more time between mowing to put up their flowers. 

If you enjoy using your lawn for outdoor activities or are required to maintain it at a certain length by local authorities, reducing your mowing frequency as much as you can within these limits is still a great way to help pollinators by giving flowers more of a chance to bloom before cutting them. Remember, this “lazy lawnmower” strategy for helping pollinators does not require drastic lifestyle changes: instead, it might be totally compatible with whatever uses you get out of your lawn now. Green grass can remain on your property for sitting, lying, and playing, and you can see significant numbers of new flowers all while still keeping your lawn looking well-kempt. If you’re concerned about appearances and don’t want to give over the front lawn to being taller, then consider only letting your back lawn grow out a little. Scientists have nicknamed this practice the “landscape mullet” because like the famous haircut, it’s longer at the back. Because pollinators are able to move around to locate flowers, they will be served just as well by a back lawn with flowers as they would a front lawn.

A monarch butterfly feeding on a mustard flower (family Brassicaceae) sprouting from a grassy lawn (Photo: Rachael Bonoan).

What types of flowers will spontaneously recruit in your lawn? It’s hard to say, and that’s part of the fun! In Massachusetts you might expect to see pollinator-friendly flowers like dandelions (Taraxacum species), clovers (Trifolium species), butter-and-eggs (Linaria vulgaris) and other quick-blooming, low-growing species, like the mustard pictured above. Many of these species may not be native to the U.S., but they are nevertheless great sources of nutrition for native pollinator species. So if you’re interested in helping pollinators but don’t want to make the leap into pollinator-friendly gardening just yet, getting a little lazy with lawn management and welcoming some weeds into your life is a great first step towards making your property a refuge for native insect pollinators. 

Turning up the heat: strange (and stinky) skunk cabbage

It may be hard to imagine finding flowers and pollinators in February, but the first flowers of the spring can already be seen blooming all across New England. Poking up from the frozen ground of swamps and stream banks, skunk cabbage (Symplocarpus foetidus) doesn’t exactly look like your average flower. It produces multiple small flowers on a central spike, or spadix, surrounded by a purplish hood known as a spathe. Few other flowers in northeastern North America share this odd floral structure – a characteristic of plants in the largely tropical Arum family, which includes popular houseplants like Spathiphyllum (peace lily), Philodendron, and Monstera.

Skunk cabbage flowering along a small stream in Massachusetts in late February. Skunk cabbage spathes are easy to overlook, but can be quite common in wetlands in late winter and early spring.

Aside from its bizarre appearance, skunk cabbage stands out from other native New England plants with another unique feature: its flowers have the ability to produce significant amounts of heat! Fueled by energy stored in the plant’s modified underground stem (called a rhizome), skunk cabbage can maintain temperatures of over 50 degrees within the spathe even as external air temperatures drop below freezing. Skunk cabbage flowers produce varying amounts of heat depending on environmental conditions as well as their age. Like some other related plants in the Arum family, skunk cabbage flowers are all female when the spathe first opens. These later become pollen-producing male flowers, with flowers at the top of the spadix transitioning first. Heat production peaks during the female phase, declining as the flowers age and begin to produce pollen.

Skunk cabbage spathe. This structure surrounds the plant’s central flower spike. Its mottled purple color may function to attract carrion-feeding flies that could act as pollinators.

Why does skunk cabbage produce heat? Despite several studies of this phenomenon, the answer is unclear. Production of heat may be necessary to allow skunk cabbage to grow and flower in a rather inhospitable environment, preventing the buildup of snow and ice around the spathe. By flowering well before most other plants, skunk cabbage may be able to take advantage of any insects that are active at this time of year, with heating performing the additional function of attracting insect pollinators. The purplish color of skunk cabbage spathes, in addition to their unpleasant smell, suggests that they may be pollinated by flies. Other primarily fly-pollinated plants share similar traits, tricking flies into visiting their flowers when searching for sites to lay eggs. By heating its spathes, skunk cabbage could provide an extra incentive for these early-season insects to visit its flowers.

Although scavenging flies hardly seem like likely pollinators, they can be quite important to the pollination success of some groups of plants that specialize in attracting them.

While flies have been documented at skunk cabbage flowers, frequency of successful pollination events seems to be quite low. Interestingly, some of the insects most often seen at skunk cabbage flowers are honey bees, which visit male skunk cabbage flowers as an early-spring source of pollen. However, it’s unlikely that honey bees act as effective pollinators, since they tend not to visit skunk cabbage’s nectarless female flowers and may not even make contact with the spadix itself, instead collecting pollen that has fallen to the base of the spathe.

Skunk cabbage provides an excellent example of just how much remains unknown about the ecology of some of our most ubiquitous (and fascinating!) native plant species. As you walk through the woods in late winter and early spring, keep an eye out for this strange plant in any area with wet soil and appreciate the incredible adaptations skunk cabbage has evolved that allow it to thrive at a time when few other flowers dare to bloom.

PC: Max McCarthy

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!

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!

The butterflies who are raised by ants

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.