Help TPI find bumble bee colonies!

While you’ve been hunkered down at home, have you seen any bumble bees in your urban yard? Maybe you’ve even seen a bumble bee nest! We want your help in scouting out the bumble bee nests of the urban greater Boston area.

TPI scientists have been hard at work trying to learn about the nesting ecology of bumble bees (Bombus spp). Bumble bee nests are the focal point of reproduction. In early spring, the queen emerges and forages alone for pollen and nectar. Then, she produces workers which take on foraging tasks, and the colony grows exponentially. Late in the season, as the colony begins to senesce, males and new queens are produced. After mating, males die and queens overwinter underground to start the cycle over.

Bumble bee reproduction cycle
Bumble bee life cycle. Image credit: Jeremy Hemberger

We have learned a great deal about bumble bee nesting in natural areas, but now it’s time to take that work into the city. Preliminary results already suggest that bumble bee reproductive ecology may differ between natural and urban environments, and we want to explore this further. Bumble bee nests can be difficult to find, but that’s where YOU come in.

Do you think you’ve seen a bumble bee nest? We want to see it! Bumble bees are cavity nesters, meaning they nest in small openings, such as crevices in rock walls beneath garden sheds. If you see frequent traffic of worker bumble bees (~1 bee/minute) to and from a single location, chances are you found a colony! 

Bumble bees nesting in an old bird house. Image credit: Kstevens01, Flickr

If you think you have a bumble bee nest in your yard, or know of one in the greater Boston area (within 15 miles of the Tufts Medford-Somerville campus), take a photo and get in touch with us by filling out this survey.

Thank you in advance and we look forward to hearing from you!

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!

Let herbs flower in your quarantine garden

As the heat of summer approaches, your quarantine garden will rely on insect pollinators to produce its bounty. Tomatoes. Cucumbers. Heaps of zucchini. This free ecosystem service—pollination—is often taken for granted, but it wouldn’t be possible without the help of insects: bees, butterflies, hover flies, beetles, and wasps.

To support these insect pollinators, you don’t need another garden. Simply let you herbs flower.

Herbs are a group of plants that have at least one organ (leaves, stems roots, flowers) that is tasty or medicinal. Leaves and stems get all the attention, while flowers often get overlooked, clipped away with the dead leaves and added to the compost. Not only are herb flowers almost always edible, but they also offer a veritable feast—nectar and pollen—to pollinators.

We most often eat the leaves and stems of herbs, like chives, thyme, and sage, but pollinators feast on the nectar and pollen from the flowers. PC: Timothy Vollmer, Flickr

Case in point: chive flowers feed sweat bees and carpenter bees after a long winter; the inverted flowering parasols of dill are a favorite of beneficial wasps and hover flies; and you’d be hard-pressed to find a flowering blade of lavender without a bumble bee. Moreover, flowering herbs teach a valuable lesson in pollinator gardening 101. Diversity begets diversity. To support all the pollinators that make your garden productive, plant diverse herbs.

Bumble bees are always attracted to the nectar-laden flowers of oregano. PC: Nick Dorian

It’s not hard to get started. Compared to pollinator-friendly native plants*, herbs are easy to procure. Seedlings are available for purchase at garden centers and many grocery stores in spring and summer.  

Herbs are also conducive to being grown in containers, making pollinator gardening possible anywhere, even on balconies or in window boxes. Herbs are forgiving to grow (sometimes downright invasive, another reason to use a container) and only require regular watering and some direct sun. And best of all? The strong flavor of the leaves that we enjoy in our cooking is despised by rabbits and deer.

Herbs are particularly conducive to container gardening. Here, the gardener has flanked orange tomatoes (center) with herbs. By letting their herbs flower, they will support bees that pollinate tomatoes. PC: greckor, Flickr

When picking out herbs for your garden, my recommendation may seem counter-intuitive: grow what you like to eat. Gardening for pollinators can be more involved, but it doesn’t have to be. All flowering herbs support pollinators. By selecting particular combinations of herbs to grow, however, you can maximize the benefits of your quarantine garden for pollinators. Here are four tips:

  1. Combine herbs that vary in flower shape (e.g., dill, lavender, borage, chamomile).
  2. Combine herbs that vary in fragrance (e.g, cilantro, basil, rosemary, lemon balm).
  3. Combine herbs that vary in size (e.g., thyme, chives, nasturtium, fennel).
  4. Combine herbs that flower in succession, from spring (e.g., chives, sage, rosemary) to early-summer (e.g. thyme, lavender) to late-summer (e.g., basil, oregano).

Next, put your herbs in the ground or in a pot with plenty of room to grow (6-8” between plants). Water them well at first, then a few times per week or whenever the leaves begin to wilt. If you already have herbs in your garden, even better! You’re ahead of the game.

In New England, thyme flowers in early summer and feeds many pollinators. It’s perennial, meaning it will feed pollinators year after year. PC: Nick Dorian

Harvest leaves and stems throughout the season (morning or early evening is best!). Use them fresh or dry them for later. A few of my favorite things to make with herbs: mint-watermelon cooler,  gnocchi with brown butter-sage sauce, and pesto potato salad.** With leftover pesto, I make pesto ice cubes to enjoy garden freshness all winter long.   

At some point during the growing season, your herbs will want to flower. The flowering time of the herb depends on its life cycle. For perennial herbs that come back each year, such as chives or sage, the plant will flower at a predictable time each year alongside your harvest. For annual herbs that die at the end of the growing season, such as basil or cilantro, the plant will flower at the end of summer or if it gets too cramped in its container. In both cases, the leaves and stems are still edible while the plant is flowering, but they will be tougher and less sweet than before.***

Honey bees love flowering lavender!

Letting your herbs flower is a simple, intentional act that sets in motion the dinnertime rush. Take time to notice your guests. Notice how bees push and reach over each other to get food on their plates, family style. How hover flies wait back for the perfect moment to land, so they can eat without being disturbed. How butterflies sip nectar, polite and upright, as if dining at a fine restaurant. Take pride that you’ve put food on their table, just as they have on yours.

*Flowering herbs are non-native, introduced by colonists. That means our native pollinators don’t share an evolutionary history with herbs and, therefore, don’t benefit as much from herbs as they do from native plants. If you’re interested in adding native plants to your garden, check out our handout for recommendations on what to plant.

**Pesto potato salad

  • 2 cups quartered baby potatoes
  • 1T paprika
  • 2T chopped rosemary
  • 1c green beans, cleaned and cut into 1in pieces
  • 4 roma tomatoes, halved
  • 2c fresh basil, loosely packed
  • 2T sunflower seeds
  • juice of half a lemon
  • 1/4c grated parmagiano regiano
  • 1/2c extra virgin olive oil + 2T extra for potatoes
  • 1 large or 2 small cloves garlic
  • salt and pepper to taste

Preheat oven to 400˚F. Toss quartered potatoes in olive oil, salt, pepper, paprika, and chopped rosemary and roast in oven for 35-40 minutes. Meanwhile, blanch green beans in boiling water for 60 seconds, then shock immediately in ice water. Set aside. If possible, grill tomato halves for 8 minutes, until charred and cooked. If not, place in the oven with potatoes for the final 10 minutes of roasting. Dice tomatoes and toss the body of the salad to mix. Dress with pesto (see below). Enjoy!

Earlier that same day (or while potatoes are roasting), prepare pesto. Process together basil, sunflower seeds, lemon juice, garlic, cheese, and s&p, slowly drizzling olive oil into the blender to emulsify and incorporate. Adjust seasoning to taste. 

Pesto potato salad features basil.

***Nick’s tip: If you want to delay the flowering of your herbs, perennial or annual, clip off incipient flower buds. Do this when the buds are small.

Which pollinator are you?

Written by: Sylvie Finn, one of our newest TPI members!

It’s National Pollinator Week, so in an effort to learn about our diverse pollinators, take this quick quiz to see which pollinator is in your personality!

Directions: This is an old school keep-track-yourself type of quiz. Think personality quiz in a tween magazine. Grab a piece of scrap paper, keep track of how many A’s, B’s, C’s, etc you have, and at the end you will be able to discover something fabulous about yourself.

1. Imagine you step into your dream house. You look around and see:

A. Ornate geometric patterns
B. Sophisticated plaster work all around
C. The house you’re sitting in right now!
D. This is a hard question…I’d rather have two totally different and exciting homes
E. As long as there’s a stacked pantry, I’m happy!
F. Something I build myself to my liking

2. Your friends would describe you as:

A. Hardworking
B. Friendly
C. High strung
D. A social butterfly
E. Loyal
F. Hyper

3. On a Saturday night, you can be found:

A. Out on the town with “the girls”
B. Working in your basement
C. At a dive bar with your buddies hovering around the peanut and pretzel bowls at the bar
D. Getting your beauty rest
E. Cuddled up with a good book
F. Indulging in your sweet tooth

4. Your personal style is:

A. Whatever your friends are wearing
B. Stripes!
C. All black every day
D. Bold color choices
E. Give me that fuzzy sweater
F. Metallics anyone?

5. Your favorite color is:

A. Yellow
B. Blue
C. White
D. Pink
E. Ultraviolet
F. Red

6. You get to the park and someone is sitting on your favorite bench, you:

A. Take a seat, there’s room for two
B. Decide that going to the park was a horrible idea
C. Linger in front of the bench until the person sitting there becomes uncomfortable and leaves
D. Go to another bench, there are plenty of benches to go around
E. What person? I see a bench, I sit
F. I don’t have this problem, no one likes the kinds of benches I do

7. Your dream vacation:

A. Take me to a new city! I love a buzzing metropolis
B. Exploring a cave with your pals
C. An all-inclusive resort just for the all-you-can-eat buffet
D. Mountains of Mexico, please and thank you
E. Stay-cation works for me, as long as there are snacks
F. Take me anywhere ~TroPiCaL~

8. For your birthday this year, you want:

A. A big party with all of my of friends and acquaintances
B. A small party with only my closest friends
C. To be left alone
D. To fly in the sky! Paragliding? Skydiving?
E. To make sure those around me are well fed
F. To go on an adventure somewhere new

Time to find out which pollinator you are…

MOSTLY A’s: Honey bee (Apis mellifera)

You are the “gold” standard for bees. Known for your incredible social intelligence and honey making skills, you are very hardworking and constantly referenced. You’re a total feminist, loving to live in female-dominated society.

Photo: Rachael E. Bonoan, Flickr
MOSTLY B’s: Cellophane bee (Colletes spp.)

You are an aesthetic architect. You are literally named after the materials you build with and are fashionable in your stripes and fluff. You like your alone time, but enjoy sharing experiences with friends when the time is right.

Photo: Team Colletes, Flickr
MOSTLY C’s: Hover fly (e.g. Eristalis transversa)

You are one of the lesser known pollinators and you like it that way. Your fast paced lifestyle keeps others on edge and you always stay unconventional.

flower fly, hover fly
Photo: Team Colletes, Flickr
MOSTLY D’s: Monarch butterfly (Danaus plexippus)

You are the poster child of all butterflies. Like a monarch, you are elegant and have very specific taste. You also are a total travel junky and love to go to new places beyond what your imagination can hold.

monarch butterfly
Photo: Nick Dorian
MOSTLY E’s: Bumble bee (Bombus spp.)

You are everyone’s best friend, smart and oh so sweet. You know how to cuddle up with a good book, but when you think theres some good food somewhere, you can zoom there quite quickly.

Photo: Team Colletes, Flickr
MOSTLY F’s: Ruby throated humming bird (Archilochus colubris)

You are many people’s favorite birds and a very special pollinator. While there are hundreds of species of humming birds in the tropics, you are the only one to grace us here in the North East. If people can catch a glimpse of you, you always dazzle them.

Photo: Michael Janke, Flickr

Let’s celebrate pollinators!

How to bake pumpkin (Cucurbita pepo) empanadas

When I was growing up, my mom often bought pumpkin empanadas from El Aguila bakery in Fremont, Ohio. Let me tell you, there isn’t anything better with a hot cup of coffee.

As a kid, I never realized the important role pollinators play in creating these special treats. While many crops are pollinated by the wind (wheat, corn, rice), many fruits and vegetables are pollinated by insects. In fact, two important ingredients in my favorite empanada recipe benefit from animal pollinators. 

Without insect pollinators, particularly bees, there would be no pumpkin, the main ingredient of the empanada filling. Pumpkin vines produce male and female flowers – this means that some flowers produce pollen, while other flowers bear fruits. Pollen from the anthers of male flowers must be deposited on the stigmas of female flowers for the vine produce fruit. Since pumpkin pollen grains are very heavy, pumpkin flowers cannot be pollinated by the wind. Instead, pollen grains must hitch a ride on a bee.

One of the cutest – and most important – pollinators of pumpkin are squash bees (Eucera pruinosa). Squash bees are solitary, ground nesting bees: a single female digs a nest for her offspring in the soil. Found in both the United States and Mexico, squash bees collect pollen exclusively from plants in the gourd family (genus Cucurbita), including pumpkin, zucchini, and summer squash. These little bees are super effective pollinators of squash plants, transferring up to 4 times as much pollen between flowers as honeybees.

Photo Credit: Elsa Youngsteadt

Oranges, used to flavor the filling of empanadas, are another ingredient which can benefit from insect pollinators. Unlike pumpkin flowers, orange flowers are hermaphroditic: flowers can produce pollen and bear fruits. Orange flowers can be pollinated without help of insects if pollen from anthers is shed directly onto the stigma of the flower. However, orange flowers still are better off with bees than without. Without the help of an insect, flowers may be insufficiently pollinated, and will produce smaller and more acidic fruits. Sweet orange production is 35% higher for flowers visited by pollinating insects (like honeybees) compared to unvisited flowers.

Photo Credit: Kathy Keatley Garvey

In honor of National Pollinator Week, I wanted to share with you one of my favorite recipes for pumpkin empanadas, modified from a recipe originally published by La Piña en La Cocina.

Pumpkin (Cucurbita pepo) Empanadas


For the Pastry:

  • 2.5 cups all-purpose flour
  • 1/4 cup cold butter
  • 1/4 cup brown sugar
  • 1/2 tablespoon active dry yeast
  • 1 large egg at room temperature, lightly beaten
  • 1/2 tablespoon cinnamon
  • 2/3 cups warm milk (110 degrees F)

For the filling:

  • 16 oz canned roasted and pureed pumpkin
  • 1/3 cup brown sugar
  • 6 star anise pods
  • 1 cup of water
  • 1 cinnamon stick
  • 1 tablespoon orange juice concentrate
  • Zest from one orange

For assembly

  • 1/4 cup milk
  • 1 lightly beaten egg white


To prepare the pasty, sift flour into a large mixing bowl. Cut in butter, then cut in sugar, cinnamon, and yeast. Add the egg, and slowly incorporate milk until a dough forms. Knead for 6-8 minutes. The dough should be fairly sticky. If it is too dry, add more milk, and if it is too wet, add flour. Let rise about 2 hours.

To prepare the filling, boil star anise and the cinnamon stick in about 1 cup of water for about 10 minutes (or until about half of the water is evaporated). Add pumpkin, sugar, and juice concentrate to ¼ cup of this liquid, and cook until thickened, about 10-20 minutes. Let the filling cool in the fridge.

After the dough has risen, preheat the oven to 375 degrees F. Punch down the dough and divide into 1.5 oz balls. Roll out each ball until it is 4 inches in diameter. Place two tablespoons of filling in the center of the dough.

Brush the edges of the dough with egg white and fold the over dough and press out any air. Crimp the edges using a fork, or pinch to seal. Place the filled pastry on a greased backing tray. Repeat until all of the dough has been used. Once the pastries are all shaped, bush tops with milk. Bake for 20-25 minutes, until the pastry becomes a dark, golden brown. Makes 10-12 empanadas (which are best eaten within a day or two).

Enjoy! I hope you all have a very happy National Pollinator Week!


Canto-Aguilar, M. A., & Parra-Tabla V. (2000). Importance of conserving alternative pollinators: assessing the pollination efficiency of the squash bee, Peponapis limitaris in Cucurbita moschata (Cucurbitaceae). Journal of Insect Conservation 4: 203–210.

Malerbo-Souza, D. T., Nogueira-Couto, R. H., & Couto, L. A. (2004). Honey bee attractants and pollination in sweet orange, Citrus sinensis (L.) Osbeck, var. Pera-Rio. Journal of Venomous Animals and Toxins including Tropical Diseases 10(2): 144–153.

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 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!

Stop calling it the “murder hornet”

Recently, news outlets have been spreading fear of the “murder hornet” invading the United States. To be clear, the “murder hornet”, actually known as the Asian giant hornet (Vespa mandarinia), does not pose a direct threat to humans. While a sting from this hornet may hurt, Asian giant hornets are generally not aggressive unless provoked. Stinging is a form of protection, and like any stinging insect, the Asian giant hornet is not out to sting you.

Instead, Asian giant hornets are after much smaller prey: honey bees.  Asian giant hornets are carnivores, meaning they feed insects to their developing young. A honey bee colony, with tens of thousands of bees, is a great place to collect protein-rich food. In one foraging trip, one Asian giant hornet can kill up to 40 honey bees! As you might imagine, a whole colony of these hornets could be fatal to a honey bee colony.

In their native range of eastern and southeastern Asia, Asian giant hornets have been predating on Asian honey bees (Apis cerana) for a long time. In response, Asian honey bees have adapted a defense strategy: heat. When the hornet invader is detected, worker bees sound the alarm by shaking their abdomens. Then, in a swift, coordinated response, hundreds of honey bees swarm the hornet and contract their flight muscles, generating intense heat. Together, the worker bees heat the hornet to about 117 °F, killing the intruder. As it happens, the hornet can only withstand temperatures up to 115 °F, while Asian honey bee workers can withstand temperatures up to 118 °F. Evolution is a beautiful thing.

Sterile female worker bees perform all the tasks in the colony, including taking care of the queen (white paint mark) and defending the hive from intruders.

But, the Western honey bees (Apis mellifera) that are managed in North America have not evolved with this predator and are not as well equipped to defend themselves. This is why we need to be worried about the Asian giant hornet. Managed honey bees provide valuable economic and ecosystem services such as beekeeper livelihoods and agricultural pollination—the Asian giant hornet jeopardizes the security of these services.

While this is certainly cause for concern, panic is unwarranted. Since August 2019, the Asian giant hornet has been spotted just three times in Washington State and three times in British Columbia. Following a recent report of a honey bee colony death that resembled the work of this hornet in Washington (although it is unconfirmed), Washington State Department of Agriculture entomologists are on the hunt to stop the hornet before it spreads.

Fortunately, Asian giant hornets have not been spotted on the east coast, and it would likely take a while for them to get here. As with any introduced species, however, attempts should be made to spot the hornets early on. If you think you have seen an Asian giant hornet in Massachusetts (which is currently highly unlikely) you can report a sighting to the Massachusetts Introduced Pests Outreach Project.

Identifying Asian giant hornets: The European hornet (Vespa crabro) is often confused for the Asian giant hornet. There are three main differences between these hornets:

  1. Size The Asian giant hornet is slightly bigger than the European hornet (photos not to scale, enlarged for detail).
  2. Stripes The Asian giant hornet has regular black-orange stripes along its abdomen; the European hornet has irregular brown-yellow stripes.
  3. Head The Asian giant hornet has an orange head; the European hornet has a golden yellow head.
LEFT: Asian giant hornet, Washington State Department of Agriculture, Flickr
RIGHT: European hornet, Chris Moody, Flickr

To learn more about the Asian giant hornet, please read this USDA report instead of news articles. To learn more about how you can help mitigate the establishment of introduced species in general, check out these resources:

Return of the honey bees

Isaac Weinberg

To watch my honey bee spring inspection click here!

Spring has sprung, and the bees and butterflies have begun their return to Medford. If you’re like me, you may have wondered why insect pollinators were gone in the first place. Cold temperatures and lack of flowering plants make New England winters an inhospitable place for insects, yet year after year they return. Different species use different strategies to get through the winter months. Monarch butterflies dodge the cold by migrating south for the winter. Bumble bee queens sleep through the winter in subterranean burrows. Other insects lay eggs in fall that remain dormant in winter and hatch in spring.

Honey bees are unique in that they are the only insect pollinator that is awake and active throughout the entire winter. They are able to do this because of their massive colony size of up to 50,000 bees. Honey bees bunch up in their hive like emperor penguins and spend all winter shivering by flexing their wing muscles to keep their hive warm. Even in the coldest months of winter, honey bees can keep the temperature of their colony above 90 degrees Fahrenheit! In order to have energy to shiver all winter, honey bees hoard pounds of honey and pollen in the summer and fall which they eat for energy over the course of winter.

a Varroa mite (visible in red) feeds on the fat body of a developing bee.

Recently, overwintering deaths of managed honey bee colonies in the US has been incredibly high, with almost 40% of colonies dying each winter. Over the winter it is very difficult for beekeepers to directly help colonies, since opening a hive and exposing it to the cold would be incredibly damaging. Because of this, many beekeepers to take an active hand in helping their bees in the early spring. The first cool days in spring are very dangerous. They have likely consumed all their food stores and, with few flowers yet blooming, there may be no way for them to restock. Spring is also when there are is an explosive increase in populations of Varroa destructor, a parasitic mite that latches on to honey bees and eats their fat bodies. In the spring it is often critical for beekeepers to supplement the nutrition of their colonies, and keep the mite population under control in order to have strong healthy hives during the year.

Honey bees get most of their nutrients from different flower products, they collect sugar rich nectar to make honey which adult bees use as their main source of energy, and protein rich pollen which is fed to larvae to help them grow. In order to help supplement the diets of bees, beekeepers can feed their colonies sugar solution, and synthetic pollen patties. One type of pollen patty is made using bee collected pollen and mixing it with a 1:1 sucrose:water solution until it has a clay like consistency. In the absence of pollen, other supplements like yeast, protein powder, and eggs can be mixed with sugar water to create patties. Patties can then be made available to the bees by simply placing them in the center of the beehive.

A pollen patty wrapped in freezer paper and placed in the center of a honey bee hive.

Next, many beekeepers treat for the mite Varroa destructor. Varroa is one of the biggest contributors to honey bee decline in the United States. The mite latches on to honey bees and feeds on their fat bodies, draining nutrient reserves, and spreading disease throughout a colony. The mites primarily target honey bee larvae, and reproduce by laying their eggs directly on honey bee brood. As honey bee colonies begin to rear large amounts of brood in spring mite populations also increase exponentially. For this reason, it is important to treat for mites before a colony begins its spring uptick in brood rearing. There are many ways beekeepers treat for Varroa, which vary both in their efficacy combatting Varroa and in their lethality to the honey bees themselves. One of the most common treatments are Apivar strips because they are easy to use, relatively benign for the honey bees, and deadly to the mites. The strips can be easily hung in a honey bee hive and paralyze mites, preventing them from feeding. Because the active ingredient in Apivar is an arachnicide, it acts on the spider-like mites without causing excessive harm to the honeybees, and also does not linger for long in the hive once removed.

Though winters are an energetically demanding time for honey bees, and the early days of spring can be dangerous with temperature fluctuations and limited flowers (especially in New England where we get snow in April!), beekeepers can take an active hand in ensuring colony success. By supplementing food in early spring, treating colonies for mites, and being careful to leave some honey for the bees during fall collections, beekeepers help their colonies start the year on a strong footing and remain healthy and productive all year round!