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Bumble bee answers every beekeeper needs

Bumble bees are among the earliest bees of spring, so it won’t be long before beekeepers begin to hear the inevitable questions. Honey bee keepers, it seems, are expected to know all the answers, so here’s a short refresher to get you started.

Where do bumble bees go in winter?

Bumble bee colonies do not survive through the winter except in very warm climates. Normally, a colony begins to raise both queens and males in late summer. Once a virgin queen mates, she fattens up for the winter and seeks a sheltered place to hibernate until spring, much like a bear. She may burrow into the ground or, depending on the species, she may select a warm and secure above-ground cavity. The remainder of the colony dies, usually with the first hard freeze.

Do bumble bees live in hives?

Bumble bees do not live in man-made hives the way honey bees do. Most bumble bee species live in an underground cavity. Usually these holes were dug, and later abandoned, by a mammal such as a mouse. In early spring after the queens emerge from hibernation, you can often seem them scouring the ground, looking for the perfect nesting spot. Some species prefer above-ground accommodations, such as birdhouses, mailboxes, or slash piles. Occasionally, you can coax a queen to nest in a specially-designed bumble bee box, but it is difficult.

Do bumble bees swarm?

Although bumble bees live together in colonies headed by a queen, the colony does not divide and swarm the way a honey bee colony does. Instead, colony reproduction occurs in the fall when new queens are produced for the following year.

How long does a bumble bee live?

A queen bumble bee emerges in the fall, mates, hibernates, and raises a colony. The entire cycle lasts one year and then she dies. The other bees in the colony—the workers and the males—live much shorter lives. The workers can live perhaps two to three months, but the males die soon after mating.

What does a bumble bee eat?

Bumble bees are generalists when it comes to food, drinking nectar and collecting pollen from a wide variety of flowering plants. The nectar is consumed for energy, while the pollen is used as a protein source. Much like honey bees, the workers feed pollen mixed with glandular secretions to the young larvae.

Do bumble bees sting?

Female bumble bees, both queens and workers, can deliver a powerful sting. Unlike honey bees, the females can sting repeatedly. Their sharp, smooth stinger can easily slide back out of tough skin in preparation for delivering the next punch. Male bumble bees, just like all other male bees, cannot sting because they don’t have a stinger.

How do you collect their honey?

The queen bumble bee stores a small quantity of honey in wax pots that she builds inside the nest. She works hard to fill these pots with nectar so that when she starts to raise brood, she can stay in the nest until the first brood reaches maturity. Much like a broody hen, she careful tends her young family, keeping the developing bees warm with her body. The honey in the pots may be her entire food supply while she raises the first workers.

Unlike honey bees, bumble bees do not collect surplus nectar and have no need for a winter food supply. The small amount of nectar used by the queen is not enough to collect and, in any case, taking it might destroy the new colony.

Are bumble bees endangered?

All bee species are endangered to some extent, although some are more imperiled than others. Bumble bees have been particularly hard hit by habitat loss, pesticides, imported diseases, and a lack of forage. It is best not to kill any bumble bee, especially if you don’t know the species. A number of once-common bumble bees are now on the brink of extinction, so give them the benefit of the doubt and let them carry on.

Do bumble bees get colony collapse disorder?

Colony collapse disorder (CCD) is a term used to describe a honey bee problem. Because honey bees and bumble bees are so different, the term CCD does not apply to bumble bees. Most notably, bumble bee colonies do not overwinter so annual colony losses, as measured by beekeepers, do not occur.

However, some of the conditions thought to cause colony collapse, also affect bumble bees. Introduced diseases and parasites, lack of good-quality forage, loss of habitat, habitat fragmentation, pollution, climate change, and pesticides have all been suspects in colony decline and each of these affect bumble bees as well as honey bees.

Do bumble bees get Varroa mites?

Bumble bees are not bothered by Varroa destructor because the life styles and life cycles of these two species are very different. However, bumble bees have their own array of mites to contend with. Luckily, most of these mite species are relatively harmless to bumble bees. Although they latch on to bees for transportation to a new nest, they feed on bits of pollen and other nest debris instead of on the bees themselves.

You can often see mites clinging to foraging bumble bees. Single mites, or sometimes whole groups, ride the bee. The mites then jump off onto a flower where they await the arrival of another bee to carry them to a new nest.

The flower becomes an airport, of sorts, where mites flip through their messages and impatiently wait for a connecting flight. Sometimes, though, a mite infestation can become so heavy that a bumble bee has trouble flying. This may be temporary until the mites jump off, but in the meantime, the flight-impaired bee may succumb to predators like birds or frogs, or it may weaken, unable to gather food.

I found a bumble bee that cannot fly. What should I do?

Usually, nothing can be done for a bumble bee in distress. Things we can’t see may be affecting her health, including diseases, internal parasites, or poisoning. If the bees’ wings are tattered or her hair is worn, she might be dying of old age.

Still, sometimes a bee is just momentarily stranded and a little TLC can get her going again. I’ve seen bees fly into windows like birds and remain stunned for many minutes before they fly off. Or, if a bee is grounded due to mites, you can gently brush them off. If it’s energy she needs, you can dissolve a spoonful of sugar into a couple spoonfuls of water and put some right in front of her.

How can I help bumble bees?

All bees need the same things: a continuous supply of flowers, water, nesting habitat, and nesting materials. So the best way to help bees is to make sure those things are available. Grow lots of different flowering plants, especially those native to your area. Make sure you have a source of water, even if it’s just a drippy hose or leaky faucet. Leave patches of landscape unmowed so bees can find safe places to live and grassy materials to use in their nest. Above all, stop the use of insecticides and herbicides: fewer chemicals in the environment make the planet better for everyone.

Now you are ready

Okay, beekeepers, now you are ready to go forth and answer questions about bumble bees. And for an excellent book about the these amazing creatures, I highly recommend A Sting in the Tale by Dave Goulson. The author is a world authority on bumble bees and an excellent writer. He makes everything about these bees fun to learn.

Rusty
Honey Bee Suite

Mites-on-a-bumble
The two tan-colored objects on this bumble bee’s thorax are mites. Most bumble bee mites are harmless to the bee and actually eat nest debris. © Rusty Burlew.

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Officially endangered: the rusty-patched bumble bee

It’s official: the US Fish and Wildlife Service has listed the rusty-patched bumble bee, Bombus affinis, as an endangered species. This bee, in the family Apidae, is the first insect from the continental United States to make the list. Last year, seven species of Hylaeus were the first bees to make the list, but they occur only in Hawaii.

Like many things that were once abundant such as bison and passenger pigeons, it was easy to take the rusty-patched bumble bee for granted. It was once a common sight in eastern North America, occurring in 28 states and 2 provinces. But populations began to crash in the mid-1990s. The most recent data, collected in the early 2000s, show small populations remaining in only 13 states and Ontario, a decrease in range of about 87%.

Small populations lose genetic variability

Since no thorough counts have occurred since the early 2000s, populations are likely even lower. In fact, very few colonies have been spotted in recent years. When colonies are few and far between, outcrossing between non-related colonies is less likely to occur and inbreeding increases. Loss of vigor, often called inbreeding depression, makes the colonies more prone to disease, stress, and poor nutrition among other things.

Since accurate data on insect populations and distribution was not a priority in the past, little data is available to show trends over time. Many entomologists suspect that the number of rusty-patched bumble bee colonies was declining long before it came to anyone’s attention.

A large bee with a short tongue

The rusty-patched bumble bee is one of the large bumble bees. According to Bumble Bees of North America (2014) it is a short-tongued species that prefers to live in prairies, woodland, marshes, parks, urban gardens, and agricultural areas. They prefer to nest in abandoned burrows that once belonged to chipmunks or rabbits.

The rusty-patched bumble is polylectic, meaning it forages on a wide range of flowering plants. Depending on the local climate, individuals may be seen from April through October, but it is most abundant in July and August.

Habitat loss is crucial

According to a report by the Natural Resources Defense Council, the primary reason for the population decrease is habitat loss. But other factors such as the disease Nosema bombi, which has spread from commercial bumble bee stocks, may have had a large impact.

Other detrimental conditions include heavy use of pesticides, habitat degradation, loss of forage, and climate change. Climate change causes mismatched timing between flowering plants and the bees that depend on them. It may also cause increased flooding that destroys underground burrows, and prolonged drought that can interfere with the food supply.

Ultimately, as colonies become more scattered, the dynamics of small populations—like inbreeding depression and large numbers of sterile males—causes what is known as an extinction vortex. An extinction vortex is easy to visualize: just imagine a population of any animal swirling around a drain until it finally disappears. As the number of individuals gets lower and lower, the remainder disappear faster and faster.

How can you help the rusty-patched bumble bee?

The US Fish and Wildlife Service lists three things that anyone can do to aid the rusty-patched bumble bee. But the most important thing to remember is that these three items can help any population of pollinator, no matter where you live.

  • Plant flowers that will bloom from early spring through fall.
  • Provide a safe place for overwintering. In other words, leave some areas of your yard undisturbed all year long. That means no tilling, no raking, no removing dead stems.
  • Avoid pesticides, especially insecticides and herbicides.

According to Bumble Bees of North America, the rusty-patched bumble bee prefers flowers in the following families: Aesculus, Agastache, Dalea, Eupatorium, Helianthus, Impatiens, Lonicera, Monarda, Prunus, Solidago, and Vaccinium. Do your part for the remaining pollinators and plant a wide diversity of flowers.

Rusty
Honey Bee Suite

The rusty-patched bumble bee has been listed as endangered by the US Fish and Wildlife Service.
The rusty-patched bumble bee has been listed as endangered by the US Fish and Wildlife Service. Photo by Dan Mullen. The original photo can be seen on Flickr.

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Planting a garden for leafcutting bees

Whenever I write about leafcutters, someone from the Entomological Society of America writes to remind me that the official common name is “leafcutting” bees. To me, the phrase “official common name” is an oxymoron. The official name is the Latin scientific name, and the common name is what the local people call it.

I understand that entomologists want to reduce confusion, but isn’t that what the Latin name is for? I simply love to hear local variations in names. Furthermore, I think that insisting on a “official” common name destroys a rich treasure trove of vocabulary.

My favorite example is a gem. The group of insect pollinators that we northerners call “hover flies” are often referred to in the southeastern states as “steady bees.” Now granted, a hover fly is not a bee, but once you see one of these creatures defy gravity, you know exactly what either group is referring to, right?

Leafcutters are fun to watch

As winter approaches I like to think about my pollinator garden. This year I’m fixated on leafcutters. As far as wild and native bees go, I think the leafcutters are one of the most charming groups. The way they hold up their pollen-coated abdomens is absolutely endearing. Their arched backs always remind me of gymnasts and dancers.

Two summers ago, in 2015, I had a succession of leafcutter species all season long, one right after the other. This past year, I had some but not nearly as many. So I’ve been doing some research to find out exactly what to plant for them.

Leafcutting bees are closely related to the so-called mason bees. They are both in the family Megachilidae (which means “large jaws”). Most of these species live in cavities, so it is easy to get them to nest in tubes, reeds, and straws.

Most of the leafcutting bees are in the genus Megachile (meg-uh-KYLE-ee). They collect and store pollen much like other natives, but they cut circles out of leaves and petals to use for nesting materials. If you are quick, you can sometimes see them carve the discs and fly away with them. Or you can see them arrive at their nest and force the piece into the nesting tube. The pieces are used to line the nest, build partitions, and close off the entrance.

Alfalfa leafcutters are small and quick

Most often we hear about the alfalfa leafcutting bee (Megachile rotundata), an introduced species. They’ve escaped from the alfalfa (lucerne) fields they were imported to pollinate, and now they occupy a wide range of habitats. These small bees are quick and not nearly as spectacular in appearance as some of the native species, but they are still fun to watch.

I will never forget standing in an alfalfa leafcutter domicile in eastern Washington, inhaling the fragrance of fresh-cut alfalfa wafting from the nests. The leafcutters zoomed to and from the domicile with the frenzied gentleness of a honey bee swarm, completely ignoring me.

Most of the leafcutters I have here at my place are larger than the alfalfa leafcutters, more similar in size to a honey bee. But leafcutting bees have a different physical presence. As I mentioned before, they hold their abdomens aloft, giving them an arched appearance. And they often hold their wings out to the side as they forage. Their abdomens are large, rounded on the bottom, and often laden with pollen.

Attract leafcutters with the things they need

To attract leafcutters to your garden, you need to provide the things most bees require: sources of pollen, nectar, water, nesting sites, and building materials. Having watched leafcutters for a number of yeas, I’ve noticed that the flowers they forage on are not necessarily the same ones they use for building. I want to provide both, if I can figure out what those are.

Last year, my leafcutters loved cosmos for both building and foraging. They adored the blue bells (Campanula) for foraging, but I never saw them build with it. They used the leaves of my Clematis but never touched the flowers. This year, they frequently foraged on the open-centered dahlias, sunflowers, mints, and phacelia but never harvested any discs from those flowers. Many leafcutters love to build with the petals of Clarkia (farewell-to-spring) and some species use Clarkia exclusively.

Of course, many leafcutters get sprayed for stealing bits of rose and lilac leaves. This is sad, of course, because, although the leaves look like they were hit with a shotgun, the plant is not permanently damaged. I’ve also seen leafcutters use both the flowers and leaves of Thunbergia (black-eyed susan vine) for discs, but I don’t know if they forage there. They also use the petals of partridge pea.

What else should I plant?

So far this fall I’ve order Clarkia and Cosmos for next year. I have the dahlia tubers from this year, and I hope to get some more Campanula. If you know of anything attractive to leafcutters, I would love to hear from you.

Rusty
Honey Bee Suite

Leafcutter-she-bee
This leafcutting bee is foraging on Phacelia. You can see the thick hairs on the underside of her abdomen. This area is used for collecting pollen. © Rusty Burlew.
Leafcutter
This is an alfalfa leafcutting bee. © Rusty Burlew.
Leafcutter-on-dahlia-4
This leafcutter is foraging on a dahlia. You can see her large mandibles (big jaws) and the edges of her hairy abdomen. Also note how she holds her wings out to the side while foraging. © Rusty Burlew.
Cosmos-with-bite-marks-Rusty-Burlew
This honey bee is foraging on a cosmos that was damaged by a leafcutter. © Rusty Burlew.

 

Why so many dead bumble bees?

Several of you have reported seeing many dead bumble bees on flowers, patios, or lying on the ground. This type of observation pleases me no end. It gives me hope to see so many people noticing wild bees and wondering about them.

As it happens, it is completely normal to see lots of dead bumble bees at this time of year. Unlike honey bees, most bumble bee colonies die at the onset of winter. Some colonies in warm climates may survive the winter, but as a general rule, a bumble bee colony lasts for only one season.

A colony starts with one bee

A bumble bee colony starts in the spring with a single mated queen. This queen hibernated all winter in a cozy protected spot, most often a narrow hole in the ground not much bigger than the bee herself. She survived on fat stored in her body, much like a bear or a hedgehog. You can often see these bumbles in the spring, remarkable for their ungainly size.

When the weather warms in spring, the queen feeds on the nectar of early flowers and cruises the countryside looking for a place to build her nest. The queens of most species choose an underground cavity—perhaps an abandoned rodent hole—as a shelter. In that hole, she begins the process of storing a little nectar, and building a small wax nest for her first batch of young workers.

Once the initial nest is fashioned from secreted wax, and tiny nectar pots are built and filled, the queen sits on her eggs very much like a hen. She keeps the brood warm with her body and drinks from her nectar pots until the young worker bees emerge from their cells.

The chores are turned over to workers

The queen works hard in the early spring, doing all the chores by herself. However, once the first workers emerge, she forages less and less. The labor-intensive jobs of brood rearing, foraging, and colony defense are turned over to her offspring, and she gets down to the business of egg laying. For most of the spring and summer this queen will lay eggs that produce nothing but more female workers.

Because of this system, nearly all the bumble bees you see in the spring and summer are workers. Like honey bees, they ply the flowers for both nectar and pollen, transporting the pollen back to their nests in baskets built into their rear legs.

In general, bumble bees have more size variability than honey bees. While all the honey bee workers in a colony are pretty much the same size, worker bumble bees come in a range of sizes. However, the smallest bumbles spend their entire lives in the nest, acting as nurses. It is only the larger workers that go out and do the foraging. Most of us never see the tiniest house-bound bumble bees.

Queens and males come later

Late in the summer the queen adds to the colony by producing both male bees and virgin queens. If you are observant, you can easily see the changes in your garden. The first thing you might notice is some huge bumble bees and an assortment of very small bumble bees, sometimes on the same flower. As you might guess, the large ones are queens. The small ones are males.

But wait. You never see honey bee queens and drones perusing the blooms, do you? So what are these bumbles doing out on the flowers?

Male bumbles have no home

The males spend their time trying to mate. Many males compete for this honor, but only a few get lucky. The rest of the time, they can be seen in the flowers, drinking nectar for quick energy. As it happens, they also sleep in the flowers because once they leave the nest they are not allowed back in.

Some people mention that these autumn bumble bees often look wet, lethargic, or dead. All of these may be true. The males don’t live very long, and after mating—or attempting to mate—they spend most of their time eating and sleeping. During the cool nights they get wet with dew and stiff with cold. Sometimes they warm up the next morning and live another day, or sometimes they get eaten, or simply die.

Queens fatten up for winter

The queens though, lead a different kind of life. During the fall months the newly-mated queens gorge on nectar and pollen, fattening up for winter. The more fat they can store, the better chance they have of making it through the cold months ahead. Once she is ready, a queen will go and find a nice protected hole where she can hibernate until spring.

Sometimes in the fall you will see a fat queen next to tiny male. Although they forage side-by-side, the difference in size is striking. By evening, however, you might notice dead males adhering to flowers, or dropping into the grass where they are quickly eaten by something else. In contrast, the queens are nowhere in sight, having flown back to the nest for protection.

The colony dies as winter sets in

Back in the colony, life is winding down. One by one, the newly-mated queens leave the nest to begin hibernation. The old queen slows her egg production and eventually dies. The workers die as well. The first hard freeze finishes off all the remaining bees except for the hibernating queens. As we go into winter, the once busy colony is but a memory.

Rusty
Honey Bee Suite

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Here two bumble bees, most likely Bombus vosnesenskii, share a flower. The large one on the left is probably a queen. © Rusty Burlew.
eight-bees
Seven honey bees and a bumble bee share a dahlia. © Rusty Burlew.

Megachile perihirta, the furry leafcutting bee

The furry leafcutting bee, Megachile perihirta, is one of my favorite pollinators because it is large and showy. From a distance, this bee could easily be mistaken for a honey bee. But up close, it is hard to miss the large abdominal scopa where the leafcutting female carries her pollen load.

About the size of a honey bee, these bees are native to the western parts of North America. They are summer visitors, often seen in July and August. Although they forage on many different plant species, they have a preference for flowers in the Asteraceae family.

Like all leafcutting bees, the female of this species cuts round sections of leaves and petals to line her nest and build divisions between the egg chambers. Although many leafcutting bees nest in hollow reeds and beetle borrows, this species prefers underground tunnels.

I wasn’t able to photograph a male, but the males have distinctive white “mittens” on their forelegs and a white face. Soon after they mate, the males disappear for the year and the females begin to work at provisioning their nests.

The open-centered dahlias that I mentioned in a previous post turned into a playground for these bees. The leafcutters work fast, flit around in the flowers, and pose beautifully. Yesterday, my camera sounded like it belonged to a fashion photographer. As the bees strutted around on their flowery runway, and I just kept snapping away, trying to capture the perfect expression.

Rusty
Honey Bee Suite

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The furry leafcutting bees have taken a fancy to the open-centered dahlias. © Rusty Burlew.
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Leafcutting bees have a characteristic posture, holding their abdomens high. © Rusty Burlew.
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A view from the rear. Leafcutting bees often hold their wings out to the side when they forage, something honey bees seldom do. © Rusty Burlew.
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Leafcutting bees have large mandibles, perfect for cutting leaves. In fact, the name Megachile means “large jaws.” © Rusty Burlew.
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Here you can see her tongue. Although these bees are polylectic and will forage on many different plants, they seems to favor those in the Asteraceae family. © Rusty Burlew.
Honey bee and M perihirta
You can see that the honey bee (left) and furry leafcutting bee are about the same size. © Rusty Burlew.