My next door neighbor, Allison McElroy, called me over the other day to show me a bumble bee colony she found in her yard. The traffic through a small hole in the ground was flowing much more freely than most other parts of the Lehigh Valley at that time of day.
All of the bumble bees that were buzzing through the hive entrance were the offspring of a single queen. After hibernating through the winter, the queen spent the first few weeks of spring frantically looking for some suitable real estate, like an abandoned chipmunk burrow.
The solo queen spent her early spring days gathering as much pollen and nectar as she could and used the nutrients to produce a clutch of about a dozen eggs. She made a little wax pot to store up any extra honey she could produce from the nectar she collected, but it was never enough to last more than few days.
A few weeks into spring, she spent much of her time feedng her newly hatched babies with pollen that she collected from spring flowers. When it was cold, she would take little sips from her honey pot. She would burn this fuel to increase her body temperature. This would keep her little grub-like larvae cozy and snug under a bare patch on her abdomen.
Her gathering expeditions had to be kept as short as possible. She was needed at home to keep her little larvae warm. Queens typically toast their tots at around 85 degrees F. Lower temperatures stunt their growth. Next time you watch a bunch of bumble bees working on a patch of flowers, notice that some of them are much larger than others. They are probably all workers. Their adult size is largely dependent on the conditions of their larvae-hood.
Near the top of her springtime checklist, Allison's queen had to defend her nest from other jealous queen bumble bees. They wanted to set up their own nurseries in the same abandoned burrow. The competition was fierce. All the competing queens would die if they were unable to find a nest site. It was a hard knock life.
As spring eased into summer, the living got easier for the queen bumble bee. The ground got warmer, so she didn't need to spend so much time and energy incubating her larvae. She also began to get some help from her new and fully grown worker bee daughters. These workers fed their little sisters with pollen that they collected from dawn to dusk, rain or shine. Life is short for worker bumble bees. They only live for a couple of weeks.
By now, the population of Allison’s colony has probably grown to about 500 bees. The cicadas tell us we are heading into the dog days of the summer. The queen has probably started to lay eggs that will hatch into larvae that will be specially raised to become new queens. The princess-like larvae are fed super-sized servings of pollen by their sisters. This extra nutrition allows them to fully develop into reproductive adults.
Around this time, the queen will also “decide” not to fertilize about 100 of her eggs. These eggs will develop into males, or “drones;” The males head off and fend for themselves as soon as they are able. They will be spending their next few months looking for some brand new queen bumble bees to fertilize before the winter comes.
Come winter, the original founder queen will die, along with all of the workers and males. Only the new queens will survive the winter, hunkering down in the comfiest, most insulated underground spots they can find. Next spring, the surviving queens will start searching and competing for new abandoned rodent borrows in which to build a nest. Even though as many as 100 queens may be raised in the original colony, the odds are that only one of them will successfully start one of her own. What a great premise for a new reality show.
Between their portly black bodies and fluffy yellow midriffs, my neighbor’s bumble bees resembled furry Carpenter Bees. I took a few pictures to get a positive ID. They turned out to be the Eastern Common Bumble Bee (Bombus impatiens). This cuddly bee is native and very common in most eastern states.
Identifying Allison’s bumble bees was not hard at all. There is an excellent bumble bee identification guide available from the USDA and the National Park Service. It does not require any prior knowledge about bees and has lots of very useful information. I have posted it along with this blog.
Using this guide, I found there are only two very common bumble bees that are likely to be seen in our city environment. About six to eight more can be spotted in more rural settings of the Lehigh Valley.
Just one decade ago, identifying Allison’s bumble bees might have been more of a challenge. Now, the Rusty Patched Bumble Bee and the Yellow Banded Bumble Bee have become so rare that “wanted posters” have been made for them. These were produced as part of the Bumble Bee Conservation Initiative of the Xerces Society. If these bumble bees were the proverbial canaries in the coal mine, all six legs would be sticking straight up in the air.
Bumble bees are not just important pollinators for wildflowers. Tomato plants need to be pollinated by bumble bees in order to produce fruit. Honey bees just don’t do the trick. Bumble bees have an amazing habit called “buzz pollination.” They grab onto a flower, uncouple their wings from their powerful flight muscles and then vibrate like crazy. This causes the pollen to dust their big and fuzzy bodies, which is then packed into pollen baskets on the bee’s legs and carried back to the nest.
Bumble bees are well suited for farm labor. Since they can raise their own body temperatures, they work in weather that is too cold, wet or windy for other bees. They also work for longer days and for a more extended season than honey bees. Bumbling from flower to flower, bumble bees are extremely efficient tomato, blueberry, cranberry and other crop pollinators.
Bumble bees do not produce honey in harvestable quantities. According to bumble bee economist Bernd Heinrich, “honey is money” if you are bee. By this standard, bumble bees are truly humble. Only honey bees can invest their energy stores in the form of honey stocks. Bumble bees lead a more hand-to-mouth existence, never being able to save up for more than a few pennies worth of honey for torrentially rainy days.
Only young bumble bee queens survive the winter. In contrast, honey bee colonies keep a large number of workers, which dote over the queen on a year-round basis. This is why honey bees are such fastidious hoarders of honey. This rich energy source tides them over during the lean months.
One benefit of the bumble bee’s relative poverty is that do not need to invest in an expensive security system. Honey bee colonies employ relatively aggressive guards that always die after delivering a painful sting. They need to protect their wax encrusted Fort Knox of golden calories. Female bumble bees can sting people, but they usually won’t unless they sense a direct threat.
The bumble bee economy of the past decade has been especially tough. Four American bumble bee species have gone from being very common to rare or extinct. This sudden loss of bumble bee diversity took the bumble bee experts by surprise. The cause or causes are still being puzzled over, but seem to be distinct from the eerie colony collapse disorder that still plagues our nation’s honey bee supply.
Land use might be part of the problem. Farmland that was covered with clover and other “weeds” and wildflowers has been turned over to crops or shopping malls that are not as interesting to bees.
Certain pesticides, especially neonicotenoids have been associated with some of the problems that our honey bees have been coping with. There is no doubt that they have put some additional stress into the lives of our bumble bees, as discussed in a recent Science magazine article.
Jordanna Sprayberry is a neuroscientist who studies bumble bees at Muhlenberg College, here in the Lehigh Valley. Her research team has been investigating the effects of various pollutants on the ability of bumble bees to forage. Their recent studies have shown that a wildly popular fungicide called Manzate can interfere with the ability of bumble bees to find their food. A noisy “aromasphere” makes the hard work of bumble bees even harder.
A fungal parasite of bumble bees called Nosema bombi has been in the recent spotlight. This fungus essentially wiped out the once abundant Western Bumble Bee in the 1990s. The fungus does not always kill the bumble bees outright, but it can weaken the colonies and make them more vulnerable to other insults.
A recent report from the Xerces Society plainly stated that the “most likely cause of the introduction and spread of [Nosema bombi] is the international and interstate transport of bumble bees by the commercial bumble bee rearing industry.”
Most bumble bees that are used in commercial greenhouses are delivered in cardboard boxes. They are raised in highly specialized bumble bee rearing facilities that are capable of producing industrial quantities of the bees.
The circumstantial link between bumble bee declines, industrially-reared bumble bees and Nosema bombi infections was analyzed in a highly respected research journal. The researchers argued that stricter safeguards and regulations are urgently needed in order to thwart the spread of new and uncharted infections.
Koppert Biological Systems is one of the largest players in the boxed bumble bee business. I spoke with a Koppert salesperson. He told me that they only raise American-born Bombus impatiens at a USDA-inspected facility in Howell, MI. He pointed me to the disease testing procedures that are used in their European facilities. He could not tell me how their bumble bees were screened for diseases here in the U.S., but assured me they are appropriately tested. The hives they sell for outdoor use only contain sterile workers. The ones they sell for greenhouse use come with a built-in “queen excluder.” This device prevents the domesticated queens from getting out and cavorting with wild bumble bees, and vise versa.
Bombus impatiens are known to build especially large colonies and seem to be resistant to pathogens that may have killed off some of our more susceptible native bumble bees. It would a terrible thing if they muscled out any of the closely related native western bumble bees in their home territory. In light of this, some western states have outlawed or restricted the sale and use of pre-packaged eastern bumble bees.
I spoke with a salesperson at Arbico, a well-known distributor of beneficial insects. Would it be possible for them to ship a Koppert bumble bee hive to my mother, an enthusiastic gardener in Seattle, WA? Koppert’s role in the bumble bee story was recently featured in an informative Seattle Times article. “If she is not going to use them in a completely enclosed greenhouse, we cannot sell them to her,” was the essence of her reply.
Another on-line retailer was perfectly happy to overnight her some bumble bees, just as long as they were used in a… wink-wink… “greenhouse.” At least he warned me that she could be fined if she was caught using them outside. My mother never received any boxes of live eastern bumble bees.
State agricultural laws are not always very well advertised and are costly to enforce. Meanwhile, boxed bumble bees are still marketed as “natural pollinators” to well-intentioned homeowners. All that glitters is not green.
Meeting my neighbor’s Bombus impatiens made my day. It inspired me to read Bernd Heinrich’s illuminating book on bumble bee economics. From this, and conversations with my mother, an avid bumble bee fan, I was introduced to the hidden and challenging lives of these cuddly canaries in the coal mine.
Allison’s bumble bee colony was started by a single queen. After surviving the winter without any help from worker bees, her bustling career didn’t take off until last spring. Six to eight months old, she was already a senior citizen in bumble bee years. Resourceful and good at multi-tasking, she started the season by collecting pollen and nectar to feed herself and then her young. She made and labored to fill a little wax honey pot, which she kept as a piggy bank for energy reserves. She valiantly defended her nest against interlopers. On top of all this, she kept her first batch of babies warm by metabolically burning her meager supply of honey.
The sustainble reward for all of her effort is that just one of her daughters will beat the odds, overcoming both natural and manufactured obstacles, and start her own colony. After learning more about the struggles of bumble bees, I resolved to improve the bee friendliness of my own garden. I hope that at least one of the daughters of Allison’s queen bumble bee will make her mother proud.
This work by Marten Edwards is licensed under a Creative Commons Attribution-NonCommercial-NoDerivs 3.0 Unported License.