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Clearly a waste

The first line in the Huffington Post story reads, “An amateur photographer has captured an amazingly rare sight in his own back garden—a bee urinating.” No doubt, the photo by Mark Parrott is awesome, but is the bumble bee actually urinating?

In fact, the bee digestive system does not divide waste into solids and liquids—instead, all of it is collected in one place. The bee digestive system is more or less a straight line.

The mouth is connected directly to the esophagus, and the esophagus extends through the head and thorax all the way back to the abdomen. In honey bees, after food goes through the esophagus it travels into the crop (or honey stomach) where it is stored for transport back to the hive.

At the end of the crop is a one-way valve known as the proventriculus. Anything that passes through this valve moves on to the ventriculus (also known as the true stomach or digesting stomach) where it is digested. But anything that goes through the one-way valve cannot go back the other way. So food that is digested cannot re-enter the crop, and this is why nectar is not bee vomit. Nectar that will be used to make honey never makes it into the digesting stomach, only the crop.

The ventriculus is lined with cells that secrete enzymes that digest any nectar and pollen that has passed through the one-way valve. At the far end, the ventriculus is attached to the ileum, which is like a small intestine.

Right where the ventriculus meets the ileum, about one hundred malpighian tubules connect to the digestive tract. Malpighian tubules act like our kidneys. Just like our kidneys filter waste products from our blood, the malpighian tubles filter waste products from the bee’s hemolymph. This liquid waste, which is analogous to urine, is dumped into the ileum where it joins the solid waste from the ventriculus.

The ileum removes nutrients from the digested food and moves the waste further along the digestive tract. From the ileum, the waste products from both the ventriculus and the malpighian tubules move into the rectum where it is stored until the bee can defecate through the anus.

All bees are built in a similar way, but the crop is more developed in those species that carry nectar back to the nest. The flow of food and waste through a honey bee looks like this:

mouth↔esophagus↔crop (honey stomach)→proventriculus (one-way valve)→ventriculus (digesting stomach)→ileum (intestine)→[waste from malpighian tubules joins food waste in the ileum]→rectum→anus

 

So back to the photo, I would say the bee was defecating rather than urinating. But clearly she had a lot to drink that day. Who knows? Maybe she was getting ready for a mandatory drug test and was trying to flush away all the poppy nectar she drank.

Rusty
HoneyBeeSuite

The blaming of the shrew

Athough I’m not a hundred percent sure, I believe we are blaming the wrong shrew for damage wrought on bee hives in Canada and northern parts of the United States. Both Fletcher Colpitts, Chief Apiary Inspector of New Brunswick, Canada, and the Bee Informed Partnership website are blaming the European pygmy shrew, Sorex minutus, for the destruction. However, I can’t find evidence that the European pygmy shrew even lives in these areas. It seems more likely that the native species, the American pygmy shrew, Sorex hoyi, is the culprit.

According to the Smithsonian National Museum of Natural History, the American pygmy shrew is found throughout much of Canada and in certain northern parts of the United States. It is an extremely small mammal, averaging about 3 grams when fully grown. According to the University of Michigan, this shrew can grow to about 90 mm in length, although about a third of that is tail.

The problem for northern beekeepers is that the pygmy shrew, which survives on a diet of invertebrates, has discovered that honey bee hives have much to offer: a nice warm place to eat with lots of fresh meat on the menu. They can squeeze through a hole less than 1 cm in diameter, so standard mouse guards won’t keep them out.

I didn’t know anything about shrew predation until I began asking other beekeepers what I was seeing last winter. During the coldest months, when no yellowjackets or similar predators are around, I was finding legs, wings, and headless bees with hollow thoraxes on the landing board of one particular hive. Other hives in the area were unaffected. Each day I would brush the entrance area, but by the next day the body parts reappeared.

Phillip Cairns, a beekeeper from Newfoundland and author of Mudsongs.org suggested it might be shrews, and I believe he is correct. Not only is the evidence consistent, but I see dead shrews once in a while—courtesy of my cat—so they definitely live in my area.

Shrews apparently have a very high metabolism and have to eat constantly in order to keep going through the winter. From accounts I’ve read, the shrews hunt at the outer surface of the honey bee cluster, snatching those bees that are cold and slow. Once captured, the shrews like to consume the contents of the thorax. They get into the thorax by pulling off the bee’s head or drilling a hole right through the exoskeleton, leaving it hollow, and scattering wings and legs in the process. They also leave a trail of fecal matter wherever they go.

Those who have dealt with shrews in the past find that a quarter-inch mesh (6 mm) will keep them out. The problem with quarter-inch mesh is that it will knock the pollen loads from the honey bee’s legs, so it can only be used when pollen collection is not occurring. At other times, a larger mesh must be used, at least 3/8 (10 mm).

In the past, Phillip has lost a number of hives to shrew predation. My colony survived the winter, although it was small and slow to get restarted in the spring. When I opened the hive on a warm day, I did not find a shrew, but I did find many more of the hollowed out bodies and piles of poop, especially on the top bars. It is still not clear to me whether the shrews spend the winter in there the way mice do or if they come and go, but they definitely disappear in spring when the bees get feisty enough to chase them away.

I will definitely be screening that one hive and maybe the ones near it. And if anyone can shed light on the species issue (Sorex minutus vs. Sorex hoyi) I’m eager to know the answer.

Rusty
HoneyBeeSuite

Notice Board . . .

In case you missed it: A Song of the Bees

How to recognize a nectar dearth

“How can I recognize a nectar death?” is a common newbee question and a hard one to answer. I think most experienced beekeepers know which plants are in flower in any season, which bloom follows another, and how long each lasts. They are attuned to variations in the weather from year to year, and they know if things are early or late.

Here in the coastal Pacific Northwest, we can expect the summer dearth to follow the blackberry bloom—an event that coincides with the beginning of the dry season. But if you dropped me in the middle of Texas, Alberta, or Kentucky tomorrow afternoon, I wouldn’t know the plants, the weather patterns, or the rhythm of the seasons. Read more

How much honey should I leave in my hive?

How much honey will your bees need for winter? Good question. But before I answer, here’s a question for you: How much heating fuel will my household use this winter?

Well, you say, that is complex. It depends on where you live, your local climate, and the size and geometry of your house. It depends on what type of furnace you have, how warm you like it, and how many people live there. It depends on how much insulation you have, and whether you have wind breaks, and what color it is. It depends on air leaks and ventilation and the materials it is made from. It depends on whether the seasons are early or late. And on and on.

Your bee colony has different issues, of course, but just as many. The climate and weather, the amount of ventilation, the structure of the hive, the number of bees, the kind of bees, the number of warmish days and the number of abnormally cold ones are some obvious examples. The fact is, you can’t predict exactly how much honey a colony will need, so it is better to estimate on the high side.

I checked dozens of sources this morning and found an amazing amount of agreement on general guidelines. Bees in the southern U.S. may thrive on as little as 40 pounds, bees in the middle states need about 60, and northern bees may require 80 or 90. Those are average numbers for average years and average hives. What’s average? Another good question.

In all but the warmest areas, I recommend that a beekeeper leave 80 to 90 pounds. In nearly all cases, this will assure a good supply of natural food for your bees, and it will save you messing around with syrups and sugars and supplements. In short, it is good for them and good for you.

The Mann Lake catalog used to have estimates for the weight of full boxes. According to them, a full ten-frame deep weighs 80-90 pounds, and a full ten-frame medium weighs 65-75 pounds. Discounting the weight of the structure and dividing by 10, a full deep frame holds about 8 pounds of honey and full medium holds about 6 pounds. (If you evenly space nine frames in a ten-frame box, a full frame will weigh a bit more.)

According to Caron and Conner (2013), the ideal fall colony will have brood in the center of the lowest box. This will be flanked with frames of honey and pollen, and the two outermost frames will be filled with just honey. The second deep will be filled to the brim with honey—all ten frames.

Applying the math to their ideal colony, you will have 12 deep frames completely full of honey which gives you (8 x 12) or 96 pounds, plus any additional that is stored on the pollen frames.

This setup should get you through any winter, but in the more temperate states, you could easily replace the second deep with a medium, which would give you (6 x 12) or 72 pounds of honey plus any additional on the pollen frames.

A common error that new beekeepers make is harvesting the honey supers without checking the brood boxes for honey. You cannot assume the deeps are full just because the honey supers are full. Often the bees use one or both brood boxes for brood and pollen during most of the season. Not until late in the year do they start moving the honey closer to the brood nest. If you take the supers without checking, you could be leaving your bees with almost nothing for the winter. So above all, remember to look before you take.

Rusty
HoneyBeeSuite

A-full-frame-of-honey
A full frame of honey. © Nancy McClure.