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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.

Shrews love a bee hive

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.

Amazing appetites

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.

The following photos showing shrew damage in a winter hive are courtesy of Phillip Cairns of MudSongs.org.

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Phillip-Cairns-shrew-damage-2
Phillip-Cairns-shrew-damage

Rusty
HoneyBeeSuite

Comments

Phillip
Reply

Hi Rusty,

The desiccated remains of honey bees that have been sucked dry and chewed to pieces by shrews are easy spot. I have several photos that illustrate it well if you’d like use them.

Rusty
Reply

Thanks for the photos, Phillip. I will get them up soon as I can. I’m having computer issues today, so I’m using my old clunker. It works about as well as an abacus for blogging, as in slow and boring. I type a word and then wait for it to appear . . .

Jason
Reply

Has anyone ever tried an electric fence line across the landing board?

Lee Alley
Reply

Very interesting. I am near Seattle and no one in our large club has ever mentioned shrews as an issue with our honey bee hives. Thank for a surprising revelation about the shrews.

Helen
Reply

If it was me, then I would be trying to work out some kind of baffle to stop them climbing up the legs of the hives in the first place, a bit like the baffles people in the UK often employ around the posts of bird feeders. My significant other is the beekeeper and definitely puts mouse guards on, though at the moment its war on wasps that is keeping him happy!

Not heard yet of shrews being a problem but they are fascinating and ferocious little creatures.

Enjoy reading your articles, keep them coming!

David Todhunter
Reply

I’ve had a problem with shrews in central New Jersey so it is a fairly widespread problem although here often misdiagnosed as mice.

Great blog. Thanks,

Phillip
Reply

The worst part about the shrews is that I had no idea they were a problem. I never read much about them and none of the experienced local beekeepers ever warned me about them. I’ve had mice in my hives, but at least the mice don’t eat the bees. Once a shrew finds the hive, it will keep coming back and gradually eat away at the cluster until it’s too small to survive. My smaller sized colonies that were started from swarms but normally get through the winter okay, didn’t have a chance.

I’ve since heard about a commercial beekeeper in a nearby province who lost 200 of his 300 colonies to shrews. He remembers seeing what he now recognizes as shrew tracks in the snow (I saw them too) going to and from his hives. The snow was high enough to give the shrews perfect access to the bottom entrances of the hives. They just walked in. Consistent cold temperatures and regular snowfall helped maintain the level of the snow crust. The snow never melted or compacted down, so the shrews has easy access all winter long.

That’s speculation at the moment, but it doesn’t seem too far fetched from what I experienced with my hives too.

I plan to staple quarter-inch mesh over all my hive entrances as soon as the bees stop bringing in pollen.

Lindy
Reply

This may not work in frozen regions – maybe use an infared water scare crow that makes some noise, as they are sensitive to sound and don’t want to get wet. I bought a water scare crow to deter nocturnal cats from pooping in my yard, but I forgot to adjust the sensitivity, so birds, mice, squirrels all got sprayed. The scare crow can easily be moved and the spray direction with intensity can be adjusted, also.

Have not had any winter bee predation, so have not tried my suggestion.

Lindy
Reply

I should clarify that the nightime scare crow was used in the front yard before I started beekeeping. The cat learned to avoid my yard, so I removed the scare crow.

Christine
Reply

I lost two hives to shrew damage in February. I saw it happening in November but did not know what I was seeing. I am only in my second season of beekeeping but have been reading up on it for more than twenty years and have never seen anything or heard anything about this problem until I happened across an old beekeeping book from the 1800’s that spoke of it. When I looked back at the videos I had taken it seemed pretty clear that this was my problem. The above pictures provided look exactly like what I had going on. So now I know I’m not crazy. Thanks

Ingrid
Reply

I have two shrews in my hive right now. I saw them, the little monsters! I have put small screen in the entrances of the hive. Big enough for the bees, but too small for the shrews. The problem is I have trapped the shrews in the hive. I am hoping they will die of thirst. Is this a good idea?

Rusty
Reply

Ingrid,

I don’t know for sure, but they may get enough water from eating bees and honey, or maybe from condensation. Will a mouse trap catch a shrew? I sometimes use mouse traps in my hives (for mice) and it works well.

Ingrid
Reply

I have four mouse traps out by the entrance of the beehive and as I finish setting up the last mouse trap I notice a shrew run right by them. I have the traps baited with peanut butter so I don’t think shrews like peanut butter. You did get me thinking about traps, though. I think I’m going to buy some sticky traps. I am not a big fan of these traps, but it is all I can think of that will catch the shews. It’s still too cold for the bees to be active, so I am not worried about the bees getting caught on the sticky traps.

Li
Reply

Ingrid,

If they are shrews, if you take off the screens they will leave and you can reattach the screens. They feed every 15 minutes but do not live in hives. Usually they will leave the hive quickly, taking the bee to consume outside. Sometimes they will eat in the hive but they don’t stay there. Mice, however. . .

Ingrid
Reply

The sticky traps aren’t working. Actually saw the shrew run right over the sticky part. A combination of too cold outside and the shrews weighing so little I think is the reason the traps don’t work. The shrew was running out of the hive, so I have put the screens back on and will look for signs of bee parts in the entrance way behind the screen. If no bee parts then there should be no shrews in the hive. Yeah!

Ingrid
Reply

Thanks for all the advice.

David Walsh
Reply

A good shew trap is a wine bottle with margarine put inside the neck of the bottle. They love margarine. Usually put a bit of water inside as well but hard in winter. Just lay the bottle on its side but with the neck slightly upward. They can’t crawl back out.

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