We all know that there are a variety of pests and diseases that impact honey bees. Often the first pest species that come to mind are varroa mites, or the devastating bear attacks. We often neglect to think about the small mammals that cause significant damage to honey bee colonies. Today’s blog will discuss why this group of small animals causes issues for beekeepers, and how they can be best managed.

Honey Bee Small Animal Pests: Mice, Skunks, Shrews, and Other Minor Pests

Mice inflict significant physical damage to honey bee hives. They do so by entering the hives in the fall and winter and cause extensive damage to comb and woodenware (Sammataro and Avitabile, 2021; Sarwar, 2016). Mice may feed on various components of the colony including bee bread, honey, brood, and adult bees. Additionally, the droppings and urine of mice can impact honey bee behavior (Sammataro and Avitabile, 2021; Sarwar, 2016). Mouse urine is particularly repellent, and it disrupts cluster behaviour. There are a few things to look for to know if you have mice in your colony, including: chewed comb and/or wood; mouse droppings on the bottom board; holes chewed through entrance reducers to allow mice to enter the hive; and nest material between frames (Sammataro and Avitabile, 2021; Sarwar, 2016). To minimize damage from mice, bees should be placed on stands, use entrance reducers, use metal mouse guards, and keep weeds down around the hives. It is important to note that bees placed near a forest or in fields of tall grasses are at a high risk for mouse damage (Sammataro and Avitabile, 2021; Sarwar, 2016).

Mouse nest in bee hive (Penn State Department of Entomology©)

Skunks are a serious pest of honey bees. They cause damage to both equipment and bees, and they dig up bee yards looking for food (Sammataro and Avitabile, 2021; Sarwar, 2016). Often these animals visit colonies at night, and they force bees out of hives by scratching at the entrances. If these animals repeatedly visit bee yards at night, there can be a significant decline in the adult population of honey bees. These mammals have been known to feed for an hour or more and this feeding activity causes bee colonies to become more defensive and aggressive (Sarwar, 2016). Some signs that skunks are visiting your bee yard include scratch marks and dirt on the hive front, outer covers off or skewed, and weak and/or defensive colonies (Sammataro and Avitabile, 2021; Sarwar, 2016). The best way to help manage this pest is to place bees on hive stands at least 18 inches high, which will keep bees out of reach of small predatory animals. Additionally, when hives are placed higher above the ground skunks must expose their bellies, and being stung on their underside deters them from the hive. Properly set up electric fencing will also protect against skunks.

Shrews are a major pest of honey bees in Atlantic Canada. There are seven species of shrew found in eastern Canada. When it comes to eating honey bees, the Common Shrew is the most likely culprit. Shrews have a very high metabolic rate and, unlike many small mammals, are not dormant or hibernating through the winter months. The result is that these insectivores will almost double their food intake to keep warm and active during winter. For these reasons, beehives must be protected against shrews while the bees are clustered and most vulnerable. It is required to protect honey bees in Atlantic Canada with the use of shrew guards in the winter months.

Other minor honey bee pests in Atlantic Canada include raccoons, squirrels, and rats. These animals cause similar issues to those mentioned above, and they can also be managed by using hive stands, entrance reducers, and electric fencing.

When attempting to manage small mammalian pests there are several things a beekeeper needs to consider. First, the beekeeper needs to be confident about what animal pest they are dealing with. This must be done by studying the signs left by the animal (Sarwar, 2016). Second, the beekeeper needs to consider how much damage might occur without any additional control and what are the benefits of control versus the cost of damage. Essentially a beekeeper needs to determine the economic threshold of the pest (Sarwar, 2016). Next, is the animal legally protected in a way that limits the action the beekeeper would otherwise take. Finally, will there be any impacts on non-target animals if a control program is implemented (Sarwar, 2016).

These small mammalian pests can be a serious concern for beekeepers. If not monitored and managed well, honey bees can be decimated by these pests. However, if honey bee colonies are kept strong and healthy, and you continually monitor and take the necessary steps to minimize damage, you can successfully manage these pest species in your apiary.

References

Sammataro, D., and Avitabile, A. 2021. A beekeeper’s handbook: fifth edition. Cornell University Press.

Sarwar, M. 2016. Predations on honey bees (Arthropoda) by vertebrate pests (Chordata) and control of nuisance. International Journal of Zoology Studies. 1(2): 12 – 17.

Connecting with ATTTA Specialists

If you’d like to connect with ATTTA specialists or learn more about our program, you can:

visit our website at https://www.perennia.ca/portfolio-items/honey-bees/

Email abyers@perennia.ca

Blueberry Update & Are You a Shrewd or “Shrewed” Beekeeper?

In preparing for winter many beekeepers will reduce hive entrances to enable the bees to better thermoregulate.  It is also a practice in our region to place shrew guards on our hives.  This week we enter the debate about whether or not these are necessary.

The 2020 blueberry harvest is complete, and we are getting some general idea of the success of this year's crop.  We have some comments below from our provincial blueberry specialists. 

Blueberry Update

Prince Edward Island

"Initial assessment of the 2020 harvest shows an expected lower than the five year average for the blueberry crop this year. The 5-years average is about 23 million pounds and the last couple years have been below this as a result of frost events, drought, and lower inputs due to the low blueberry price. I expect the significant drought this year to cause a low total crop year once again"

Cameron Menzies (PEI Dept. Agriculture)

Nova Scotia

"As we are heading towards the end of September, wild blueberry harvesting is completed for this season. This has been a challenging year across the regions. We had a very good bloom during the pollination season, and anticipated a great yield.  However, mother nature likes to bring challenges to agriculture and the dry and hot conditions affected wild blueberry production aw well as insect pressures.

We are seeing yield reduction by drought in the Parrsboro and Amherst areas. Colchester blueberry fields seemed to do fine but still below the expectation. Up to this point, we do not have the final number of total wild blueberry yields for this year yet, but we are expecting less than the anticipated 50 million lbs."

Hugh Lyu (Perennia Inc.)

New Brunswick

"Although exact weights are not yet available, early indications are that the 2020 crop is down significantly.  This is due to a combination of frost in the spring followed by summer drought conditions.  The season had good news with favorable fruit set but finished with less than optimal smaller and lighter berries."

Michel Melanson (NB DAAF) 

Once the final weights are available we will follow up with information on how this years crop compared exactly with previous years.

Are You a Shrewd or “Shrewed” Beekeeper?

Beekeepers know that honey bees need to be protected against opportunistic omnivores and insectivores.  Bears and skunks will hungrily enter our apiaries in search of a meal.  On the other end of the size scale, but none the less dangerous to honey bees, are the smallest mammals in our region: the shrew.  There are seven species of shrew found in eastern Canada.  One of these, the Maritime Shrew (Sorex maritimensis) is the only endemic mammal to our region.  Other species include the venomous Northern Short-tailed Shrew whose bite delivers deadly toxins!  Also, our region hosts the smallest of the shrews, the aptly named Pigmy Shrew.

A shrew found in a dead-out hive in spring.  Note the feces which differs from that of a mouse.  Without studying the dentition of this individual, it can only be stated, due to the size, that it is likely a Common Shrew (Sorex cinereus).

Dr. Donald McAlpine, Curator of Zoology in the Department of Natural History of the New Brunswick Museum, has extensive knowledge of and research experience with our region’s shrews.  He suggests that, when it comes to eating honey bees, the Common Shrew (Sorex cinereus) is the most likely culprit followed by the Smoky Shrew and possibly Short Tailed Shrew.  The Pigmy Shrew is uncommon and so less likely, although equally willing, to attack beehives.  The Maritime Shrew and the Eastern Water Shrew, due to their habitat and distribution, are unlikely to attack beehives.  He also notes that, aside from the easily identifiable Short Tailed Shrew, it is difficult to visually differentiate one species from another, especially with juvenile animals.

Table 1. Shrew species found in eastern Canada

Common Name	Binomen	Unique Characteristics	Hive invader
American Pigmy Shrew	Sorex hoyi	Smallest of our region’s shrews, scarce	Yes
Maritime Shrew	Sorex maritimensis	Endemic to our region	Unlikely
Common Shrew	Sorex cinereus	Most numerous and widespread	Yes
Northern Short-tailed Shrew	Blarina brevicauda	Venomous, largest of our region’s shrews	Possibly
Smokey Shrew	Sorex fumeus	Odorous	Yes
Long tailed Shrew	Sorex dispa	Uncommon	Unlikely
Eastern Water Shrew	Sorex albibarbis	Forages in water	No

Shrews have a very high metabolic rate and, unlike many small mammals, are not dormant or hibernating through the winter months.  The result is that these voracious insectivores will almost double their food intake to keep warm and active during winter.  For these reasons, beehives must be protected against shrews while the bees are clustered and most vulnerable!  The Chief Apiary Inspector for the province of New Brunswick, Fletcher Colpitts, feels that the shrew is a very common problem for overwintering honey bees in our region.  He has written an excellent fact sheet with further background information and suggestions of how to protect your hives during the winter.  You can access this factsheet on the New Brunswick Beekeepers Association website.

There are a couple of key points to consider when protecting your hives against shrews.  The Pigmy Shrew, although less common than the others, can fit through any space larger than 1cm.  Therefore, guards used to protect hives must have a screen opening size of no larger than 6mm.  Also, it must be noted that the small size of the screening will remove pollen from the bees as they enter the hive.  This may deprive them of important early spring nutrition.  This leads to Mr. Colpitts recommendation to put the screen in place in December and remove it prior to spring pollen foraging by the bees.

If you are a beekeeper concerned about shrews, make sure to subscribe to our blog.  We will be talking about shrews again soon and provide details of a study we are establishing with local researchers to determine the presence and species of shrew in individual apiaries.  Stay tuned for upcoming details and contact us if you want to ensure your place on this project.  More to follow!

Connecting with ATTTA Specialists

If you’d like to connect with ATTTA specialists or learn more about our program, you can:

visit our website at https://www.perennia.ca/portfolio-items/honey-bees/

Email abyers@perennia.ca


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