Early Spring Inspections/Hive Necropsy

It’s early spring and the time of year in Minnesota where days start to get slightly warmer. I heard some new bird songs this morning and the sun feels just a little stronger shining over my shoulder. As I make my veterinary visits from farm to farm I keep having a similar conversation with folks. Everyone seems to agree, its that time of year where we can finally say we’re over with the better part of winter.

Which means, it’s time to go and check the bee yards!!

Colony Weight: There is always some apprehension, especially here in Minnesota where the winters make beekeeping especially challenging. If its still cool out, you won’t want to open colonies, but you can still make sure they’re alive. You can also check weight of each colony by doing a lift test. If you can easily lift one side of a bottom deep with one arm, chances are they are getting a bit light and will need sugar supplementation. If temps get into the 50’s, it’s warm enough to have a quick check into each box and see how much honey is left. They should have at least 3 frames in mid March to make it until early flowers start to bloom.

Sugar Supplementation: Right now (3/16/19) is still to cold for bees to be fed liquid feed, so if they need sugar, you can make your own paddies, or lay 1 sheet of newspaper over the top bars, then add loose sugar on top of the newspaper. The bees will be able to crawl up around the edges or chew through the paper to ingest the sugar.

Adding Frames of Honey: If you’d like to add frames of honey from a dead out colony to a colony that needs more food stores please be SURE that those bees didn’t die of a bacterial or fungal infection such as ABF, EFB or chalk brood as this can be passed in honey to your other hives. For this reason, it’s not recommended to feed honey to other colonies because of the risk of spreading disease.

Adding Protein Paddies: If you have several colonies who are at a good weight with plenty of left over food stores, you can also consider giving them a protein paddy. We want to start to stimulate brood rearing, but need to do it when warm weather is expected as we don’t want the brood to be killed in cold temps if the bees need to cluster. A healthy colony will stimulate brood rearing naturally from stored pollen sources as well as early spring flowers, so adding protein paddies is not necessary in all cases.

Sugar and protein paddies for the bees

Hive necropsy: Necropsy is the word veterinarians use when they perform an “autopsy” on an animal to figure out why it died. The same idea can be applied to dead out colonies as well. We want to know why they died so we can manage them differently and hopefully more effectively this coming season.

Based on survey’s done by the Bee Informed Partnership (www.beeinformed.org) in 2017/2018 hobby beekeepers lost 46.3% of colonies, while sideliners and commercial beekeepers lost 38.0% and 26.4% respectively. These are huge losses! If a dairy producer told me they’d lost 46% of their cows during the winter we’d have some serious management issues to address, not to mention ethical animal abuse considerations.

So let’s change these numbers beekeepers! Let’s strive to be as informed as possible and use best management strategies to combat the problems we know are out there.

There can be a lot of reasons for colony loss during winter. Starvation, poor ventilation and parasitism are high up there on the list, and all of these can be addressed with proper management. If you’d like help evaluating why you have a dead colony, please leave the colony undisturbed, and I’d be happy to come out and go through the colony with you to determine what we can change for future seasons.

Best wishes for happy, strong bees during this early spring weather!

Dr. Eva

Winter loss 5
Winter loss 7
Poor ventilation in a dead out colony





Winter Collaboration with UMN CVM

Well it’s back to that time of year where things are slowing down again. It’s nice to have this cyclical transition in my life and I’m thankful to both of my veterinary jobs for allowing me to have a little break during the winter (equine medicine and honey bee medicine take a little pause during the chillier months). Summer and even fall have flown by!!

I have a couple of updates on my hives. I transported them all back to my house in Northfield at the end of Sept/Oct where I’d be able to do a little supplemental feeding as needed. Mite counts where quite low at the end of August, and unfortunately, I didn’t check them diligently enough in September. By the end of October mite levels had risen and I treated all of my hives with oxalic acid dribble after there was no more brood. I placed sticky boards under 2 colonies and observed the mite drop. Wow!! Again, I wished I’d monitored them a little more in September as I’m a little concerned about the quality of the bees produced during that month due to mite predation. All hives did well at putting up honey and even my smallest colony continued to take some supplemental sugar into the middle of November. I increased ventilation with a moisture system and insulated each hive. I’ve checked them frequently through the ventilation hole with a stethoscope, and they appear to be doing well in their clusters. I’ll continue to check each colony throughout the winter.

Stethascope hive


In other exciting news, I was invited to give a presentation at the University of Minnesota College of Veterinary Medicine on honey bee medicine. It was quite an honor, and it was a wonderful opportunity to be able to pass on some of the knowledge I’ve gained to current veterinary students. I was impressed with the number of interested students who attended the lecture (about 70 in total). The lecture included the basics of honey bees from an anatomy/physiology standpoint, a little about diseases of honey bees and how to perform field evaluations of apiaries. I’m offering some limited field experience using my bees in the spring so students can come out and get familiar with handling bees.

If you’re reading this and would like to volunteer to have students out to your apiary, please send me an email and we can arrange something for the spring/early summer months if you live within an hour of the Metro.


I hope honey bee medicine continues to be an area of interest at the University of Minnesota College of Veterinary Medicine!! If we were able to establish a program, possibly in conjunction with the UMN Bee Lab it would be one of just a few within veterinary schools in the US and would help give our pollinators a helping hand. A win-win for students and ecosystem health!



Best Holiday Wishes,


Dr. Eva

Minnesota Hobby Beekeepers Association

I wanted to thank the Minnesota Hobby Beekeepers Association for inviting me to speak at their meeting last Tuesday 6/12. It was a pleasure to be able to speak about bee diseases from a veterinary perspective to such a well informed group. As promised I’m adding my presentation to the site. If anyone has questions about the presentation or about their bees let me know!

Don’t forget to inspect hives and do diagnostics this summer! Now is a good time to start doing regular varroa mite sampling!


Dr. Eva

Veterinary Perspective bee pp


It’s summer in Minnesota!! Funny that the last post commented on how cold it was in April, and now over Memorial Day, we’ve set some new record temperatures in the high 90’s to 100’s. But the exciting news that I’ve been wanting to share is the bees finally arrived!  They were installed in their new hive on Sunday morning. They looked great, with several good frames of brood, new eggs being laid and food frames with plenty of nectar and pollen to eat. They really wanted a new home as they’d made bur comb all over the top of the frames and inside the nuc box.  I briefly saw the queen as she came around the edge of a brood frame and I was really relived I’d seen her so I knew she wouldn’t get stuck when placing the frames in the hive. The bees are quite gentle and despite having their old home cut apart, they didn’t try to sting. I had to cut away all that extra comb to get the hive cover over the top. I’m sure they’ll be busy in there drawing out comb! I’ve been checking on the entrance several days in a row and they seem to be adjusting well. There are lots of bees coming with full pollen loads and quite a few at the entrance.

Even though I don’t own land and don’t have the means for a farm, this little hive of bees feels a little like livestock ownership. A small step in an important direction.

Here’s to the beginning of summer and many warm and sunny days to enjoy beekeeping!!

Dr. Eva Reinicke


Spring Updates

Hi Everyone!

It’s been a long winter (and spring) and a while since I’ve added to the blog so I’m going to share some personal updates. Winter here in MN went well this year if you enjoy winter. It was cold early, starting in mid-December, without any snow for a while. But by mid-January we had plenty of snow for skiing and the temps were getting down in the single and below zero digits. We had enough snow to keep me on skis for 52 days straight which is a new personal record for me!! I also skied the American Birkiebeiner for the 3rd time in almost perfect conditions. It’s always a blast and such a celebration of winter.

Birkie pic

In early March temperatures started to warm up and there were a few days of great crust skiing, but after that the corn and beans fields started emerging from the snow and the long rays of sun set to melting our winter playground. Then mid-April arrived, and now we’ve been plunged back into winter with 10-12 inches of new snow!

But temperatures are looking better and we’ve been promised 60 degrees by next week! I’ve been searching through seed catalogs for several days dreaming about green spring growth and trying to choose the perfect variety of tomatoes, lettuce and carrots among other things. I’ve also spent quite a bit of time looking over mixes of flower seed, cosmos, sunflowers, lavender, bee-balm, verbena and wildflowers, trying to find some that I can grow successfully near the shaded house.


I’m also the jubilant and apprehensive new owner of two hives (although bees have not arrived yet). Along with them I purchased a gallon feeder for each hive, which seems like they may get a lot of use this April with the lows in teens and twenties. I also got an expert craftsman to help me create hive stands. I’m really looking forward to putting them to use!


For those that have bees arriving in the next few weeks, make sure to keep a close eye on the temperatures!! Packages of bees are especially sensitive to cold weather because they don’t have previously stored food supplies. Consider bringing bees inside to a warm garage at night if it gets cold and make sure you have adequate ways to feed them.


If you overwintered bees here in Minnesota chances are you have already been out to check them and feed them as needed starting during the warm days in March. If you have any questions about dead out hives or want information about disease management give me a shout!

All in all it’s going to be a great growing season and I can’t wait to get started!

Dr. Eva Reinicke

Part 2

Winterizing Honey Bees

Weather here in Minnesota was unusually cold for the end of October and beginning of November with temps at night being down in the teens. But we reached an unusual high of 61 degrees yesterday in Northfield and the remaining part of the week looks like it will be in the 40’s and 50’s.

So now is the time to get out there and winterize your bee hives if you haven’t done so already! Here are some practical tips for consideration as we prepare for the long winter months.

Practical Recommendations for Overwintering Bees

1) Honey Bee Health: It’s important to acknowledge that all of the work and effort you put into managing your hives during the fall is going to pay off during the winter. Varroa mite checks and treatment, Nosema, foul brood and chalk brood checks, as well as queen vitality, brood nest size and drone culling are all vitally important management points to make sure you have a healthy colony going into winter. You should leave 75-95lbs of honey with each overwintering hive. Unfortunately, if you haven’t assessed these things up until now, late November is not the time to start as most treatments need to be done during warmer weather with an open hive.

2) Winter Nutrition: Nutrition plays a large role in how bee colonies respond to environmental conditions. Its important to allow them to go through natural physiologic cycles as day length decreases. Do not provide overwintering bees with pollen paddies, as this will encourage them to start brood rearing and use up valuable resources. Don’t be confused by many migratory bee keeps who move bees to warmer locations during the winter and want them to have productive brood during the fall. If you have determined your colony is weak or doesn’t have enough honey stores for the winter, sugar feeding is still appropriate late into fall/early winter.

3) Choosing a place to overwinter hives: Finding a good yard to overwinter hives can be important to their survival. You want to choose a place that is sheltered from the wind, but gets a fair amount of winter sun. It should be close enough for you to be able to check the bees regularly even if there is deep snow. It’s ideal to reduce vegetation and weeds around the hives to discourage varmints from moving into the area.

4) Wrapping Your Beehive: In really cold regions like Minnesota its beneficial to wrap your bee hive. There are quite a few suggested strategies for this and one point to always consider; there must be enough ventilation to reduce moisture build up.

Hives can be wrapped using a belt-wrap method where the supers are wrapped around and around until everything is covered. Then the material is staple to the hive. Don’t forget to open holes in the wrap over your ventilation hive holes. They can also be wrapped by a sleeve method, where the material is pre-measured, sewn or stabled together, then dressed over the top of the hive. A third method is to blanket multiple hives that are right next to each other with material, then staple it in place. Good materials to wrap a hive with include:

a. Waxed black cardboard commercial winter cartons

b. Black tar paper

c. Reflectix TM

d. Six-mil black plastic

e. Kodel®


Hives wrapped by belt method. (Photo credit Manitoba Beekeeping http://mbbeekeeping.com/)

5) Ventilation: Bees are living organisms and because they warm the hive throughout the winter they produce a lot of water. The hive should have an entrance hole in the bottom, as well as a ventilation hole in the top super right below the handle. Make sure that the hive wrap you have placed has a hole in it to allow ventilation.



Ventilation hole. (Photo credit to UMN Bee Lab)

6)Moisture Boards: These are important to control moisture build-up in the colony. They are placed inside the inner cover and should be made of a porous material that collects moist ure. Sheet insulation is not a good idea because it doesn’t absorb moisture and can cause water to drip onto the cluster. Good materials to make moisture boards include:

a. 3/4” Bild Rite® sheeting

b. Shag carpet

c. 1’’ stack of newspaper

moisture board

Here is an example of a moisture board. (Photo credit to UMN Bee Lab)

Those are at least the basics of tending overwintering honey bees. For now I’m going to head outside and try to enjoy some of this last minute warm weather. Although secretly I’m hoping for lots snow so cross country skiing can get underway!!

As always, thanks for reading and enjoy.


Eva Reinicke DVM



Doke, M. A., Frazier, Maryann, Grozinger, Christina M. Overwintering honey bees: biology and management. Current Opinion in Insect Science. 2015, 10:185-193

Reuter, Gary S., Spivak, Marla. Wrapping Honey Bee Colony for a Northern Winter. University of Minnesota Instructional Poster #163.1, Department of Entomology.

Watson, Eliese. Winterization Guide for Beekeeping. Apiaries and Bees for Communities. http://www.backyardbees.ca

Hives in snow

Wintering Hives

Winterizing Hives to Prevent Disease

We’ve been experiencing some chillier weather here in Northfield, MN the last couple of days. It was down in the 40’s as a daytime high and there were several mornings with a mild frost. Between now and mid-November is the time to start winterizing bee hives to prevent disease and starvation during colder months. Before we discuss how to winterize a hive to maximize survival, we should understand the physiology and behavior that allows bees to survive a cold winter. This will be Part 1 of a two-part series on winterizing honey bees. Part 2 will be a practical recommendation on preparing hives for cold weather.

Part 1

Hive Physiology and Behavior

Bee colonies work within a yearly cycle where their behavior and physiology changes to meet the season. During the spring and summer individual bees live shorter lives, about 30 days, and all bees in the colony have specific roles that change as they age. After hatching they become nurse bees and tend brood, middle aged bees build wax, undertake and protect the colony and older bees forage for nectar and pollen. Each bee spends about 10 days in each role.

During winter months bees can live up to 240 days and they all contribute to forming a thermoregulatory cluster that keeps the colony warm and fed. During the fall “winter bees” hatch from the colony and the bees have a distinctly different physiology compared with their summer counterparts. Winter bees have increased amounts of a protein called vitellogenin, and increased hemolymph proteins, while they have a decreased amount of juvenile hormone (foraging bees have a very high amount of JH) and larger hypopharyngeal glands. It’s thought that these physiologic changes make it possible for winter bees to remain in the “nurse bee” stage which slows aging throughout the winter. Bees also rely on hormones to communicate throughout the seasons. During the winter there is little brood rearing so brood hormones don’t trigger bees to age to middle or forager status. Foraging bees also remain in the hive during the fall and release a hormone called ethyl oleate which slows down young bee maturation (Doke).

During cold months bees come together and shiver to create a thermoregulatory cluster. They use wing muscles to move air molecules and create heat, keeping it warm inside the hive. This behavior starts when air temperatures dip down below 50 degrees. The center of these clusters can be up to 95 degrees F and 40 degrees F on the outside even during the coldest parts of the winter. During honey consumption bees also produce water as a metabolic waste and the hive can become quite humid even though temperatures are below freezing outside. The bees drink the water, but it can also form dangerous condensation on the roof of the hive(Watson). The cluster of bees generally starts in the brood frames at the bottom of the hive, then moves upward into the honey supers as food is consumed throughout the winter.

There are many factors that signal to bees when to transition into winter and when to transition out again. Many of these factors have not been fully studied, but especially important among them is access to pollen, a major protein source. Colonies fed pollen at inappropriate times of the year will start to make brood and this can be detrimental to the survival of the colony. Other factors that trigger transition are presence or absence of brood, photoperiod, temperature and restriction to foraging material. There is still a lot of ongoing research in regards to successfully overwintering bees and understanding their physiology, nutritional and behavior needs.

Please stay tuned for the next post on practical recommendations for overwintering bees!

Thanks for reading and following the blog!

Dr. Eva Reinicke



Doke, M. A., Frazier, Maryann, Grozinger, Christina M. Overwintering honey bees: biology and management. Current Opinion in Insect Science. 2015, 10:185-193

Reuter, Gary S., Spivak, Marla. Wrapping Honey Bee Colony for a Northern Winter. University of Minnesota Instructional Poster #163.1, Department of Entomology.

Watson, Eliese. Winterization Guide for Beekeeping. Apiaries and Bees for Communities. http://www.backyardbees.ca

Goldenrod Bloom

The goldenrod appears to be blooming in full force here in Northfield, MN this week. It makes for a beautiful site along the road side ditches and in old pastures. Goldenrod is commonly mistaken as a weed of abandoned fields that have not been mowed in several years, but it is an extremely important food source for honey bees. It’s the last true bloom of the late summer/autumn season and many hives rely on the rich pollen and nectar of goldenrod to make it through the winter.

Goldenrod does not always make tasty honey (it tends to be a little bitter), so many beekeepers will remove their honey supers before the bloom, do colony inspections and then allow the bees to keep the honey produced during the autumn goldenrod harvest.

If you are out and about on the Minnesota byways in the next couple of weeks, take time to stop on the roadside near a stand of goldenrod and observe the busy harvest. It’s important to take a moment of appreciation for these late summer days with perfect splashes of sunshine.

Dr. Eva Reinicke

goldenrod with gate

Fall Verroa Mite Inspections

August is the time of year many beekeepers start thinking about managing colonies to set up for the long winters in Minnesota and Wisconsin. One of the most important aspects to this is making sure that they have a good Integrated Pest Management Plan (IPMP) for the colony so it is strong and disease/parasite free going into the winter.

The varroa mite is an external parasite of adult bees and brood that weakens colonies progressively throughout winter months. It sucks the hemolymph (similar to blood) of bees and weakens bees making them more susceptible to disease, decreasing lifespan and sometimes killing bees outright. A good IPM strategy is to monitor each colony (or for large apiaries 12-15% of their hives) for mites before treatment is considered. If the bees are relatively mite free i.e. below threshold, you may not need treatment. However, its important to remember with long winters in the North, even a low threshold of mites could mean problems. It’s important to remember treatment needs to be started by early September so bees have enough time to hatch brood and make honey for winter from the late autumn bloom.

There are many great tutorials on how to test your hive for the presence of the varroa mite. I’ve included instructions in the links below:

Sugar Roll Method  from the University of Michigan

Sugar Roll Method from the University of Minnesota

If you have questions, need more information or want assistance in an Integrated Pest Management Plan, please don’t hesitate to contact us!

Dr. Eva Reinicke