Fall Preparation for Beehives in Temperate Climates
by Dr. Carol Fassbinder-Orth
Why is it important to check your hives before winter?
Winter is a difficult time for animals- bees included! For honey bees, they stop raising brood around October in the Midwest and don’t start up again until about March. That means that the bees that are alive in October have to make it through the extreme cold for about 5 months otherwise the whole colony dies. Due to this stress, wintertime is usually when beekeepers see the majority of the annual losses. Therefore, we have put together some preparation tips for novice beekeepers to consider when preparing their colonies for the arrival of Jack Frost.
Part I: Food Storage
In an ideal world, honey bees would always be able to gather all the nectar and pollen they need, when they need it, and store enough excess honey to make beekeepers happy and have enough honey left over to survive through the winter. The unfortunate reality is that many beekeepers across the US (and globally) are losing about 1/2 of their hives each year. This means that beekeepers have to split up existing hives to make new ones, and hive size can vary drastically thoughout the year. This is why it is essential to check your honey and pollen stores of your hives throughout the year, but it is life of death to check these stores in the mid-fall.
Tip 1: Winter stores must be sufficient by the end of the last nectar flow.
In southern Iowa and Nebraska,honey is no longer collected after the beginning to middle of October, depending on seasonal temperature and the strength of the goldenrod flow. Bees need heat to evaporate water from nectar as they cure it into honey. They must store enough honey to get them through the winter BEFORE frost stops them from being
able to cure nectar or sugar syrup. You must evaluate hive stores, starting in mid-September, and anticipate any need to supplement hives with feed before frost shuts down the season. A small (nuc) hive should have at least 50 lbs of honey, and a full sized colony should have at least 80 lbs of honey.
Tip 2: Feed your bees an alternative sugar if they are too light in weight.
If you must feed them to achieve the necessary sugar stores, use cane sugar dissolved in water at a 2.25:1 ratio of sugar: water, or high fructose corn syrup. Do not give 1:1 mixture in the fall, as the bees must work to evaporate moisture from the syrup and this becomes a harder as the temperature cools. In our experience, high fructose corn syrup has the easiest consistency for feeding to bees and stores well in the hive.
Tip 3: Be prepared to check your hives in late February or early March for feed needs.
If they are running out of food, you should feed them with a supplement such as fondant, granular sugar, or frames of
stored honey. In early March, it may be possible to feed bees with high fructose corn syrup if you place the buckets under insulation wraps, as the bees may be starting to produce brood and the higher hive temperatures may promote consumption of the syrup. Make inspections brief during the winter months as removing the outer cover for any length of time is stressful to the bees.
The winter of 2018-2019 was long and cold. By my birthday in early March, the snow had still not subsided and the bees were getting hungry. We had to supplementally feed the bees with high fructose corn syrup to get them through the last bit of winter. Here is Carol pulling buckets of syrup on a sled back to a beeyard.
Part II: Honey Bee Disease Control
Many common pests and diseases, of honey bee colonies, such as wax moths, small hive beetles, ants,
chalkbrood, and European foulbrood will not thrive in a strong colony and are usually symptoms of a weak,
small or other-wise stressed colony. Colonies may be stressed by poor weather conditions, poor forage, or
heavy varroa mite infestations. Even infections with Nosema, a gut microsporidia, can often be cleared by a
healthy colony, or by replacing the queen (done in the spring).
One pest that you will not escape, no matter how hard you try (unless you live in New Zealand) is Varroa mites. Varroa mites (Varroa destructor) are currently the most devastating parasite for honey bees in the United
States. This parasite was introduced to the country in the 1980’s, and uncontrolled mite infestations are consistently found to be the primary factor underlying winter colony losses in scientific studies and surveys.
Varroa mites reproduce in the brood of bees and transmit deadly viruses to honey bees. Mite numbers rise and fall proportionally to bee numbers, however they are phase-‐shifted, meaning that mite numbers are rising in August as bee numbers are starting to decline. This corresponds to a high mite:bee ratio in the fall when the colony begins to cluster, and an increased rate of parasitism and disease transmission. If you don’t treat for mites, it is fairly safe to say that you will lose your colony within 2 years. There has been some progress made with queen breeding programs that focus on hygienic behavior that has been shown to reduce mite load. However, even those colonies usually require some level of mite control, and those experimental breeds make up a fraction of the available queens in the US.
Tip 4: Treat for Varroa mites at least twice per year to keep your colonies alive.
Treating bees for the first time in October is already too late. Ideally, one would treat in the spring prior to the first super being applied to the colony and again in August. Re-check mite levels in late September and if the numbers are still high, you can treat a second time using a different miticide(such as oxalic acid dribble, suitable for late season/minimal brood treatment) before packing your hives for winter. Be sure to use miticides responsibly. Some cannot be used when temperatures are too hot (or too cold). Others cannot be used when honey is still on the hive. Mann Lake has a good table that compares the currently available miticides here
Part III: Winterizing your hives: Ventilation and Insulation
Ventilation and Insulation
Ventilation is critical to survival of overwintering bees. Like all animals, bees produce carbon dioxide and water vapor as they metabolize food and respire in the colony. Although carbon dioxide buildup is usually not a problem, water vapor can quickly condense on cold surfaces and drip onto the cold bee cluster. Bees are not very resistant to dripping water, and will quickly perish in a wet environment. To avoid condensation, proper ventilation must be provided for the colony. This is often achieved by having both a small hole for an upper entrance in addition to their traditional slot for the lower entrance. Make sure that the bottom entrance to the hive remains open during the winter.
Tip 5: Make sure the hive entrances are clear throughout the winter to ensure proper ventilation and to prevent water buildup inside the hive.
Bees have limited food stores and metabolic capacity during the winter months. Extreme cold stresses their ability to maintain a viable temperature within their hive cluster. Just like our own houses, it is important to insulate beehives in the winter to prevent drafts and extreme cold from chilling the center of the hive cluster and killing the bees. Like your house,having exterior walls and an upper attic-like space with a high R-value will prevent heat loss from the colony. Some ideas for insulating your hives include: straw bales, rigid Styrofoam insulation (especially for the lids), black cardboard wraps, fiberglass encased in black plastic, and concrete curing blankets. Be sure to keep ventilation adequate, regardless of the insulation method chosen.
A thick blanket of snow blocks the main entrance of the hives in late February, 2019
Clearing snow from the front entrances prevents condensation and eventual suffocation of bees that can occur if entrances are completely blocked. Adding in upper exit holes (as shown here) is also an insurance policy in the event of high snow that cannot be cleared from the hives in the timely manner
Tip 6: Insulate your colonies before the first snowflake flies. We live in USDA zone 5. Our winterizing method involves placing a 1-2 inch rigid styrofoam board on the top of each colony, nudging four colonies together, and insulating the pack of 4 with an insulated black concrete curing blanket. This has been an easy, economical, sustainable, and successful method for our colonies.
Bees all wrapped up by mid-November in southwest Iowa