How to Winterize Bees: A Complete Winter Preparation Guide
Protect your colonies through winter — varroa treatment, feeding, insulation, ventilation, & wind protection until spring.
Winter kills more colonies than varroa mites, starvation, and disease combined. In many regions, 30–40% of colonies die each winter, and the difference between survival and loss comes down to preparation done months before the first frost. The good news: every major cause of winter death is preventable with the right steps at the right time.
What You Need
| Item | What It Does | Why You Need It | Recommended |
|---|---|---|---|
| Apivar strips | Synthetic miticide that kills varroa mites over 42 days | Mite-damaged colonies produce weak winter bees that die by January — treat BEFORE cold weather | $25 for 10-pack |
| Entrance reducer | Narrows hive entrance to ~⅜ inch | Keeps mice out (they nest in warm hives and destroy comb) and reduces cold drafts | $9.99 for 5-pack |
| Honey B Healthy | Essential oil feeding supplement | Added to 2:1 fall syrup to boost bee immunity and promote consumption | $34.50 for 16 oz |
| White table sugar | Makes 2:1 syrup (2 lb sugar : 1 lb water) or candy board filler | Emergency carbohydrate feed when honey stores are insufficient | Grocery store, ~$5/10 lb |
| Candy board feeder | Wooden frame holding hardened sugar candy above cluster | Emergency winter feed — bees can access it without breaking cluster | $22 |
| Quilt box or rigid foam board | Absorbs moisture from warm air rising off cluster | Prevents condensation dripping onto cluster — the #1 winter killer in mild climates | $35 |
| Bee smoker | Calms bees during inspections | Required for every inspection, including fall treatment checks | See smoker guide |
| Bee suit | Full-body protection | Fall bees are defensive — protect yourself during treatment inspections | See suit guide |
Why colonies die in winter
Understanding the four main causes helps you prevent each one:
Starvation (most common) — The colony runs out of food before spring nectar flow begins. In cold weather, the cluster can’t move sideways or down to reach honey stores just 2–3 inches away — they can only move upward as they consume the comb above them. A colony with honey on the sides but not directly above the cluster will starve even with 50+ pounds of stores in the box.
Moisture/condensation — Warm air (95°F) from the cluster rises and hits the cold inner cover. Condensation forms and rains back down onto the bees. Wet bees die from chilling at temperatures that dry bees survive easily. This is why beekeepers say “cold doesn’t kill bees — moisture does.” A colony can survive -40°F if it’s dry, but will die at 25°F if water drips on the cluster.
Varroa and viruses — High mite loads in fall produce weak winter bees with shortened lifespans. A healthy winter bee lives 4–5 months (October through February). A varroa-damaged winter bee may only live 4–6 weeks. By January, the colony has no adult bees left to maintain the cluster, and it collapses. See our varroa treatment guide for testing and treatment methods.
Queen failure — The queen dies in fall or stops laying too early (before winter bees are raised). Without the long-lived winter bee population, the colony dwindles through winter and dies. If you find no brood and no queen during your fall inspection, the colony is likely doomed — combine it with a stronger colony using the newspaper method.
Step-by-Step Winter Preparation
Step 1: Test and treat for varroa mites in late summer
This is the single most important winter preparation step. Do it in August or early September, after honey supers are removed.
First, test mite levels using a sugar shake or alcohol wash. Take 300 bees (about ½ cup from a brood frame), shake them in powdered sugar or alcohol, and count mites falling through a mesh screen. More than 3 mites per 100 bees (3% threshold) means immediate treatment is needed.
For treatment with brood still present, use Apivar strips — apply 2 strips per brood box for 42 days. Apivar is effective (95%+ mite kill) and works with brood because the active ingredient (amitraz) is absorbed through bees’ tarsi and distributed through the colony by trophallaxis (food sharing). Remove honey supers before applying — Apivar residues make honey unsalable.
If you prefer organic treatments, formic acid pads (MAQS) penetrate capped brood cells and kill mites hiding inside. They’re temperature-sensitive — apply when ambient temps are 60–85°F for best results.
Common mistake: treating without testing. Some beekeepers apply treatment every fall regardless of mite levels. This wastes money, selects for chemical resistance, and may kill beneficial microbes. Always test first — if mites are below 3%, skip treatment and retest in 2 weeks.
Timing matters: Treat too early (before supers are off) and your honey is contaminated. Treat too late (October) and the broodless period hasn’t started, making oxalic acid treatments less effective. The sweet spot: late August to mid-September in most US climates.
Step 2: Assess food stores and begin fall feeding
By late September, evaluate whether the colony has enough honey to survive winter. In most US climates (USDA zones 5–8), a colony needs 60–90 pounds of stored honey. In cold northern zones (3–4), plan for 80–120 pounds. In mild southern zones (9–10), 40–50 pounds is usually sufficient.
The simplest assessment method: heft the hive by lifting one side. An empty deep box weighs about 40 pounds; a full one weighs 80–90 pounds. If the hive feels light for its size, feed immediately.
How to feed: Mix 2:1 sugar syrup (2 pounds white granulated sugar dissolved in 1 pound of hot water by weight — that’s 4 quarts water to 8 pounds sugar). Use a top feeder or division board feeder inside the hive. Add Honey B Healthy Original at 1 teaspoon per quart of syrup — the lemongrass and spearmint essential oils stimulate feeding and may support immune function.
Feed until the colony stops taking syrup (usually 2–3 weeks). Then switch to solid feed: either a candy board placed above the inner cover, or dry sugar poured on newspaper directly above the cluster. Solid feed won’t freeze, and bees can access it without breaking the cluster.
Pro tip: In northern climates, place a candy board feeder above the inner cover in November as insurance, even if stores seem adequate. If the colony runs out of honey in January, the candy board is right above the cluster where they can reach it. Without it, you’d have to open the hive in freezing weather to emergency-feed — breaking the thermal seal can kill the cluster.
Step 3: Reduce the entrance and remove queen excluders
By late October, install an entrance reducer set to the smallest opening (about ⅜ inch). This serves two purposes: it prevents mice from entering the hive to nest (mice chew through comb and build nests that destroy frames), and it reduces cold air flowing into the lower brood box.
At the same time, remove any queen excluders from the hive. The queen excluder is a metal or plastic grid that prevents the queen from moving up into honey supers. In winter, if honey is stored above the excluder and the cluster needs to move upward to reach it, the excluder traps the queen below and the workers won’t abandon her to access food above. This has caused colonies to starve with 50+ pounds of honey just 2 inches above the cluster.
Also at this point, rearrange frames so honey is positioned directly above the cluster. Move full honey frames to the sides and upper boxes, and position the cluster (brood area) in the lower center. Bees move upward through winter as they consume stores — they won’t move sideways.
Common mistake: leaving the queen excluder on. Many beginners forget to remove it because it’s between boxes and easy to overlook during a quick fall inspection. Make it part of your winterization checklist and physically remove it every October.
Step 4: Add top insulation and upper ventilation
Insulate the top, not the sides. This is the most counterintuitive rule in winter beekeeping. Wrapping hives with insulation board or black tar paper (a common practice in the 1970s) traps moisture inside and often does more harm than good. Cold alone doesn’t kill bees — the cluster maintains its core temperature at 93°F regardless of outside temperature, even at -40°F. Moisture kills.
Place a quilt box filled with wood shavings or a sheet of rigid foam insulation board (1–2 inches of extruded polystyrene from any hardware store) on top of the inner cover. The insulation prevents the inner cover from reaching the dew point, stopping condensation before it forms.
At the same time, create a small upper ventilation opening — a shim (⅜ inch spacer) between the inner cover and the outer cover at the front edge. This lets warm moist air escape upward and out through the telescoping outer cover’s overhang. The opening should be small (about 1 inch wide × the width of the shim) — too much ventilation causes excessive heat loss, too little causes moisture buildup.
Why this combination works: The insulation keeps the inner cover warm enough to prevent condensation. The upper ventilation lets any residual moisture escape. The cluster stays warm and dry. This setup has been validated by university extensions in Minnesota, Vermont, and Ontario — regions where winter temperatures regularly drop below -20°F.
Common mistake: insulating the sides instead of the top. Black tar paper wrapped around hive bodies absorbs solar radiation during the day, causing temperature fluctuations that stress the cluster. It also traps moisture from the cluster’s respiration against the cold outer walls. If you want to wrap for wind protection, use a breathable material (burlap or landscape fabric) that allows moisture to escape.
Step 5: Final checks and wind protection
By mid-November, do your last hands-on inspection before winter closes the hive. This is your last chance to fix problems before spring:
- Check cluster position: Open the hive on a day when temperatures reach 50°F+. Confirm the cluster is in the lower brood box and honey frames are above and to the sides. If the cluster is already in the upper box (meaning they’ve moved up and abandoned lower stores), slide the upper box down and place honey above them.
- Confirm food position: Honey must be directly above the cluster. One frame of honey directly above the cluster is worth more than five frames on the side during cold weather. Rearrange frames accordingly.
- Check the outer cover: Ensure it fits tightly and the metal top isn’t rusted through (water leaking through the cover is as bad as condensation). Replace damaged covers before winter storms.
- Wind protection: In exposed locations, stack straw bales on the north and west sides of the hive to block prevailing winter winds. Don’t stack them against the hive — leave 6 inches of clearance for ventilation. In bear country, install an electric fence before bears begin foraging for winter food (typically October–November).
After these checks, close the hive and don’t open it again until temperatures reach 50°F+ in late winter or early spring. Opening the hive in cold weather breaks the cluster’s thermal seal. The warm air escapes, bees scramble to re-form the cluster, and the temperature shock can kill bees on the outer edge of the cluster.
Winter Monitoring Without Opening the Hive
Once prepared, monitor from the outside only:
- Weight — Heft (lift one side of) the hive monthly. If it feels noticeably lighter than October, add emergency feed: pour dry sugar on a sheet of newspaper placed on the top bars, directly above the cluster. The bees will climb up through a small hole in the newspaper to access the sugar without breaking cluster formation.
- Sound — Tap the side of the hive with your knuckles and put your ear against the wood. A soft, low hum means the cluster is alive and maintaining temperature. A loud buzzing sound can indicate robbing wasps. Silence is a warning sign — try again on a warmer day before concluding the colony is dead.
- Dead bees at the entrance — A few dead bees on the landing board each week is normal (winter mortality is ~10-15% of the population). A large pile of dead bees blocking the entrance is abnormal — it usually means a dead colony.
- Cleansing flights — On warm days (50°F+), bees should emerge briefly for defecation flights. If you see yellow streaks on the outside of the hive (bee feces), that’s normal after a long confinement. If no activity on a day when nearby hives are flying, something may be wrong.
Pro tip: Place a small piece of wire mesh (¼ inch hardware cloth) over the reduced entrance in early winter. This prevents dead bees from blocking the tiny entrance opening while still allowing bees to pass through. Blocked entrances have caused colony suffocation during extended cold spells.
Frequently Asked Questions
Q When should I start preparing my bees for winter?
Begin in late August to early September. The sequence matters: (1) remove honey supers, (2) test and treat varroa, (3) assess stores and begin feeding, (4) reduce entrance, (5) add top insulation. In colder climates (zones 3–5), complete all steps by late October. In milder climates (zones 8–10), you have until mid-November. The varroa treatment is the most time-sensitive step — it needs 42 days (Apivar) or 7 days (formic acid), so starting in August gives you time to complete treatment before cold weather arrives.
Q How much honey do bees need for winter?
In most US climates (USDA zones 5–8), a colony needs 60–90 pounds of stored honey. In cold northern zones (3–4), plan for 80–120 pounds. In mild southern zones (9–10), 40–50 pounds is usually sufficient. The best way to gauge is hefting — lift one side of the hive. A deep box full of honey weighs about 80 pounds. If the entire hive feels heavy (you can barely lift one side), stores are adequate. If it lifts easily, feed immediately with 2:1 syrup.
Q Should I wrap my hives for winter?
No — insulate the top, not the sides. Wrapping the sides with black tar paper or insulation traps moisture from the bees' respiration against the cold walls, causing condensation inside the hive. Cold doesn't kill bees; moisture does. A quilt box or rigid foam board on top of the inner cover prevents condensation at the ceiling. If you need wind protection, stack straw bales on the north and west sides — but don't wrap the hive body itself.
Q Do bees hibernate in winter?
No — bees don't hibernate. They form a winter cluster and vibrate their flight muscles to generate heat. The cluster contracts when it's cold (drawing tighter to conserve heat) and expands when it's warm (allowing bees to access food stores on outer frames). The core temperature stays at 93°F regardless of outside temperature. On warm days (50°F+), workers take short cleansing flights. A strong colony in a dry hive can survive -40°F outside temperatures.
Q What do I do if the colony runs out of food in mid-winter?
Don't open the hive in cold weather. Instead, make a small opening in the inner cover (or lift the telescoping outer cover briefly) and place dry sugar on a sheet of newspaper directly on the top bars above the cluster. Cut a small slit in the newspaper so bees can climb up to access the sugar. Alternatively, place a candy board above the inner cover — these are designed for exactly this scenario. If temperatures are above 45°F, you can quickly pour dry sugar directly on the top bars near the cluster. Emergency fondant (available at bakery supply stores) also works — press it against the top bars.
Q How do I know if my colony survived winter?
On the first warm day (50°F+), check for activity: bees flying in and out, bringing in pollen (a sign the queen is laying), and normal buzzing from inside. If you tap the hive and hear a healthy hum, open it briefly to check: is the queen present? Is there brood? Are there enough bees (should cover at least 4–5 frames)? If the colony is small but alive, consider combining it with another small colony — two weak colonies rarely survive spring, but one combined colony usually does.
Control mites before winter with our varroa treatment guide, and keep yourself protected during fall inspections with a quality bee suit and smoker. New to beekeeping? Start with our beginner’s guide.
Related: Spring Bee Management — recommended further reading.