When to Winterize Your Beehives

When to Winterize Your Beehives in Southeast Wisconsin and Northern Illinois

As the golden days of late summer fade and cooler nights settle in, it’s time for beekeepers in Southeast Wisconsin and Northern Illinois to shift their focus from honey harvesting to hive health and winter preparation. We've gotten a several questions from local beekeepers and new-bees about when to start prepping their hives or if they should be wrapping hives now. In this region, timing is critical—too early and you risk stressing your bees; too late and they may not survive the first cold snap.

When to Start Winterizing

Mid to Late September through Mid-October is typically the optimal window for winter prep in this region. By this time:

• The summer nectar flow has ended.

• Queens are laying fewer eggs.

• Mites may be peaking.

• The weather is still mild enough for bees to rearrange stores and access feed, but cool enough to begin insulation and protection.

Pay attention to overnight temperatures dipping below 50°F consistently—this is your signal to complete major winterization tasks.

Key Winterization Tasks

1. Assess and Manage Varroa Mites

Treat for varroa mites no later than early September using your preferred method (oxalic acid, Apiguard, Formic Pro, etc.). High mite loads heading into winter are the #1 cause of hive loss in the Midwest.

2. Ensure Adequate Food Stores

Your bees should have at least 60–80 pounds of honey or sugar syrup stored. In light hives:

• Feed 2:1 sugar syrup starting in late August.

• Use fondant or sugar bricks in late fall or mid-winter as emergency feed.

3. Check for a Healthy Queen

A strong, laying queen is essential to overwinter survival. If you suspect a failing queen, re-queening in early fall is possible—but time is limited.

4. Consolidate & Reduce Hive Size

Remove empty boxes, combine weak hives with strong ones, and reduce entrances to protect from drafts and pests.

5. Add Ventilation & Moisture Control

Use a quilt box, ventilated inner cover, or moisture board to prevent condensation buildup, which can drip on bees and freeze them.

6. Insulate Strategically

Wrap hives with breathable insulation like tar paper or commercial bee wraps. Use a foam board under the outer cover to reduce heat loss, but make sure the hive can still ventilate.

7. Protect from Wind and Critters

Place a windbreak to shield from prevailing northwest winds. Use entrance reducers or mouse guards to keep rodents out.

Local Considerations

In Southeast Wisconsin and Northern Illinois, winters are long, with sustained sub-freezing temps and heavy snow. It's not uncommon for bees to be clustered for 3–4 months without a cleansing flight. This means:

• Ventilation is essential.

• Mouse guards are a must.

• Emergency feeding may be necessary in late winter.

Final Winter Prep Checklist

•  Varroa mite treatment completed

•  60–80 lbs of honey/syrup stored

•  Healthy queen verified

•  Weak hives combined or removed

•  Hive entrances reduced

•  Insulation and moisture control in place

•  Windbreaks and critter protection added

•  Emergency feed (fondant/sugar bricks) ready

Final Buzz

Wintering bees in the Midwest is as much about preparation as it is about patience. A little attention now means a stronger colony come spring. If you're a new beekeeper, don’t be afraid to reach out to local clubs or mentors—we’re all in this (cold) together!