Improve hive ventilation

Reduce moisture inside the hive by improving airflow, since the chalkbrood fungus (Ascosphaera apis) thrives in cool, damp conditions. Install a screened bottom board to allow air circulation from below, and drill a small upper entrance (about 25 mm / 1 inch) near the top of the hive body to promote cross-ventilation. Tilt hives slightly forward so rain and condensation drain out rather than pooling inside.

Why It Works

Chalkbrood spores germinate most readily when brood comb temperature drops and humidity rises. Improved ventilation keeps the interior drier and helps bees maintain stable brood nest temperatures, making conditions inhospitable for fungal growth.

Tips

• Use a screened bottom board with a removable tray so you can monitor mite drops and debris while maintaining airflow
• Drill upper entrances on the side sheltered from prevailing winds to avoid excessive drafts
• Avoid wrapping hives too tightly in winter; allow some ventilation even in cold weather
• Remove any chalkbrood mummies from the bottom board regularly to reduce spore load