One thing that we know for sure about beekeeping is that it's not an exact science. There are many factors and variables that go into keeping a hive alive and healthy. Wintertime is an extra hard time for honeybees especially if they live in colder, wetter northern climates. If your bees didn't survive the winter, here's a list of top reasons why they might have died:

  1. Varroa Mites
  2. Moisture/Condensation in the Hive
  3. Too Weak Going into Winter
  4. Blocked Entrance
  5. Starvation
  6. Yellow Jackets
  7. Absconding Due to Irritants
  8. Pesticides, Herbicides or Other Toxins
  9. Other Diseases - Nosema, AFB, Chalkbrood

Being a Detective

In order to determine the reason why your bees died, you have to become a detective. Here's what to do:

  1. Observe the Hive Surface: Check the surface and the area around the hive and make note of any bad or unexpected smells. Are there dead bees, a complete absence of bees or a disturbance around the hive?
  2. Remove the Outer Cover: Make note of anything under the outer cover, such as mold, moisture or something other than bees living there.
  3. Remove the Inner Cover: Observe anything unusual on the inner cover and the top bars of the frames. Look down through the frames to make note of a cluster, if there is one, but don't remove the frames yet.
  4. Remove the Hive Boxes: Remove them one at a time and carefully set them aside. You will examine the bottom board first. The condition of the dead bees on the bottom board, their age and location is very informative.
  5. Inspect the Lowest Box: Return to the hive body that was the one resting on the bottom board. Begin working through the frames and then continue on up through subsequent hive bodies to the top box.

As you move throughout the hive, ask yourself these questions:

*Where is the location of the main cluster?
*Where was the food located on the frames, in relation to the location of the cluster?
*Did you find a queen?
*Were there young bees or older bees clinging to the frames?
*Were the dead bees piled under the cluster or were they lining the entrance to the hive at the front of the bottom board?
*Did you find any brood? Was the brood capped?
*When you examined the frames, what did you find in the cells?
*Do the bees have deformed wings?
*Were there signs of robbing - chewed, ragged edges to cells or signs of other critters such as mice?

After you have inspected your hive and made notes on the questions above, you can use the following clues to help determine what might have caused the die out:

Mite Clues:

  1. Mite Clues If there are very few dead bees in your hive, it may mean the colony worked hard at removing them until the last minute. Try to find some dead bees on the bottom board or even on the ground nearby. Sift through them and look for bees with deformed wings. The presence of many deformed wings is a good indicator of Varroa.
  2. If you have a bottom board or Varroa tray in place, look for mites. If the colony died from mites, you will find mites in the debris.
  3. Look for frames of honey. A hive with plenty of honey and no bees can be a sign of Varroa. A hive with no bees and honeycomb with jagged edges indicates a weak or dead hive that was invaded by robbers, which can also be a sign of Varroa.
  4. Examine the brood frames. Adult bees that died while emerging, or just before, may have been weakened by Varroa. These bees will have their heads facing up (bees that starved while searching for food in the cells will have their tail ends up).
  5. Hold up the empty brood frames with the sun at your back so you can see inside the cells. If you find bright white deposits adhering to the inside of brood cells, you can be sure of a Varroa infestation. These white spots are patches of white excrement that contain about 95% pure guanine, an amino acid.

Moisture & Prevention:

Moisture CluesWet, cold bees are dead bees. New beekeepers may find mold in the hive and conclude that it was what caused the loss of the colony. Don't let this confuse you. You will rarely find mold in a healthy colony and the mold normally appears after the colony has died. Moisture in the hive is not a good thing. Disease organisms, fungi, and mold thrive in moist environments. In cold weather, water droplets can drip down on the bees and chill the brood. Proper ventilation is important for bee colonies year round. Bees can do really well in cold temperatures, but cold and wet is a different story.

*Tilt hive forward 1 inch
*Add moisture box
*Use a screened bottom board

Cluster Too Small Going into Winter

When the cluster of bees is too small going into to the colder winter months, a dead out will occur due to them not being able to create enough warmth needed to survive.

*Combine weak hives inf all with stronger, healthy hives
*Know your mite count even on weak hives
*Feed pollen patties in fall to make "fat bees"

Read part two of the series here.