Hive Forensics

Or maybe better titled – “What in the World Happened to My Hive?”

What is a Dead Out?

A dead out is the name given to a colony that’s dead! That seems a little too simplistic, right? Not really. It actually implies a question rather than a definitive answer.

If I say I had three dead outs in my bee yard, don’t I want to know why? Of course I do. If I say a colony died from _____, you might think, “OK, that’s easy—just don’t do ____ again or do ____ and it won’t happen!” If only it were that easy.

The following is a broad overview of conditions and causes most commonly found in backyard beekeeper dead outs. Some of these conditions are seasonal, but many can occur any time of year.

Hive Condition: Dead bees head down in cells and/or a group of dead bees clustered around what “was” brood but has long since died.

Cause of Death: Starvation– The bees simply ran out of resources to eat. This can happen any time of year, but primarily at the end of Winter and early Spring (March.)

Hive Conditions and Possible Causes of Death

Hive Condition: Dead bees head down in cells, or a group clustered around what “was” brood but has long since died.
Cause of Death: Starvation – The bees simply ran out of food. This can happen any time of year, but primarily at the end of winter and early spring (March).

Hive Condition: Dead bees with no evidence of old brood
Cause of Death: Failing queen in late fall/early winter. If your queen wasn’t laying sufficiently in late fall, you lacked the workforce to stock up on resources, warm the hive, feed larvae, and groom and feed her. In spring, summer, and fall, a colony with a failing queen will quickly die—no eggs = no nurse bees = no foragers = no food!

Another Cause: Varroa mites – High mite loads can and will cause your colony to die. Signs are often gone by the time you find the dead out. Testing and treating for Varroa is crucial for survival all year, every year.

Photo credit: Annalisa Mazzarella

Hive Condition: Few bees milling around; may or may not have a queen present. Overpowering fermented odor and little “worms” (not maggots - larval form of SHB) in cells.
Cause of Death: Small Hive Beetle (SHB) infestation.
SHBs are common but, if uncontrolled, can cause colonies to abscond or die a slow, miserable death. Controlling SHBs is one of the easiest tasks in beekeeping—no testing or chemicals required.

Hive Condition: Few or no bees; “worms” (wax moth larvae) and moths crawling around, cocoons and webbing on frames.
Cause of Death: Wax moths due to neglect.
Wax moths are opportunistic. If allowed to take over declining colonies, they can destroy old comb, frames, and boxes. Address the problem immediately, or break down the box and store the equipment for future use. A neglected dead out will quickly turn to trash.

Photo credit: Dodie Stillman

“The problem starts when we don’t react to a situation, then a month later we face the reality that our colony didn’t recover without our intervention.”

Hive Condition: Some dead bees, or no dead bees, and no resources.
Cause of Death: Robbing – Ragged honey/nectar cell rims and wax debris on the bottom board indicate the colony was robbed rather than starved. This usually happens to weak colonies suffering from disease, virus, or failing queens.

Another Cause: Queen failure – The queen stops laying. Without new brood, the colony quickly collapses: no nurse bees, no foragers, no food, no wax building, no nectar ripening, no guarding bees.

Drone-Laying Queen: Excess dead drone brood cells (capped or not) may indicate the queen ran out of sperm. The colony cannot replace her, and collapse is inevitable.

Another possibility: Absconding – Sick, failing, or mite-heavy colonies may simply leave. Bees may not survive long once they've left, but staying in poor conditions is worse.

Photo credit: Bee Informed Partnership

Hive Condition: Some bees milling around, queen gone, no brood or unhealthy brood, maybe extra nectar but no nurse bees.
Cause of Death: Possible disease or virus – Evidence is often gone by the time the dead out is found. Note: Most viruses and diseases are preventable by controlling Varroa mites.

Another Cause: Swarming – Swarming can kill a colony if the daughter queen is not viable or fails to return from mating. The remaining colony often cannot sustain itself.

Hive Condition: Dead bees on the bottom board, moist and rotting.
Cause of Death: Moisture – Poor winter ventilation can lead to condensation dripping on the hive and mold and mildew. Colonies may abscond if unresolved.

Hive Condition: Dead bees inside the box, on the bottom board, or on the landing.
Cause of Death: Possible pesticide poisoning – A bee with its tongue sticking out and wings spread wide are key indicators. Poison may act slowly or be carried into the colony, causing the hive to ultimately die.

The Bottom Line

Hive forensics can be complex, but the key is simple: do regular inspections and stay on top of your bees’ health. Bi-weekly and quarterly checks help you catch problems before it’s too late.

Education is the best gift you can give your bees. Attend club meetings, seminars, webinars, and in-person classes. The reward of keeping healthy, thriving bees far exceeds the cost of time and money.

Happy Beekeeping!