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Diagnosing Hive Death

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 so many of them could be in any season throughout the year.

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.)

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 the later Fall months, you lacked the workforce to stock up on resources, warm the hive during cold weather, feed larvae, as well as groom and feed her. In Spring, Summer & Fall – the colony will quickly die with a failing queen simply because of no eggs being laid; no eggs = no nurse bees = no foragers = no food!

Condition: Few bees milling around; may or may not still have a queen present along with an overwhelming bad fermented odor as well as little “worms” (looks like maggots) crawling in and around the cells. Cause of Death: Small Hive Beetle infestation. Small Hive Beetles are a part of our everyday beekeeping life, but when not controlled they can and WILL cause your colony to abscond (leave) or die a slow miserable death. Staying on top of SHB is truly one of the easiest tasks we face. It doesn’t require any testing and all effective methods of control are mechanical and don’t require medication or pesticides in the hive.

Expert: Chris Moore

Expert: Ed Erwin

Condition: Few bees or no bees; “worms” and moths crawling around, cocoons and webbing built on the tops, sides, and faces of frames. Cause of Death: Hive died and wax moths moved in. Wax Moths are opportunistic – they will completely destroy old comb and even eat into frames and the boxes. The nasty webbing mess is completely preventable. When you have a colony in decline, ideally address the problem immediately. If it’s obvious the colony isn’t going to make it, break the box down and store (freeze) the equipment for future use. A dead out left in your bee yard will quickly turn into trash if not addressed.

Condition: Some dead bees or no dead bees and no resources. Cause of Death: Robbing– If the rims of the resource cells (honey/nectar) appear ragged or torn and you find wax debris on or below the bottom board, the colony probably didn’t die of starvation but instead was robbed of all of its resources. This most often doesn’t happen to “strong colonies” but rather colonies with reduced populations due to virus, diseases or failing queens (causing decreased population.) Cause of Death #2 could be: Queen failed– The queen was present but stopped laying – left unnoticed, the colony was doomed. With no new brood, no new nurse bees to clean cells, warm the brood nest, feed larvae, feed and groom the queen, build wax, ripen nectar or guard the entrance. In turn no bees aging into foragers to bring in resources for the colony to survive. Given these conditions, the colony ultimately dies. Cause of Death #3 could be: Absconding (the colony left) Often when colonies are sick and failing, starving or have high mite loads, they will just leave! Would you live where the conditions are so bad you can’t stand to stay? Odds are those bees didn’t survive long once they left but they really didn’t have a choice…die if we stay, die if we go.

Condition: Some bees still milling around but Queen long gone, no brood or bad/sick looking (white, black, shriveled) dead brood, possible overabundance of nectar but no nurse bees present Cause of Death: Possible disease or virus present– When a colony dies from disease it can be very difficult to pinpoint the cause. Your “evidence” is most likely gone by the time you find the dead out. For a very good reference guide for identifying diseases CLICK HERE. Note: Most viruses and diseases are preventable by controlling Varroa Mites. To learn more about Varroa Mites and how to stay ahead of them CLICK HERE. Cause of Death #2 could be: Swarming - Yes, swarming can cause death of a colony! When a colony prepares to swarm, “in theory” they will create a viable queen cell (Daughter Queen.) Depending on how many swarm cells were produced and how well they were fed has a huge bearing on the viability of the “queen left to take over!” OR – the daughter queen left unmated and never returned, leaving the remainder of the colony that didn’t swarm to fend for themselves, often with bad results.

Condition: Dead Bees on the bottom board (moist and rotting) Cause of Death: Moisture– If the colony didn’t have sufficient ventilation in Winter, condensation can occur. Water vapor rises and as it condenses and chills it will then drip back down on to the bees and cause them to chill/freeze. Mold and mildew can also a problem with an overabundance of moisture. It won’t likely kill the bees but makes for a very poor environment for your colony and they will often abscond if left unresolved.

Condition: Dead Bees inside the box, on the bottom board, on the landing and on the ground in front of the hive. Cause of Death: Possible insecticide, herbicide, or pesticide poisoning. An indicator that bees have been exposed to poison is seeing bees dead with their tongues sticking out. Sometimes a kill can be over a period of time if the bees foraged in an area recently sprayed. In this case, the forgers may die off slowly and/or carry the poison into the colony causing a rapid kill.

It's not easy to determine how your hive died. The best defense we have as beekeepers is to do regular hive inspections in the warmer months and hive checks throughout the cooler ones.    

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