Ölü Koloni Otopsisi

A dead colony autopsy is the systematic examination of a hive that failed to survive the winter or the season in order to find the cause of death. The position of the dead bees, the location of the honey, the brood area and the debris on the floor often show the cause clearly. This knowledge saves the following year; emptying the hive and moving on means repeating the same mistake.

Why do a dead colony autopsy?

Most winter losses are decided months before death, in late summer and autumn: mite load, winter stores, the condition of the queen, damp in the hive. The hive preserves these traces for a while, but as time passes wax moths, mice and robber bees spoil the picture. That is why a dead hive should be examined on the day it is noticed, without disturbing anything.

The second purpose of an autopsy is to prevent the spread of infection. There is often a temptation to give the combs and honey from a dead hive to other colonies. If the cause of death was foulbrood, these combs will carry the disease through the whole apiary. No comb goes into another hive until the cause has been established.

How do you examine a dead hive? (step by step)

1. Close the hive first. Close the entrance immediately; a dead hive left open will be robbed within a few hours and whatever agent is inside will be carried to neighbouring colonies.
2. Record the outside. Dead bees in front of the entrance, faecal staining, gnawing marks, the tilt of the hive and the state of the roof. Take photos.
3. Open the roof and check for smell and damp. Note wetness, mould, dripping water, a sharp mouse smell or a smell of rot.
4. Locate the cluster. On which frames are the dead bees, how big is the cluster (a handful, or two frames' worth), is the cluster in contact with honey?
5. Measure the stores. Is there capped honey and pollen, and if so how many frames away from the cluster?
6. Examine the brood area. Dead larvae and pupae, perforated or sunken cappings, drone brood in worker cells, more than one egg per cell.
7. Look at the floor. Mites, heaps of dead bees, capping debris, wax moth larvae and faeces.
8. Write it down. The findings, the date and that colony's management and treatment records for the year are assessed together.

How do you recognise a colony that starved?

Picture: Many dead bees are head-first in the cells with their abdomens sticking out; the cluster has died on the comb. There is no honey, or very little, around and above the cluster. There is a thick heap of dead bees on the floor.

Meaning: Winter stores were insufficient, or autumn feeding was late and incomplete. Early spring is the most dangerous time for starvation: brood rearing increases, consumption speeds up and there is no forage outside yet.

Isolation starvation

The same head-first picture is seen, but full combs of honey stand two or three frames away. There were stores, but the cluster could not reach them in the cold. In cold periods a winter cluster mostly moves upwards rather than sideways; if the stores are off to the side and a long cold spell prevents the cluster from moving, it starves in a full hive. The risk is much higher in small clusters. The solution is to set up the winter arrangement correctly in autumn and make sure the cluster is in contact with honey.

Varroa collapse: few bees, plenty of honey

Picture: There are very few dead bees in the hive, while honey is often plentiful. Sometimes there is a small cluster consisting of the queen and a handful of workers. The brood is patchy; perforated cappings, dead pupae in the cells and bees that died half-emerged are seen. There are deposits of white, crystalline-looking mite faeces on the upper walls of brood cells and dead mites on the floor. Bees with crumpled wings point to deformed wing virus.

Meaning: The colony did not die of starvation but because it ran out of bees. The winter bees reared in late summer and autumn were born weak because of a high mite load and viruses, and were lost early in midwinter. The cause is usually a mite load left unchecked in August–September.

Signs of queenlessness and laying workers

Picture: Raised (dome-capped) drone brood in worker cells, more than one egg per cell, eggs stuck to the sides of the cells rather than the bottom, an irregular and patchy brood area. The cluster is small and the bees are old.

Meaning: The queen was lost in autumn or failed to mate; the colony could not requeen itself and laying workers took over. A colony that goes into winter queenless or with a poor queen rarely sees the spring. If there is only neatly laid drone brood in worker cells with one egg per cell, the problem is more likely a drone-laying (failing or unmated) queen.

What do damp, mould and faecal staining tell you?

Damp: The inside of the hive is wet, with water droplets on the crown board and outer combs, a puddle on the floor and black stains on the wood. Ventilation is inadequate, the roof leaks, or the hive stands in a hollow in the shade. Condensation dripping onto the cluster wets and chills the bees; in winter damp is at least as dangerous as cold.

Note: mould forms in a hive soon after death. Mould on the combs should not be counted as the cause of death on its own; it must be assessed together with the state of the cluster and the stores.

Faecal staining (dysentery): Brown faecal stains appear on the top bars, on the combs and around the entrance. The bees have been unable to make cleansing flights for a long time and their gut load has built up. Causes include Nosema infection, a long cold spell, honeydew honey in the winter stores or unsuitable syrup. The appearance of dysentery is not proof of nosema; a definite diagnosis requires microscopic examination of dead bees in a laboratory.

Mice, wax moth and robbing: cause or consequence?

Mice: Gnawed combs, heaps of wood shavings and leaves under the frames, nest remains and a sharp smell. No mouse guard was fitted. A mouse can kill a colony by gnawing the combs near the cluster and disturbing the bees; sometimes it moves in after the colony has died of something else.

Wax moth: Combs laced with webbing, cocoons and larvae. A strong colony does not let wax moth in; wax moth is usually not the cause of death but a consequence. The real cause must be looked for underneath the moth damage.

Robbed hive: Chewed cell edges, lots of wax debris on the floor and in front of the entrance, emptied honey combs. A colony that was robbed was already weak or dead; robbing is also a serious risk of spreading infection.

Suspected foulbrood and poisoning

In every autopsy the brood combs should be checked for foulbrood: sunken, darkened and perforated cappings, dry scales stuck to the bottom of the cells, a bad smell. American and European foulbrood are notifiable diseases. If you suspect them, keep the hive closed, do not touch other hives with the combs or tools, and notify the official veterinary service / local agriculture authority; the diagnosis is made in the laboratory.

Poisoning: Sudden, mass death in front of the entrance and inside the hive, bees with their tongues out, trembling or crawling. It is usually an in-season picture coinciding with the spraying period, not a winter one. If you suspect it, take a sample of dead bees and freeze it, record the date and any spraying nearby, and report it to the authorities.

Summary table of autopsy findings

What should you do after the autopsy?

• Set the combs aside: Until the cause is established, no comb or honey is given to another colony. Combs suspected of disease are destroyed as directed by the authorities.
• Protect clean comb: Sound combs showing no sign of disease are protected against wax moth (e.g. by freezing them for a while) and stored in a closed place.
• Clean the hive: The floor is scraped, dead bees are removed, the wooden boxes are scraped and cleaned; the hive is dried before being used again.
• Check the other colonies: See whether the same cause (especially varroa) is still at work in the rest of the apiary.
• Complete the record: Note the cause, the date and the action to be taken. Next year this note will be your most valuable resource.