Chronic bee paralysis is treated separately from the other bee viruses because it produces a distinct and recognisable picture. It is one of the few viral diseases that can be identified in the field.

Two forms

The disease appears in two forms; both may occur in the same colony.

The trembling form

• Bees with trembling wings and bodies
• Inability to fly; crawling in front of the hive and on the grass
• Distended abdomen
• Wings held irregularly and apart
• Sick bees gathering in clusters

The shiny form

• Black bees that have lost their hair and look greasy and shiny
• Being attacked by guard bees at the entrance and refused admission
• Death within a short time

Shiny, hairless bees being driven away at the entrance is the most recognisable image of this disease.

How it spreads

It is transmitted by close contact and by food exchange between bees. Crowded and confined conditions accelerate its spread.

The disease is therefore seen more often:

• When bees are confined by long spells of bad weather
• In excessively crowded colonies
• After an intense flow
• After transport

Varroa is thought not to play the determining role it does with other viruses; this is another feature that sets chronic bee paralysis apart.

Impact

The picture usually regresses within a few weeks. In severely affected colonies, however, adult bee loss can be rapid and the colony may reach the point of dwindling away.

Large numbers of dead bees accumulating in front of the hive and on the floor is the typical finding.

What to do

There is no direct treatment. The approach is to correct the conditions:

• Increase the space. Reducing congestion is the most effective intervention
• Improve ventilation
• Clear away dead bees. Prevent accumulation at the entrance and on the floor
• Do not disturb the colony. Unnecessary intervention worsens the picture
• Requeen. This can be effective where it recurs persistently; differences in susceptibility between lines are reported
• Do not unite a weak colony. Uniting a sick colony with a healthy one carries the disease across

Not to be confused with

• Poisoning: Mass mortality in front of the hive is common to both, but poisoning does not produce hair loss and shininess
• Tracheal mite: Bees unable to fly are similar; the distinction is made by microscopy
• Nosema: Faecal marking is the prominent feature