2.9. May disease

As its name suggests, May disease generally occurs in May, but it may also appear as early as April or somewhat later, in June. It mainly affects nurse bees when they do not have sufficient water to digest pollen. Cold weather accompanied by dry northeasterly winds favours the onset of the disease. In addition to water shortage, the bacterium Spiroplasma apis or certain types of pollen may also trigger May disease. Scientists assume that the disease is caused by a combination of different factors.