Half-moon syndrome

What is half-moon syndrome?

Half-moon syndrome does not appear to be a disease of honey bees, since no organism has ever been found that produces the syndrome’s effects. The cause of half-moon syndrome is unknown, but research indicates that it is probably nutritional and/or genetic in origin.

The features of half-moon syndrome closely resemble those of European foulbrood and parasitic mite syndrome. These include patchy brood patterns, perforated cappings (in advanced stages), curled larvae (either c-shaped in the bottom of the cell, or twisted in a “half-moon” shape from the bottom to the top of the cell), yellowish colouration and tracheal outline, and a sour, urine-like smell.

Differences to AFB

51_Fig_Multiple_eggs_in_a_cell_of_a_bee_colony — Figure 51: Multiple eggs in a cell of a colony with half-moon syndrome

The only major difference in appearance between half-moon syndrome and EFB or PMS is the presence of multiple eggs in cells. In half-moon syndrome, this multiple egg laying can be found in many worker cells (Fig. 51), with the eggs attached in chains, rather than all fastened to the bottom of the cell (as is the case when the colony has laying workers). Multiple egg laying is not associated with AFB.

In hives with advanced cases of half-moon syndrome, a high percentage of drone brood (including capped brood) can be found in worker cells, with very little worker brood present. Beekeepers generally believe that such a symptom is the result of a poorly mated or old queen, and simply re-queen the hive. Re-queening usually alleviates half-moon syndrome.

Because the distinguishing features of half-moon syndrome so closely resemble the symptoms of EFB and parasitic mite syndrome, beekeepers should always contact MPI, free phone 0800 809 966.