Cleaning instinct and hygienic behaviour
Verhalten der Bienen
Two things are often lumped together here.
Two things are often lumped together here. One is cleaning the nest: in the first days after emerging, young workers show pronounced cleaning behaviour. They clean the brood cells, remove cocoon remnants and larval faeces from cell walls and cell bases, and treat the cell with the secretion of their mandibular glands before the queen lays in it again.
The other is the removal of diseased or dead brood. Bee larvae and pupae on the landing board are the visible sign. Possible causes are disease, a cold snap with too few nurse bees, lack of food and also too high a dose of formic acid. With chalkbrood the white-grey mummies lie in front of the hive in the morning, and one approach to treatment explicitly consists of stimulating the cleaning instinct.
In practice this means: what lies in front of the entrance is not a failure of the colony but its defence. The question is what lies behind it. So look at the landing board regularly and, if the amounts are conspicuous, look inside instead of just sweeping it away.