INSTINCT 151 



remains in the dark of the hive tending the young. Through- 

 out this first period the bee depends on the sense of touch 

 and smell. Gradually during the second period, which ex- 

 tends from about the tenth to the twentieth day, the eyes 

 come into play, and, after having worked on the wax cells, 

 building and cleaning them, the bee becomes a guard at the 

 main gate of the hive. Just as the second period comes to a 

 close short flights are taken into the open. The third period, 

 from about the twenty-first day until death, is spent mainly 

 in collecting honey and pollen. Each worker is equipped 

 not only with the instincts necessary for its work, but also 

 with structural gadgets such as mandibles, antennae cleaners, 

 pollen basket, comb, wax cutter, and so forth, all built into 

 the body and legs. 



Von Frisch and others have been able to follow the whole 

 life cycle of the worker rather intimately. Upon emerging 

 from its pupa, the young adult gnaws open the thin wax lid 

 of its cell, drys itself out, and within an hour is busy clean- 

 ing out cells from which other bees have hatched. The 

 worker cleans the cells with saliva, for it is only after this 

 treatment that the queen will lay an tgg in the cell. In the 

 first three days the bee works and rests, taking life at a lei- 

 surely pace; and, if it is cold outside, it will add to its cell- 

 cleaning duties by hovering over the grubs, giving them the 

 warmth of its body. Soon the nursing instinct takes over; 

 at about the fourth day the bee begins feeding the older 

 grubs with honey and pollen from the hive storehouse. 

 Very young grubs cannot digest raw pollen and so the 

 worker, about six days after having pupated, undergoes a 

 salivary glandular change that makes it possible for it to 

 break up and mix a kind of pollen "milk" w^hich it feeds to 

 the young. This is one of the few cases in nature that paral- 

 lels the maturing milk glands of the human mother. In four 

 more days the swollen salivary glands shrink and the worker 

 begins new activities. She takes nectar from returning for- 

 aging workers and pumps it into honey-storage cells. She 



