32 BULLETIN 1222, U. S. DEPARTMENT OF AGRICULTURE. 



ing is being resumed. Further evidence to substantiate this conclu- 

 sion is found both by weighings of the food present and by a com- 

 parison of the composition of food found in cells containing 2-day 

 and 3-day larvae. Sturtevant shows that there is a considerable 

 increase in the amount of food found in cells containing 3-day larvae 

 over the amount found with 2-day larvae. The composition of the 

 food is changed also by the third day. This is most conspicuous 

 through the fact that the color of the food found within the cells 

 containing larvae of 3 days or more varies with the color of the 

 pollen being brought in from the field, no stores of old pollen being 

 present in the hive used in this experiment. The larval food found 

 in cells containing 1-day and 2-day larvae is of a uniformly grayish- 

 white color. 



With the change of food it appears that a different method of 

 feeding, is gradually adopted, mass feeding giving place to pro- 

 gressive feeding; that is, the food is no longer given in quantity 

 and in excess of immediate needs, but is supplied at about the same 

 rate at which it is ingested. The bee larva is a rapidly growing 

 organism, hence it follows that if the food is supplied from time to 

 time, it must be introduced in rapidly increasing amounts. This 

 necessitates either more visits or longer feeding periods, or both of 

 these factors may be increased. The last is actually the case. The 

 number of visits is increased, particularly on the fourth and fifth 

 days, and the time of the visits is notably lengthened. 



Mass feeding, if this is strictly what happens in the case of the 

 food first supplied, taken together with the later progressive feed- 

 ing, shows an interesting similarity to the behavior of certain soli- 

 tary bees y some of which practice mass feeding exclusively, while 

 others, recently investigated, practice progressive feeding. It also 

 has a resemblance to the feeding behavior of the bumblebee, which 

 lays the eggs on a lump of " pollen-paste " to furnish the first food 

 after hatching, and then some time after the larva is hatched a 

 type of progressive feeding is begun. A. similarly modified type of 

 mass feeding is shown in the case of the queen larvae of the honeybee. 

 The large queencell is rapidly crowded with food before it is 

 sealed, and the larva completes its development while eating more 

 food which is inclosed with it. Frequently a mass of dried food 

 remains even after the emergence of the queen, which confirms the 

 supposition of mass feeding in this instance. 



The fact that the food of the larva up to 2 days is placed in the 

 cell beside the larva and is apparently not fed into the mouth seems 

 to preclude the possibility of mutual feeding of the nurse bee and 

 larva during this period. Such reciprocal feeding has been de- 

 scribed for certain social wasps and ants, and to this phenomenon 

 Wheeler has given the name trophallaxis. Since the queen larva is 

 also fed by mass feeding, perhaps exclusively by that method, there 

 is little or no indication of trophallaxis in this instance. Koubaud 

 has shown that in certain wasps in which trophallaxis is observed 

 there is a decided disproportion between the amount of material 

 given by the nurse wasp and that received by it from the larva being 

 fed, the secretion received being sometimes greater than the food 

 given by the nurse. Reciprocal feeding has never been observed in 

 the honeybee, but since the food given to the older larvae is not com- 

 plex in character and probably requires no great amount of work on 



