WHEELER— ANT LARV^. 321 



males as well as females, are extremely eager for this salivary secretion, the 

 taste of which is slightly sugary. It is easy to observe, especially in 

 Belonogastcr, the insistent demand for this larval product and the tactics 

 employed to provoke its secretion. 



As soon as a nurse wasp has distributed her food pellet among the va- 

 rious larvae, she advances with rapidly vibrating wings to the opening of each 

 cell containing a larva in order to imbibe the salivary drop that flows abun- 

 dantly from its mouth. The method employed to elicit the secretion is very 

 easily observed. The wing vibrations of the nurse serve as a signal to the 

 larva, which, in order to receive the food, protrudes its head from the orifice 

 of the cell. This simple movement is often accompanied by an immediate 

 flow of saliva. But if the secretion does not appear the wasp seizes the 

 larva's head in her mandibles, draws it towards her and then suddenly jams 

 it back into the cell, into which she then thrusts her head. These movements, 

 involving as they do a stimulation of the borders of the mouth of the larva, 

 compel it to secrete its salivary liquid. 



One may see the females pass back and forth three or four times in front 

 of a lot of larvae to which they have given nutriment, in order to imbibe the 

 secretion. The insistence with which they perform this operation is such that 

 there is a flagrant disproportion between the quantity of nourishment dis- 

 tributed among the larvae by the females and that of the salivary liquid 

 which they receive in return. There is therefore a real exploitation of the 

 larvas by the nurses. 



The salivary secretion may even be demanded from the larva wfthout a 

 compensatory gift of nourishment, both by the females that have just hatched 

 and by the males during their sojourn in the nest. The latter employ the 

 same tactics as the females in compelling the larvae to yield their secretion. 

 They demand it especially after they have malaxated an alimentary pellet 

 for themselves, so that there is then no reciprocal exchange of nutritive 

 material. 



It is easy to provoke the buccal secretion of the larvae artificially. Merely 

 touching the borders of the mouth will bring it about. The forward move- 

 ment of the larvae at the cell entrance, causing them to protrude their mouths 

 to receive the food pellet, is also easily induced by vibrations of the air in 

 the neighborhood of the nest. It is only necessary to whistle loudly or emit 

 shrill sounds near a nest of Belonogastcr to see all the larvae protrude their 

 heads to the orifice of the cells. Now it is precisely the vibrations of the air 

 created by the rapid agitation of the bodies of the wasps and repeated beating 

 of their wings that call forth these movements, either at the moment when 

 food is brought or for the purpose of obtaining the buccal secretion which is 

 so eagerly solicited. 



Roubaud summarizes the general bearing of his observations in 

 the following paragraph : 



The reciprocal exchange of nutriment between the adult females and the 

 larvae, the direct exploitation of the larval secretion without alimentary com- 

 pensation by the males and just emerged females are trophobiotic phenomena 

 the elucidation of which is of great importance to an understanding of the 



