1928] 
Trophallaxis in Polistes pallipes 
155 
but has been recorded for other species of Polistes and other 
insects. Janet was able to prove in 1903 that the secretion is a 
product of the salivary or the spinning glands, and that it flows 
from an opening at the base of the labium. This act as I have 
observed it in orphan colonies must have been purely instinctive, 
since the individuals certainly had never been taught this trick, 
and the larvae responded readily to the noisy tapping. They 
freely gave up this honey-dew also without associating this 
action with the noisy vibrations, for teasing the mouth-parts 
with a pin-head caused the same response. It is quite likely 
that, as Wheeler has so ably shown, this behavior is the cause of 
the beginning of the social habit. There is, however, another 
phase to the condition of trophallaxis, in the hypothesis that it 
might be absolutely necessary for the larva to rid itself of the 
substance that the workers so willingly take. In larvae of this 
and various other species, there is no provision made for ridding 
the body of excretory products. During the period of feeding, 
the larvae, being confined in close quarters, have no place for 
refuse. In most of the Trypoxylon wasps and in mud-daubing 
wasps, Sceliphron ccementarium , this excretory material is passed 
from the body in one mass, just before pupation; it is spread 
and moulded to form a shell or cocoon covering the body. In 
Polistes cells, after the adults have emerged, there always remains 
up against the roof of the cell, a hard reddish mass of chalky 
material which is the sum total of the excretory products ac- 
cumulated during the life of the larva. The thought comes to 
me, if the solid excretory matter leaves the body in that form 
what becomes of the liquid excreta? In the plant-lice, we know 
that the honey-dew, so much relished by the ants, is waste 
matter; why should that emitted by P. pallipes larvae not like- 
wise be excretory material? The only difference at once ap- 
parent is that one insect is relieved by delivery of this liquid 
from the posterior end, and the other by way of the anterior 
aperture of the body — a small digression when one considers how 
Nature disregards the method to gain her ends economically. 
The question still remains, probably never to be solved, 
whether the Polistes nurse feeds the larvae in order to get the 
honey-dew, or whether she relieves the larvae of their moisture 
