20 COLORATION IN POI.ISTES. 



excepting that the spot of the second segment was half yellow and half 

 ferruginous. Its most striking character, however, was a slightly fer- 

 ruginous prothorax bordered w4th yellow. This nest also shows great 

 range of variability. While some of its members occur in the xanthic 

 series, and that characterized by the small yellow lateral dot, and while 

 it is prominent in the melanic series, still it is best represented in the 

 modal class for the whole group. The light ferruginous appears in 

 the prothorax of 24 members of the colony, though this varies from a 

 slight tinge near the internal border to a blotch covering the dorsal 

 aspect. 



The two nests, a and b, were suspended side by side under the eaves 

 of the same building. It might be expected, then, that any change in 

 external conditions, such as temperature and humidity, would affect 

 the two equally ; but even if further study should incline us to admit 

 the influence of such conditions in bringing about this range of varia- 

 bility, still it remains patent that, instead of haphazard variations, we 

 have here, in the main, a rather close adherence to the characters of 

 the known parents. 



Relation of Color Pattern to the Time of Emergence. 



To determine the relation of color pattern to the time of emerg- 

 ence, the wasps belonging to nests h and m were taken, and those 

 that had emerged before a certain date compared with those that 

 emerged afterward. The time of emergence of all wasps which 

 passed part of their pupal period indoors was also plotted, but in 

 neither case did I obtain evidence that the depth of coloring or kind 

 of pattern was in any wa}- related to the season or time at which the 

 wasp developed. Slight differences were, however, observed between 

 the specimens which had developed in the house and those captured in 

 the open. Thus, in several cases, captures of adults were made from the 

 nest, which was then brought indoors and the pupae allowed to develop 

 there. The imagines which emerged from these nests showed a slight 

 tendency toward duller coloration than that possessed by those captured 

 in the open. There is also a somewhat smaller range of variability 

 observable here. 



These results point to a degree of dependence on environmental in- 

 fluences, an inference which is strongly borne out by further obser- 

 vations on the color differentiation in the group ; but. however the 

 representatives of the genus in a given locality seem to have been 

 played upon by these influences, the ensuing variations for the sepa- 

 rate colonies do, nevertheless, tend to cluster about certain central 

 types, namely, those to which belong the female parent or parents of 

 the colonies. 



