1906.] Wheeler, Habits of the Tent-building Ant. 1 5 



rado at an altitude of 6000 to 7000 feet, where the scrub oaks grow 

 among the red volcanic rocks, I have found a much greater tendency 

 to construct masses of carton in the nests under stone. One of these 

 masses of about f the natural size is shown in PI. V. A stone had 

 rolled down on to a lot of dead oak leaves and the spaces between these 

 had been built into a series of inosculating and slightly concentric 

 chambers by means of black carton partitions carried up to the lower 

 surface of the stone. In other nests the pebbles or twigs on which 

 the stone happened to lie were similarly covered with irregular masses 

 of carton. A fragment of this material from such a nest is shown in 

 Fig. 3, PI. IV. In all these cases the surface of the carton was covered 

 with a delicate blue mould which probably derived its nutriment 

 from the glandular secretion used by the ants as a mortar in agglutin- 

 ating the- fine particles. A similar mould has been observed by 

 Lagerheim ^ covering the carton plates in the nests .of the European 

 Lasius fuliginosus, and is said to be eaten by the ant-larvse. In the 

 case of the Colorado lineolata, the layer of mould would be an entirely 

 inadequate food supply for the thousands of larvae found in one of 

 these nests, and there is nothing to indicate that it is of the slightest 

 use to the ants. The blackness of the carton in these nests is due to 

 the large amount of soil used in its construction. 



It is difficult to understand wh}^ the ants build masses of carton 

 in these nests under stones unless they are exhibiting a merely ves- 

 tigial instinct which may be called into activity whenever they find 

 leaves or twigs — the very objects about which their arboreal an- 

 cestors built carton nests — in the way while they are excavating. 

 The covering of the rootlets with carton in the Colebrook nest above 

 described may also be taken to indicate that contact with vegetable 

 surfaces acts as a stimulus to which the ants respond with an ancient 

 and abortive instinct. This response may, however, assume extra- 

 ordinary proportions in lineolata colonies that are compelled to return 

 to a strictly arboreal life like their tropical ancestors, as shown in the 

 following observation published several years ago by Atkinson 2 : 



"The nest was built several feet from the ground on a bush, in the 

 marshes bordering Broad Creek, Hyde County, N. C. . . 



"This nest is about eighteen inches long by twelve inches in cir- 

 cumference at its greatest diameter. I made a longitudinal section 



of it, and had a photograph taken, so as to represent both the 

 1 



' Ueber Lasius fuliginosus (Latr.) und .seine',Pilzzucht. Entomol. Tidskr., Arg. 21, pp. 17-29, 

 4 figs. ... 



- Singular Adaptation in Nest-Making by an Ant, Creitiaslopaster lineolata Say. Am. Natural- 

 ist, Vol. XXI, 1887, pp. 770, 771, pi. xxvi. 



