206 JOHN L. PRICER. 



the voided wood that the larvae had left in the burrows. As the 

 wood gradually decays and in cases where the ants follow larvae 

 that bore in decayed wood they do enlarge the galleries and 

 shape them into chambers which are more or less characteristic, 

 but even here the style of the architecture is determined largely 

 by structure of the wood and the instinct of the particular larva 

 followed. The influence of the structure of the wood is shown 

 in Figs. 5 and 6. Fig. 5 shows a radial section of decayed 

 oak in which the more durable medulary rays formed a limit to 

 the gallery in one direction and in Fig. 6 is shown a tangential 

 section of the same wood in which the dense summer wood of 

 an annual ring forms the limit in the other direction. Many 

 observations similar to these have convinced me that these ants 

 do not build their own galleries in solid woo.d. They either 

 follow the wood-bores or work in badly decayed wood and if 

 this conclusion is true their economic importance must be ex- 

 tremely slight. 



Guests and Parasites. 



Probably the most distinguished and interesting guests which 

 have been found with ant colonies are certain Lomechusini, 

 several species of which are very common guests with the ants 

 of continental Europe. This family is represented in North 

 America by the single genus Xenodusa, and the best known 

 representative of the genus is X. cava, Fig. 7. Wheeler, in a 

 review of the observations made on this beetle (" Polymorphism 

 of Ants," Bulletin American Museum of Natural History, Vol. 

 XXIII., pp. 35-40), shows that, so far as reported, only five 

 persons, viz. : Leconte, Blanchard, Muckermann, Schwarz and 

 himself, have ever seen it and each of these only rarely. Schwarz 

 found it with C. pennsylvanicus, and Blanchard with a colony of 

 large black ants which were probably of the same species. No 

 one has before seen it with C. ferrugineus. By referring to Tables 

 III. and IV. of this paper, it will be seen that I have found it to 

 be quite abundant in this region, and by a comparison of these 

 two tables, it will be seen that the beetle seems to prefer C. ferru- 

 gineus as a winter host. Wassmann and Wheeler are of the 

 opinion that the beetle simply hibernates with these larger ants 

 and then in the spring migrates to the nests of some smaller ants 



