182 Fiftieth Report ox the State Museum 



Society, of 1877. I was misled by Mr. Smith, of the British Museum. 

 Dr. August Forel, however, subsequently corrected my error and des- 

 cribed this species as a new one, viz., Formica cxsectoides. We have F. 

 rufa in this country, I have observed and studied it in Colorado, and 

 know that it is found in the Dakotas, but I have no knowledge of its 

 being found in the New England States or in Eastern New York " 



In consideration of Dr. McCook's expressed deference to Mr. Per- 

 gande's views, his letter was submitted to Dr. Howard, chief of the 

 Entomological Bureau at Washington, who returned the following com- 

 ments by Mr. Pergande: 



" Regarding our mound-making ants I will say that the genuine 

 Formica rufa has so far not been found in this country, but that there 

 are numerous forms more or less nearly related to it which occur in dif- 

 ferent sections of the United States. One of these forms, F. exsectoides 

 Forel, appears to be an exclusively eastern species and has so far been 

 found only in Virginia, Pennsylvania, New Jersey and New York, 

 whereas the most common form, occurring in Colorado, Utah, Montana, 

 Wyoming, the Dakotas and Nebraska, is not F. exsectoides, as stated by 

 Dr. McCook, but F. obscuripes Forel, which up to the present time has 

 not been observed east of the Missouri and Mississippi. As to Camr 

 ponottis Pennsylvojiicus, I have never observed it to build extensive nests 

 in the ground, either near dwellings or in the woods, although occasion- 

 ally I have found small nests under stones near the base of large oak 

 trees which were probably connected with breeding chambers m the 

 large and partly decayed roots of the trees. Most commonly I found 

 them in dead trunks or stumps, generally oak, which had been perforated 

 in all directions by wood-boring larvae. Whether the ants which Pro- 

 fessor Riley observed as having built a large nest in the ground of a back- 

 yard in this city really were C. Pennsylvanicus or not, I am unable to say. 

 I incline, however, to the belief that they were Formica snbsericea Say, 

 which has the habit of building large and rather flat nests in the ground." 



In the recent " Comstock's Manual for the Study of Insects," Formica 

 exsectoides is briefly referred to as being the builder of our largest ant- 

 hills; these are often five or six feet across, and sometimes more than 

 twice that in diameter. The head and thorax of this ant are rust-red, 

 while the legs and abdomen are blackish brown. This species has been 

 supposed to be tlie same as the European wood ant, Formica rufa, and 

 is referred to in many books under that name. 



