No. 10. — A Revision of the Ants of the Genus Formica {Linne) Mayr} 

 By William Morton Wheeler. 



No revision of the American ants of the circumpolar genus Formica 

 has been published for many years, notwithstanding the fact that it 

 comprises some of the most important members of our insect fauna. 

 Mayr,^ who in 1886 first attempted a revision of this genus, cited only 

 seven species and seven varieties from North America. We are in- 

 debted to Emery, however, for the first really serious account of these 

 ants. In 1893 this investigator gave us, in a very succinct and admir- 

 able paper,^ a critical account of all the known American forms, on 

 the basis of collections made by Mr. Theodore Pergande and Rev. 

 P. J. Schmitt. In this paper eight species, twelve subspecies, and 

 fifteen varieties are recognized as being peculiar to our fauna. During 

 the twenty years that have since elapsed a much greater amount of 

 material has found its way into public and private collections, and 

 during the past thirteen years I have described several species and 

 have accumulated both tlirough my own efforts and through the very 

 generous aid of many correspondents so large a collection of Formicae, 

 that it seems advisable again to " take account of stock" of the North 

 American forms. A study of all this material enables me to recognize 

 thirty-one species, nineteen subspecies, and forty-three varieties as 

 belonging to our fauna. Since many of these are very closely 

 related to the Palaearctic or Eurasian forms I have included a brief 

 account of the latter in the present paper. In this part of my work 

 I have made extensive use of Emery's recent revision of the Palae- 

 arctic ants.^ 



The species of Formica can be readily distinguished from the species 

 of the other genera of the subfamily Camponotinae by the following 

 characters : — 



The workers are small or medium-sized ants, often varying consid- 



1 Contributions from the Entomological Laboratory of the Bussey Institution. 

 Harvard University. No. 59. 



2 Die formieiden der Vereinigten Staaten von Nordamerika. Verh. Zool. hot. ver. 

 Wien, 1886, 36, p. 419-464. 



3 Beitrage zur kenntniss der nordamerikanischen ameisenfaima. Zool. jahrb. Syst., 

 1893, 7, p. 633-682, 1 pi.; 1895, 8, p. 257-360, pi. 8. 



* Beitrage zur monograpbie der formieiden des palaarktischen faimengebietes . 

 (Hym.) Teil. 7. Deutsch. ent. zeitschr., 1909, p. 179-204, 16 figs. 



