FORMICA. 3 



armies, and their approach is welcomed by the negroes, who 

 quit their dwellings for a time, the ants entering and destroying 

 every species of vermin with which they may he infested, thus 

 rendering incalculable service to the inhabitants. 



The number of species at present discovered in this country 

 is twenty-five, and as new ones are still being occasionally 

 added, there is no doubt that the number will yet be consider- 

 ably increased. With two exceptions, F. rufa and F. conger ens, 

 all the British species belong to the division of Mining Ants — one, 

 F. fuliginosa, usually selecting decaying trunks of trees, posts, 

 &c. : but this insect will in rare instances be found mining in 

 banks or mud-walls; such occurrences are, however, seldom ob- 

 served. The F.flava appears to differ in one point of its eco- 

 nomy from all our native species — the last brood of workers are 

 carried down iuto the deepest recesses of their subterranean 

 dwelling, and there pass the winter months in a state of tor- 

 pidity. I have found numbers in this situation in the depth of 

 winter; and such larvae are much more pubescent than we find 

 them during the summer months. We have frequently inspected 

 the dwellings of other species, F. nigra, fusca, and cunicularia, 

 in winter, but never found either eggs or larvae. The males and 

 females of F. fiuva in a winged state are also found in the nest 

 much later than any other species ; we have found males as late 

 as the 5th of November. 



The Formicidce may be divided into two great sections — those 

 possessing a single scale or node at the base of the abdomen, and 

 those in which the petiole is divided into two nodes. Of the 

 former group only a single species, Ponera contractu, is fur- 

 nished with a sting ; whilst in the latter division the females and 

 workers all possess that organ. This mode of subdivision, it 

 must be remembered, is only applicable to the British species. 

 As regards the species armed with stings, amongst the exotic 

 group, several other genera having a single node in the petiole, 

 are aculeate ; and amongst the division possessing two nodes, 

 the exotic genera (Ecodoma, Cryptocerus, and some others, are 

 stingless. 



Genus 1. FOEMICA. 



Formica, pt., Linn. Faun. Suec. p. 426 (1761). 

 Lasius, pt., Fabr. Syst. Piez. p. 415 (1S04). 



The maxillary palpi 6-jointed ; the labial palpi 4-jointed. An- 

 tennae geniculated, 12-jointed in the females and workers, 

 13-jointed in the males. Ocelli three, placed in a triangle on 

 the vertex ; the eyes lateral and ovate. The superior wings 



b 2 



