278 BRITISH ANTS. 



placed them on the border of a small wood. The ants at once 

 commenced to build a nest, and to attack two colonies of Donis- 

 thorpea nigra and one of D. flava which were situated in the neigh- 

 bourhood, the siege lasting for two or three days, and numbers of 

 the nigra and flava were killed and chased away. The exsecta 

 workers in troops invaded the shrubs in the neighbourhood, and 

 drove away workers of D. nigra and F.fusca, taking possession of the 

 plant-lice belonging to these ants. They also attacked some Cam- 

 ponotus ligniperdus workers on a tree at some distance from the 

 nest, but were eventually repulsed with heavy loss. After some 

 days two nests were established on the borders of the wood, one 

 being built over the nest of one of the vanquished nigra colonies. 

 The exsecta workers never went out alone, at least for the first eight 

 days, but always in bands, so that when one of their number was 

 attacked, twenty other workers would come to the rescue, but they 

 never went near the Camponotus nest again. This exsecta colony 

 flourished and was still under observation in 1874 12 . 



Holmgren has observed that the nests of F. exsecta in the bogs 

 of Lapland are destroyed by the growth of a moss (Polytrichum 

 strictum) which gradually invades the mounds of these ants, and 

 covers them with a dense carpet. The moss is then replaced by a 

 growth of sphagnum, and many other plants eventually take root 

 in it, so that the ants are instrumental in the forming of these 

 hillocks of moss, and hence helping the growth of peat-forming 

 vegetation 26 . 



F. exsecta is a very active and fierce ant, and when its nests are 

 disturbed the workers rush out, swarm all over the invader, and 

 bite most viciously. 



They are somewhat abrupt in their movements ; they possess 

 good sight, but very little individual initiative. When the workers 

 attack other species, they advance together in troops in fairly 

 close formation and always try to avoid the grasp of an enemy 

 a number seizing the latter by its legs and antennae and pulling 

 in different directions as hard as they can, whilst one of their 

 number springs on to the back of the captive and endeavours to 

 cut off its head. 



Large nests are very populous, and a colony may consist of over 

 one thousand, or, as Wasmann suggests, perhaps ten thousand, 

 individuals. 32 



According to Escherich the marriage flight takes place in June 

 and July without swarming 28 ; Andre says the winged sexes 

 appear in June and July 16 , Rothney found males and winged 

 females at Bournemouth on July 14th, 1868 8 , and I have taken 

 them in abundance in nests in the same locality at the end of 

 August and the beginning of September, 1905 ; sex pupae taken 

 in June in Parkhurst Forest and in'July at Rannoch, 1913, hatched 

 in the latter month. 



