MODES OF FIGHTING. 17 
vent which they make the entrances small, and often 
station at each a worker, who uses her head to stop 
the way. The smell of this species is also, perhaps, a 
protection. Tetramoriwm cespitum has the habit of 
feigning death. This species, however, does not roll 
itself up, but merely applies its legs and antenne 
closely to the body. 
Formica rufa, the common Horse ant, attacks in 
serried masses, seldom sending out detachments, while 
single ants scarcely ever make individual attacks. 
They rarely pursue a flying foe, but give no quarter, 
killing as many enemies as possible, and never hesi- 
tating, with this object, to sacrifice themselves for the 
common good. 
Formica sanguinea, on the contrary, at least in 
their slave-making expeditions, attempt rather to 
terrify than to kill. Indeed, when invading a nest, 
they do not attack the flying inhabitants unless these 
are attempting to carry off pupx, in which case the 
F. sanguineas force them to abandon the pupe. 
When fighting, they attempt to crush their enemies 
with their mandibles. 
Formica exsecta is a delicate, but very active 
species. They also advance in serried masses, but in 
close quarters they bite right and left, dancing about 
to avoid being bitten themselves. When fighting 
with larger species they spring on to their backs, 
and then seize them by the neck or by an antenna 
They also have the instinct of acting together, three 
