192 BRITISH ANTS. 



and Farren- White 33 describes it as a fragrant scent like that of 

 the musk beetle, but it does not remind me of the odour of that 

 insect. 



Forel gives reasons to show that the seat of this odour lies in the 

 head more than in any other part of the body 22 , as the heads, when 

 crushed, give off a very violent odour, though the thorax and gaster 

 do not seem to be entirely inodorous. 



Landois described a structure in these ants by means of which 

 they can probably stridulate, though Sharp 31 does not consider it 

 to be a true stridulating organ. It consists of delicate transverse 

 lines sculptured on the dorsal surface in the middle at the base of 

 the third gastric segment, the line of demarcation between the 

 general sculpture and that of the basal portion not being very 

 abrupt. There is however no special contrivance on the over- 

 lapping segment to scrape against it, but the friction of the segments 

 together probably produces some sound. 



The colonies of D. fuliginosa are often very populous, and 

 a number of subsidiary nests may occur in neighbouring trees. 

 Rothney found the nests of this ant were extremely abundant in 

 old oak trees at Barham, and two such trees were situated on the 

 opposite sides of a gravel pathway, beneath which the ants had 

 excavated a tunnel of communication 17 . Consequently they are 

 able to overpower any other ants in the neighbourhood, as they 

 can concentrate in vast numbers very quickly at any desired spot. 

 Forel 22 placed the contents of ten nests of Formica pratensis near 

 a tree occupied by D. fuliginosa, and the latter when besieged, 

 obtained assistance from the inhabitants of other trees near, over- 

 whelmed the pratensis with their numbers and captured all their 

 cocoons. Wasmann 40 , in 1884, emptied a sack full of F. rufa at 

 the entrance to the nest of a strong colony of D. fuliginosa in a 

 garden at Exaeten, when the latter swarmed out and drove off the 

 former. 



In September, 1913, 1 placed the large nest I obtained at Oxshott 

 (mentioned presently) in a box on a case with glass sides, open at 

 the top and surrounded by water, which contained a colony of 

 F. rufa under observation. In the night a large number of the 

 fuliginosa workers escaped, and, entering the rufa nest, completely 

 routed the inhabitants some fifty deflated rufa females and all 

 the workers fleeing from the nest. 



Huber 5 and other old writers thought the nests of this species 

 were excavated in wood which was stained black by the ants' acid, 

 but Meinert 14 and then Forel 20 proved this not to be the case. 



They are really made of carton, consisting of chewed fragments 

 of wood and bark, mixed with earth and cemented together with 

 the secretion from the mandibulary glands, which are greatly 

 developed in this ant (see Fig. 42). Forel 20 suggests that the 

 liquid from the metathoracic glands helps to soften the wood 



