Page:Supplement to harvesting ants and trap-door spiders (IA supplementtoharv00mogg).pdf/109

 the struggle for existence; the times and seasons of its activity, and in many cases even the structure and position of its dwelling-place will be governed by this same all-important question of food-supply.

I have now detected the remains of insects, and of ants especially, in the nest of every species of trap-door spider which I have examined in situ; very frequently, however, one may open several nests in succession without finding any of these débris, and at other times they will only be detected beneath the existing bottom of the tube, layers of silk having been spun over successive layers of refuse.

The horny coats of ants form by very far the largest proportion of these remains, and I have lately been much struck by the number of instances in which, while digging out ants' nests at Mentone, I have found trap-door nests (especially those of N. Manderstjernæ and N. Moggridgii) in their midst, the tubes often traversing the very heart of the ants' colony and coming into close contact with the galleries and chambers of the ants. The doors in these instances had almost always escaped my notice, and, indeed, they so closely resembled the surface of the ground that even when I knew, from having accidentally cut across the tube below ground, that one of these doors must lie near a given spot, yet I could only discover it by following the passage from below upwards. This perfect concealment is doubtless of essential importance to the spiders' success in life, for, if they once alarmed the whole colony of ants and let them know the exact whereabouts of their lurking-place, they would soon learn to avoid it.