August 8, 1884/ 



SCIENCE. 



115 



every case, the spiders raised a bulwark of 

 earth, one having attached a single sliver of 

 pine shaving, the only thing within her reach. 

 At times the grass is curved around the open- 

 ing, as if a wisp had been, taken, and the tower 

 formed at almost a single stroke, without the 

 labor involved in placing each blade sepa- 

 rately. Near the fa- 

 vorite field, a house- 

 wife, in the annual 

 frenzy of house- 

 cleaning, had thrown 

 out a quantity of 

 coarse straw, which 

 some of the Tarantu- 

 las utilized by erect- 

 ing towers (fig. 2) 

 of comparatively im- 

 mense straw logs. 

 Two miles from the 



latter was found a lofty edifice (fig. 3) built 

 of large pieces of brown, partially decayed 

 wood from an old railroad tie. Mrs. Treat 

 has witnessed their construction by another 

 species. I have not observed the entire pro- 

 cess. 



The spiders' favorite position is a crouching 

 one at the summit, the legs within the tower, 

 and supported by the walls. At the sight of 

 any approaching object, they dart backward 

 into the burrow. They are not disturbed by 

 surface vibrations. Footsteps, even the pas- 

 sage of a heavy wagon within five } T ards of 

 the pit, do not affect them ; but the slightest 

 movement of the observer, two feet distant, 

 or the sudden swajing of a bush, sends them 

 to the burrow immediately. Dr. H. C. McCook, 

 writing in a popular magazine, says of the use 

 of these erections, that "they probably serve 



so far as I am aware, have made no state- 

 ments as to the method of food-capture, when 

 the food fails to voluntarily scale the walls. 



The towers are observatories and transmit- 

 ters of signals to the spider when below. From 

 them she scans the field, as the robber barons 

 of the olden time, from their battlements, 



watched for the com- 

 ing of the caravan. 

 The spider peers 

 through the scanty 

 grass-blades, se- 

 lects her victim, and, 

 as I have witnessed, 

 leaps from the sum- 

 mit to seize the prey. 

 I have seen her 

 spring at a fly on 

 Fig. i. the ground, missing 



it, of course. But 

 she does not always wait for food until the pit 

 and tower are completed. I have seen her 

 dart from the edge of an unfinished burrow, 

 capture an ant three inches distant, and retire 

 to the shallow cave. Ten minutes later she 

 re-appeared empty-handed, and almost imme- 

 diately attempted to seize another near by, but 

 failed to do more by her frantic efforts than 

 scrape up a heap of loose earth. 



The towers are so loosely constructed that 

 an ant can scarcely run over the walls without 

 making enough rattling to admonish the con- 

 cealed spider, which at once hurries to the top, 

 and, if the insect is acceptable, takes it in. 

 A black ant running over the foundations 

 almost invariably brings the spider up ; and the 

 gentle tapping of a straw, or even dragging a 



Fig. 2. 



Fig. 3. 



as watch-towers, from which the keeper may 

 observe the approach of her enemies," as an 

 attraction to roving insects, and perhaps to 

 prevent flooding of the cavern by rain. The 

 towers in this locality are far from being water- 

 proof : they are used exclusively, I think, to 

 facilitate the capture of food. But observers, 



straw across the dead grass in contact with 

 the walls, is quite sure to be followed by the 

 arachnid's appearance. The sense of direc- 

 tion, or the ability to perceive whence the dis- 

 turbance proceeds, is well developed. The 

 spicier always ascends on that side to which 

 the straw is applied, and the same individual 



