410 



AMERICAN SPIDERS AND THEIR SPINNINGWORK. 



Mr. George T. Atkinson, who has given some attention to tlie Ameri- 

 can Territelarite, dissents from Mr. Moggridge's supposition that this and 

 other inside doors aifords tlie Trajidoor spider a means of escape when 

 pursued by an enemy, the view whicli I have favored in the foregoing 

 pages. Mr. Atkinson, on the contrary, found indications that the main 

 tube of Myrmeciaphila foliata^ is constructed to serve as a gallery for the 

 passage of ants or otlier insects, and that the branch so constructed is a 

 real trap in whicli the spider awaits the passing of an ant, when it opens 

 the door and catches the insect. In support of this opinion, he states that 

 he found that the trapdoor nests were all made in places where ants had 

 underground })assages ; that the main tube connected directly with some of 

 the ant galleries ; that the trapdoor at the surface of the ground had the 

 appearance of being little used ; and, finally, that one nest had only one 

 door, which led into a short tube that opened into the floor of a broad 

 hall in an ant's nest leading into several galleries. This hall was the 

 gangway to the surface of the ground made by the ants, and through this 

 the siaider probably entered the hall to construct her branch tube into 

 the floor. 



Again, in May, at Chapel Hill, North Carolina, Mr. Atkinson found a 

 nest of the same sjjecies under conditions which seemed to give conclusive 

 evidence that the main tube is intended to entrap un- 

 wary insects as they pass the door of the branch where 

 the spider lurks. Tliis nest was made in a broad foot 

 path where the clay soil was very hard. It was discovered 

 by seeing the open door. The following day Atkinson 

 visited the place with trowel in hand, to take up the spi- 

 der. He found the door still open. The main tube was 

 about nine inches long ; the branch about one inch long, 

 situated six inches from the surface of tlie ground. In 

 this the spider was found. The door to the branch was 

 a "cork" door, that is, a thick beveled one, while that at 

 the surface of the ground was a "wafer" or thin door. 

 It appears in cases where the spider's tube is not made 

 in the ant's nest, that the outer door is .set open, thus 

 offering an attractive place for insects crawling on the sur- 

 face of the ground in search of food. They enter the main tube and, as 

 they pass tlie branch, the door is suddenly thrown open, and to their sur- 

 prise they are taken captive and made a meal of by the cunning spider. '-^ 

 There is no doubt that Mr. Atkinson is correct in so far as the burrow 

 of the Trapdoor spider does serve as a true trap for the capture of ants. 

 Mr. Moggridge shows this in the case of Nemesia ccementaria. (See above, 



Fig. 355. Diagiamatic 

 view of Truncata, clos- 

 ing her burrow with 

 lier abdomen. 



^ Entomologia Americana, October and November, 1S86. 



2 Psyche, Cambridge Entomological Clul), Vol. A'., July-August, 1S8S, page 80. 



