THE WOOD-BOREBS. 



83 



days, while still others survived for two weeks. Compared with, 

 the work of the Pelopaei it would seem that a smaller number 

 of the spiders are killed at once, while a larger number die after 

 the lapse of a few days. jSTone of the victims of Trypoxylon 

 live so long as the most perfectly paralyzed spiders of the mud- 

 daubers. The two longest lived spiders of Trypoxylon lived 

 ten and fifteen days respectively, while with Pelopaeus one sur- 

 vived until the thirty-eighth and one until the fortieth day. 



The accompanying table shows the number of days that the 

 Trypoxyloii spiders lived after having been captured and oper- 

 ated upon. "We wish to avoid any suggestion that would imply 

 a lack of skill on the part of the wasps, from the fact that they 

 killed rather than paralyzed their victims. Possibly the best 

 criterion of their success is the rapidity with which the spiders 

 are captured and stored, irrespective of their condition. Dead 

 spiders seem to be quite as wholesome for their nurslings as 

 living ones. 



Table No, I. — Shoiving length of life of spiders found in nests of 



T. ruhrocinctum. 



The egg requires from forty to sixty hours for its develop- 

 ment and the larva feeds for seven or eight days before spinning 

 its cocoon. Those that we watched, usually first disposed of the 

 abdomen and then of the cephalothorax; sometimes they would 



