i8z AMERICAN SPIDERS 



Mention of web repair always brings to mind the views of Fabre 

 and others who regard spiders as creatures that, while spinning 

 their webs, must run through the same series of inflexible and in- 

 stinctive actions from start to finish. The spider can build another 

 orb with the pattern and peculiarities of its clan, but cannot repeat 

 an earlier step out of its turn, cannot repair a rent in the lines. By 

 cutting some of the lines it can be shown that the mechanical spider 

 often spins blindly to produce an imperfect caricature of a snare. 

 However, spiders seem not to be quite the automatons that this 

 view demands. 



Many higher orb weavers spin a new web almost every night. 

 Retaining the foundation lines intact, they remove the ragged 

 threads and law down fresh radii and capturing spirals. (It is at 

 this time that they frequently eat the rolled up balls of silk.) Their 

 webs are prepared for a single or for only a few captures; conse- 

 quently there is little incentive to repair a web that will not be 

 used again. Even so, much informal repair, by overspinning broken 

 areas, does go on. 



Some of the orb weavers use the snare for a longer period, and 

 probably do far more informal repair of the rents. It is well known 

 that the silk spiders replace only a part, usually one half, of their 

 large web at one time. In other instances, there may be quite formal 

 repair by replacement of a series of loops, or by keeping intact areas 

 of loops and adding only the spiral or complete turns. The seem- 

 ingly tremendous task of completely replacing an orb web ordi- 

 narily requires less than an hour. The spinning is often done during 

 twilight, when it is easy for an observer to watch the whole process, 

 but others spin during the early morning. 



The principal groups of orb weavers are well represented in the 

 temperate region of North America. Much of what we know about 

 their natural history must be credited to the energy of the Reverend 

 Henry C. McCook, whose fascinating and comprehensive three- 

 volume work, American Spiders and Their Spinnings or k, is one of 

 the classics in arachnology. Superbly illustrated and still authori- 

 tative, this is a primer to which layman and spider specialist alike 

 can refer for dramatic essays on our orb-weaving spiders. 



That all orb weavers represent a single series is undoubted, but 

 that they should all be placed within the single family Argiopidae, 

 the most common practice, is debatable. Some modern types repre- 

 sent lines early detached from the main stream, and now forming 



