Re: VRD: daddylonglegs vs blackwidow

I have been unable to find exact references on this (although there may be 
some), but I can offer the following observations.   Certainly not all 
pholcids (daddy-long-legs spiders- which are not true daddy-long-legs) 
attack other spiders.   Those in the common genus Psilochorus appear to 
often be peaceful inhabitants of other spider's webs, including black 
widows.   Dan Jennings, a retired arachnologist who still works on 
pholcids, tells me that this live and let live attitude of Psilochorus is 
not found in its larger cousins in the genus Physocyclus. These spiders 
actively seek out black widows and other web-building spiders, attack and 
kill them.  From my own experience I can say that I have a shed full of 
Physocyclus and no black widows, although the latter can commonly be found 
around the yard.

References: (Only for association of Psilochorus and other spiders)

Gertsch, W. J. 1979.  American Spiders.   2nd ed. Van Nostrand Reinhold, 
New York.