I've heard of tests done with various drugs on spiders and the effects on the web. Caffeine caused an erratic web and THC caused the spider to work normally but give up partway through... I forget the rest. Lemme see if I can relocate the link.

EDIT: Here are some links:

http://en.wikipedia.org/wiki/Spider_...webs_and_drugs

http://www.trinity.edu/jdunn/spiderdrugs.htm