Experiment showing the effect of psilocybin on a garden spider. A young female Garden Spider (Araneus diadematus) built a "control web" (A) on one day in the laboratory frame, with the "drug web" (B) on the following day. After the control web had been destroyed, the spider had ingested 150 mg/kg of a psilocybin solution, a drug which causes hallucinations and illusions in humans. Note the characteristic effect of this drug on spider web-building, namely a smaller but regular orb. Disturbances of spirals at the upper end of both webs were caused by the spider after completion of web construction when it ran upward out of the web.