 The English mycologist John Ramsbottom reported that Amanita muscaria was used for getting rid of bugs in England and Sweden , and bug agaric was an old alternate name for the species . French mycologist Pierre Bulliard reported having tried without success to replicate its fly @-@ killing properties in his work Histoire des plantes vénéneuses et suspectes de la France ( 1784 ) , and proposed a new binomial name Agaricus pseudo @-@ aurantiacus because of this . One compound isolated from the fungus is 1 @,@ 3 @-@ diolein ( 1 @,@ 3 @-@ Di ( cis @-@ 9 @-@ octadecenoyl ) glycerol ) , which attracts insects . It has been hypothesised that the flies intentionally seek out the fly agaric for its intoxicating properties . An alternative derivation proposes that the term fly- refers not to insects as such but rather the delirium resulting from consumption of the fungus . This is based on the medieval belief that flies could enter a person 's head and cause mental illness . Several regional names appear to be linked with this connotation , meaning the " mad " or " fool 's " version of the highly regarded edible mushroom Amanita caesarea . Hence there is oriol foll " mad oriol " in Catalan , mujolo folo from Toulouse , concourlo fouolo from the Aveyron department in Southern France , ovolo matto from Trentino in Italy . A local dialect name in Fribourg in Switzerland is tsapi de diablhou , which translates as " Devil 's hat " . 
