Demise of a Butterfly!

I know the topic of this post sounds really macabre...actually it really grossed me out writing it....but today a strange...strange thing happened!...i saw a dead ...lifeless butterfly lying on the sidewalk!....can u imagine my shock and horror...i mean...there it was...this beautiful orange and black hued-winged butterfly...lying there...stone -dead....it was such a strange sight...it got me thinking...do butterflies and insects just drop dead like this...what could have caused it to collapse like this...a flash streak of lightning (it had been raining earlier today..so ...im not completely off my rockers and this doesnt sound THAT..improbable...ok..maybe it was sitting on something that was struck by lightning!)...but i digress....my question and wonderment was about how insects pass away (attempt at making this post less insane)...do they just wither away...highly unlikely...or do they have strokes (my really really miniscule knowldge of zoology limits me...yes that much i know...its not botany!)...anybody out there...knows?