Today I killed a cockroach by shining a light on it. I caught the cockroach, put it in a glass cup, and shone a light down on it. After about 30 seconds the cockroach stopped behaving 'normally'; it started twitching and jerking uncontrollably and stopped trying to escape from the glass cup. After about 1 minute the cockroach stopped moving completely. Now, I can think of two very general explanations: 1) The heat from the light killed the cockroach by some mechanism (the cockroach's body was rather hot to the touch after its death) 2) The light, being an electromagnetic wave, interferes with the cockroach's nervous system in such a way that its vital processes are disrupted Can anyone help me to understand what happened? I suspect the first explanation is the most likely. If it is the heat which killed the cockroach, could someone please explain why heat kills things?