ELI5: Why and how do insects stay still for hours?

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It’s already been said, but to really ELI5: I dunno how much you know about computer software, but all computer programs are just a giant pile of “IF;THEN” instructions, for example, “IF: chrome icon is double clicked; THEN: open chrome browser”. Bugs are so incredibly simple that their nervous system/conciousness is barely more complex than modern computer software(and may actually be less complex than modern highly advanced software), so a bug is literally driven by the biological equivalent of “IF;THEN”, as in, “IF: bug lands in web; THEN: eat bug”. So, since there’s no bug in the web, they just stand still waiting. They’re not complex enough for anything else. This is also why you can swat at a fly, and it will immediately land on you again. The “IF” that’s causing it to land on you hasn’t changed enough for the “THEN” to stop being “land on person”. The implications this all has for more complex life, like humans, is actually pretty unnerving. Welcome to the free will debate, please try to keep your despair to a reasonable level, and have a nice day.


They don’t have a brain (They have small nerve clusters that activates behaviours) and they have no sense of self or any thoughts. Why should it move?


Insects are, for the most part ectotherms. That is they are cold blooded. That means they don’t generate and maintain a constant body temperature. This means that of you cool them down too much they will just stop moving. Spiders in particular are (mostly) ambush predators. This involves a lot of sitting and waiting. I have a friend who keeps tarantulas. Apparently some of them can go for a year and a half without eating. Edit: changed endo the ecto


This was an awesome thread. I learned a lot here. Thanks OP for the question and everyone else for the answers!


Insects are literally just reaction machines. They have no decision making process beyond a pre-programmed set of actions that are prompted by predetermined stimuli. Everything insects do is entirely mechanical, and unless prompted by some external or internal stimulus (threat, environmental change, hunger, mating) they will simply not react.