2 mm.
The best way to tell you the size of a butterfly brain is to compare it to something instead of giving an actual measurement. Their brain is roughly same size as the point of a ball point pen.
butterfly
5inches
They are as big as a halk
Nothing at all, except you have seen a big butterfly. The local ecology must be good for butterflies.
about 2stone
i have not seen a brown butterfly but a big brown moth and am still searching for an answer
Owls eyes would be unsuited for a butterfly, being far to heavy and big for any butterfly to carry.
you put both of your fists together and that is how big your brain is.
Big Brain Wolf happened in 2009.
Big Brain Academy happened in 2005.
The Butterfly Nebula or (Twin Jet, M2-9) has a radius of about 0.7 light years