Question

How do you tell if a caterpillar is a boy or girl?

Answer 1

It is nearly impossible to tell if a caterpillar is male, or female. Most species must be dissected to determine gender. However the gender of butterflies and moths can be determined by coloring, like marking on the wings and other characteristics. For instance male monarch butterflies have black spot on their wings that females do not have. 

Answer 2

Well you usully tell by colourings but that is not the case with cateriplars you can not tell by markings like you can with moths. you can sometimes tell by the hair but this only works with some species. sadly you cannot tell that clearly with caterpilars all you can do is weight for them to turn into moths or butterflies hope i helped