Can he tell the gender by the size, color or like extremely detailed stuff?
Nature stuff

I know that color is one thing he uses.
I know in one picture another bug guy talked about the color, but also asked for another picture that would show the end of the bug's tail.
I think it is a combination of things. With birds we use size and color and sometimes shape - but mostly color.
I do a lot of nature photography, as well as canoeing, and hiking, and birdwatching.
I am not an expert birder. In my area there are some expeert birders. It is amazing how much they can tell you about an ordinary looking bird you might see outside your window. I consider myself more of a naturalist. I know some about birds, but also know quite a bit about trees, fish, mammals and reptiles in my area. But get this:
During a recent photography workshop I met a man who spots an insect and can often tell you the name of the insect and if it is male or female!! To me that is amazing that he can tell a male bug from a female bug.
Now I see an area of study where I need to spend some time.....