I love taking photos to the bugs. I found this little one, with an out of ordinary sexual behavior. He opens its abdomen and pulls out those white... horns(?). After the alluring of the female he pulls them back. Do they contain feromons? Is it the white that is appealing?
Who is he?
These look like scuttle flies (family Phoridae); the odd structure is on the female, not the male - it may function in getting the male into position; possibly through a feeding attractant? (Just a guess)