Tunga penetrans, the Sand Flea, likes to hang out by the water (in the sand).  It’s a tiny little thing and when it doesn’t bite, and it’s on say, your toes, you have no idea it’s even there.  It finds a nice little crevice, perhaps between your nail and your toe and lays a quiet little egg.  Shh!  The baby’s sleeping.  A few days later, your toe itches.  When you go to scratch it, you feel a little pimple.  But when you bend down and look, it’s a writhing black larva wriggling inside your toe.  The fix is to slice the skin open with a razor blade, pop the uninvited parasite out, swab the area with alcohol and then nuke the site from orbit; it’s the only way to be sure.