Imaginary bees in the bath?

My toddler has developed a fear of imaginary bees in the bath (and more recently in their bedroom). I'm talking full freak out with hyperventilating. Normally they are fine with bees and insects, just a bit wary if they get too close. I've tried introducing a net to 'catch' them and have been showing them pictures of insects, but none of this seems to be working.

Has anyone got any experience of this or any words of wisdom?