Tumble flies, as we called them. First encountered when one of my sisters complained A worm came out of my knee.

They lay their eggs on things drying in the sun, like us or dogs or sheets, then the larvae burrow into you or your dog and make a kind of zit that squeezing, or if vaseline is put on it so they (the larvae) can't breathe, makes a worm come out. If left alone, eventually a fly will fly out.

Once mom stopped drying sheets in the sun we rarely got them, but a pediatrician we knew fainted when the salve she put on what she thought were my friend's rash of boils caused a field of worms to emerge, and an embassy party was enlivened by flies bursting out of a woman's cleavage as she had not treated what she thought was a painful rash her bra, sun-dried, had given her.

And every Sunday I sat with our basset hounds, and removed ticks and squoze out tumble flies. We all enjoyed that communning... The things kids think are normal!

https://en.m.wikipedia.org/wiki/Cordylobia_anthropophaga