What creature is responsible for this? (Pic of droppings)

[PestHate]

Fly would be an obvious one but nothing I searched on Google comes up with red/orange droppings. Really concerned we have some horrible pest in the house!

This is on the double doors to the garden.

Thank you!

Just diffierent types of flys.

Would be very interested in finding this out, as we have exactly the same!

I also found minuscule ones on the floor which was mopped just a couple of days ago. Thinking about it I have seen some fruit flies, maybe it's them.

Spider droppings look like this as do flies

We kept caterpillars that turned into butterflies and when they emerged from the chrysalis/cocoon (not sure of correct term) they pooped out loads of red liquid, it stained the bottom of the enclosure.