Hi there! Myobia musculi is a type of tiny bug called a mite. They live on mice and can sometimes cause problems for the mice.
Imagine you have a really tiny bug on your clothes. That's kind of what the Myobia musculi would look like if you could see them. But they're too small to see with just your eyes.
These mites like to live in the fur of mice. They eat dead skin cells and other things they find there. Sometimes they can cause the mouse to scratch and itch, but usually they don't cause too much trouble.
Scientists like to study Myobia musculi because they can tell us things about the health of the mouse they're living on. But for us regular folks, they're just a tiny bug living on a mouse!