One time I fell into a thorn bush then weeks later after I the bad cut on my hand was healed but it was still itchier than that one spot on a dog’s butt they can’t quite reach. It was driving me nuts, I kept scratching and scratching then out shot a thorn that was almost 2 cms long.
Long gross way to say: Our bodies are really good at homeostasis, it’s why tattoos fade
To put it another way, the mosquito beak won’t stay in your skin for long. A 2 cm thorn that got much deeper and healed over still got pushed out.