The answer to 'why is my mosquito scratching sounds' is that the scratching sound is likely caused by mosquitoes biting and feeding on your skin. Mosquitoes use their sharp mouthparts to pierce the skin and draw blood, which can cause an itchy, irritated reaction and a scratching sensation.
This is a common symptom of mosquito bites and is your body's natural response to the saliva the mosquito injects when it feeds. The itchiness and desire to scratch can last for several days after the initial bite.