The ankles and feet are one of the most frequent places that mosquitoes bite, largely because there is a dearth of body hair that protects these areas.
For men, body hair protects the legs, arms, and other areas of the body from being bitten by insects. But, usually the tops of the feet and lower ankles are not as well protected.
Another reason why ankles and feet are often the target of mosquitoes is because of their close proximity to the ground, where mosquitoes often reside.
When they are not flying, mosquitoes often are resting grasses and other areas on the ground that we walk through, and the feet and ankles are in closest proximity to these mosquitoes when they are disturbed.
If you have a particular problem with mosquitoes biting your ankles and feet, like I do, I recommend that you spray mosquito repellent on these areas before you venture out to locations that are likely to be infested with mosquitoes.