The legality of hunting squirrels with an air rifle depends on the state and jurisdiction, as well as the species of squirrel. Crosman publishes a state-by-state guide listing approved species for airgun hunting.
The common squirrel may be hunted with an air rifle in 23 out of 50 states. In Texas, the air rifle must have a muzzle velocity of greater than 600 feet per second. Other species of squirrel are subject to tougher restrictions on airgun hunting. The flying squirrel, for example, may only be hunted in Texas. The red squirrel may only be hunted in Maryland, Michigan, Rhode Island, and South Dakota. Lastly, keep in mind that discharging an air rifle within city limits is illegal in some jurisdictions, notes Field & Stream.