Possible Clues:

• 'Forbidden airspace (2,3,4)'
• Sounds like one won't find insect here in restricted area
• Airspace in which (military) planes are forbidden
• Area out of bounds to aircraft
• Exclusion zone where spiders rule?
• Restricted area that's been sprayed with insecticide?
• Sky forbidden to show drama: races have to be broadcast
• Restricted airspace
• Airspace where no aircraft can go
• Area above the National Mall, e.g