The limit for US flights is 2L total, 500mL per person of "medicinal and toiletry articles" in checked baggage, so a can of bug spray or aerosol sunscreen is a non-issue unless it's HUGE. http://www.faa.gov/about/initiatives/hazmat_safety/

If you need to carry on, 1oz bottles of 98% DEET are easily had, or buy a bigger bottle and repurpose a hotel shampoo bottle. I have a 100mL bottle that's been following me around the world for years and is still nearly half full. A little bit of pure DEET goes a very long way.