Drain any areas or containers near your deck that hold standing water. Stagnant water attracts swarms of mosquitoes and will become a breeding ground for more mosquitoes. Prevent water from collecting and becoming stagnant by using fill dirt to build up low areas and flushing items containing water -- like bird baths or pet water bowls -- often.
Clean the gutters surrounding your deck. Gutters trap debris and stagnant water, which is a haven for mosquitoes and their eggs.
Use a product containing bacillus thuringiensis israelensis, or Bti, on bodies of water that can't be drained or flushed, such as swimming pools, fish ponds or ornamental fountains. The Bti is consumed by the mosquitoes, and then kills them.
Place fans around your deck and keep them running. Mosquitoes can't maneuver in air currents faster than two miles an hour. The fans will keep away the mosquitoes, and they'll keep you and your deck space cool.
Landscape the lawn and garden area surrounding your deck. Keep grass short and hedges trimmed to help water evaporate and increase sun and wind exposure, all of which helps keep out mosquitoes.
Replace existing light bulbs in deck lighting fixtures with yellow "bug lights" or LED lights. These lights have frequencies that don't attract mosquitoes, unlike some lights.
Install mosquito netting around your deck. The netting is inexpensive and easy to install. It can be installed with a rolling track that surrounds your deck, or the netting can be hung with mounting hooks.