Suggested idea, theories, but not proven are:
Lactic Acid- found in human sweat.
Octanal- found in human sweat.
CO2- what mammals and birds exhale.
These are largely sold in chemical cartridges and propane tanks.
Global Guardian does not rely on propane tanks, chemical cartridges or any other added attractants to be effective. It does however come with a bait tray if you choose to experiment with attractants. There are many natural products recognized to attract mosquitoes.
Assorted fruit (imitates nectar)
Dirty socks (imitates lactic acid)
Baking soda/vinegar (imitates CO2)
Sugar/yeast (imitates CO2)
Limberger cheese (imitates lactic acid)