The significance of carbon dioxide
Carbon dioxide (also known as carbonic acid or CO2) is the most important attractant for the majority of blood-sucking insects. The gas is present in the breath of humans and animals. It is only present in minimal amounts of around 0.04 % in the air. Human breath contains about 4 %, and an adult human emits approximately one kilogram of carbon dioxide per day.
Almost all mosquitoes and in particular the species found in Central Europe and other temperate zones (e.g., house mosquitoes or the flood mosquitoes, which also occur in masses) are dependent on carbon dioxide as an attractant. This is the reason why Biogents traps are operated with CO2 here. We use pure carbon dioxide, and combined with optimum application, we can already achieve an attractiveness similar to that of a human with as little as 200 to 500 grams of carbon dioxide per day.
In the BG-Mosquitaire CO2 the carbon dioxide is dispensed from standard gas cylinders (the cylinder can be stored unobtrusively). It is the same gas that is used in the production of beverages in restaurants and other eating and drinking establishments. The carbon dioxide is supplied to the trap through a 5-meter long hose.

Carbon dioxide plays a subordinate role for a few mosquito species that have specialized in human beings
These species especially include those that transmit diseases like malaria, dengue fever, or yellow fever. These mosquitoes recognize humans mostly by their skin odor.
Therefore, the Biogents traps with their visual skills in combination with the synergistic human scent imitation are still ideally suited for capturing these mosquito species without the addition of carbon dioxide. This especially applies to tiger mosquitoes (accordingly, the yellow fever mosquito, Aedes aegypti, or the Asian tiger mosquito, Aedes albopictus), but certain house mosquitoes (especially Culex quinquefasciatus and related species) or a few malaria mosquitoes (Anopheles) as well. Although the use of carbon dioxide can partly increase the capture rate significantly, traps can also be used without it in regions where the gas is hard to obtain.