Carbon dioxide is used as an anaesthetic. Queens are anaesthetised twice during insemination. Once during the insemination process itself, and once 24 hours either before, or after the insemination. This double anaesthetic ensures that the inseminated queen will start laying a few days after insemination.
Carbon dioxide is available in a range of different sized single use cylinders. As you would expect, the larger the cylinder, the cheaper the gas is per gram, and hence per insemination. However that is only true if any unused gas does not leak away when the equipment is not being used. Finding that a large cylinder is empty the second time you come to use it, because the gas has leaked away, is not cost effective not to mention being very frustrating. To avoid this issue I opted to use small cylinders which hold only 16g of CO2.
I bought a complete kit intended for use with an aquarium comprising a disposable CO2 cylinder, regulator, bubbler and tubes. I also managed to buy a box 20 cylinders on-line for only 50p each which included postage. A single cylinder contains sufficient gas to inseminate several queens, and changing the cylinder should it run out mid way through the process takes just a few seconds.
The regulator fits to the top of the cylinder. From the regulator, a tube runs to the water bubbler. A second tube runs from the bubbler to the II instrument. A wooden block keeps the cylinder upright and provides a convenient mounting point for the bubbler.