The lack of any chemical used to attract Carpenter Bees is the main idea behind the design. Carpenter Bees are inherently lazy. They only drill a hole for their nest because they have to. These traps allow them to think that this task has already been completed for them. After they enter and see that is not the case they will automatically exit the trap where they observe the most light. That is down through the bottom. There is also a larger hole there to accommodate their departure. Once they have dropped down the hole the patent pending trap makes any return to the upper level impossible. This feature allows the trap to be free of any chemicals to attract them so that the only maintenance is occasionally emptying dead bees from the lower bottle.