A mixture of ammonia and alcohol kills bedbugs, according to PestCentral.com. However, the death of these pests occurs when the bedbugs' bodies come into contact with the alcohol. Ammonia is not important for the mixture to work.
When alcohol comes into contact with the bedbug, it kills the insect instantly, explains PestCentral.com. The alcohol works by dehydrating the bedbug. However, it does not continue to kill new bedbugs that walk over dry patches of the mixture. Therefore, spraying the area frequently works only on living bedbugs that come into direct contact with the mixture. In some cases, the solution kills eggs as well.