When the preventive methods do not work, and the level of infestation is growing, learn how to kill earwigs with fast-working chemical insecticides. There are a lot of options but focus more on treatments that have the following active ingredients: azadirachtin, diatomaceous earth, bifenthrin, pyrethrins, etc. Usually, they come in the form of a spray, which you should apply near the plants or other areas where their habitat is.