Cockroaches are one of the most common household pests. They can cause allergies and transmit disease. Boric acid is among the best ways to kill roaches and, unlike many insecticides, it has no repelling affect, so roaches return to treated areas repeatedly until they die. Boric acid is deadly to roaches, but the toxicity levels of the substance are too low to cause pets or humans any harm.
Mix equal parts boric acid and flour. Mix the ingredients together well. The flour will attract the roaches and the boric acid will kill them.
Place some of the mixture in jar lids behind appliances and in cabinet corners or anywhere you have seen roach activity. The boric acid mix will get stuck to the legs of roaches and they will carry traces back to the nest where other roaches will eat it and die.
Check your jar lids every 2 to 3 days. Add more boric acid mixture as needed. The mixture retains its potency nearly indefinitely, as long as it stays dry. It may take up to a week to get complete control of roaches since the mixture is slow acting.
Increase the effectiveness of the boric acid mixture by removing any possible food source for the roaches. Do not leave food particles in the sink, on counter tops or floor.
Prevent roaches from entering your home. Seal cracks and crevices with caulk along doors and windows to keep roaches out.