About 10 years ago, I allowed someone to store their belongings in my garage. I did not stop to think what these belonging harbored. It did not take long, however for me to find out. The items were full of German Cockroaches.
German Roaches are pesky little creatures that multiply like… well… roaches. The old saying where I grew up was that if you saw one, you likely had hundreds. “A female German cockroach carries an egg capsule containing around 40 eggs. She drops the capsule prior to hatching. Development from eggs to adults takes 3-4 months. Cockroaches live up to a year. The female may produce up to eight egg cases in a lifetime; in favorable conditions, it can produce 300-400 offspring.” (wikipedia.org)
My adjoining kitchen immediately became infested and they were venturing forth into other rooms of my house. Having grown up in lower NY I knew that these roaches were difficult to get rid of, and sometimes it seemed like the exterminator brought extra bugs with him. I knew I had to act quickly, even before calling an exterminator.
I searched the internet and found two things. Plug in pest repellants, and a recipe for roach repellant. I immediately ordered the best plug in devices I could find (from QVC) and gathered the ingredients for my potion. The potion included boric acid, which is known to kill and repel insects. They travel through the boric acid dust, which adheres to their legs. When the insects groom themselves, they then ingest the poison, which causes death three to ten days later of starvation and dehydration. The recipe also included cocoa powder, which might as well have been a dinner bell for the critters, and sugar just in case the cocoa did not do the trick. (Equal parts) I mixed these ingredients together and put them behind my heating units, in my cabinets (under temporary shelf liners, and then I covered every inch of my kitchen floor. To make the kitchen usable, purchased a straw mats from Pier 1 and covered the entire floor. I wanted to make sure the bugs could still easily get to the treat I had left them. Then I waited.
About three weeks later, I picked up the mats and swept up a great deal of bugs. Then I called the exterminator. He came, he looked, and he never even sprayed anything. He found a few dead bugs under the shelf liners, which I also had to clean up. He said whatever I had done did the job. He told me to call me back if I ever saw another roach. I lived there for two more years and never did have to call the exterminator back.
So can you just use one method or the other? I doubt it. The plug in pest repellant works to keep the pests from hiding and nesting in the walls. The mixture kills the ones that come into the house instead of fleeing in the other direction.