Cockroach & Catnip Science Fair Project

This is the time of year when I get asked for science fair project ideas. Here's one for you, based on something I read while writing about catnip chemistry. Catnip and nepetalactone (the substance in catnip that affects cats) are said to be more effective than DEET at repelling cockroaches. If you live someplace where cockroaches are relatively easy to find, which presumably includes the entire southern half of the continental U.S., you can test this for yourself. Catch some test subjects and get some catnip spray (found in pet stores and many grocery stores) and DEET-containing repellent. Spray a sheet of paper with catnip, spray one with DEET, leave a sheet untreated. Label the papers and use them to line the bottom of a container. Add roaches. Record where they end up. I'd move the sheets around between trials, epecially if your container has any shadows, to reduce the risk of accidentally introducing another variable (e.g., light).

That's one way to test the assertion that catnip repells roaches better than DEET. To be honest, I don't know whether or not either DEET or catnip repels roaches. A simpler project is to test one chemical or the other. Spray a sheet of paper; leave a sheet untreated. Place them in the bottom of a container. Where do the roaches go?
If you can't locate cockroaches, consider testing another insect (mosquitoes, flies, etc.). If catnip turns out to be an effective repellent, do you think planting it outside your home would reduce the numbers of insect pests coming inside?

Photo: Dawn M. Turner, morguefile.com