You would think that after having been around for 350 million years or so, there would be nothing left to learn about the cockroach (Blattodea order). Not so. Scientists study them all the time. They study their taxonomy, biology and ecology. They observe how they act and what they eat. Researchers look at their genitalia, anal plates and abdomens.
One study conducted in 2007 by researchers at Vanderbilt University focused on how the bugs learned. Researchers taught individual cockroaches to prefer peppermint, which the bugs normally hate, over vanilla, which they normally like. Scientists trained the insects during a 24-hour cycle. They learned that those trained at night had better memories than those trained in the morning. Scientists determined that the cockroach's memory is closely linked to its circadian cycle, more commonly known as a biological clock [source: Vanderbilt University]. Another study discovered that when isolated, cockroaches became shut-ins. They liked to stay at home. They also ate less and couldn't tell when a female wanted to mate [source: Lihoreau et al.].