Cockroaches Have Personality

German Roach Nymphs
"Baby" German Cockroaches. Courtesy of cdresz from Flickr.com

New research in which scientists studied the behavior of cockroaches has found that – just like humans – each individual cockroach has its own unique character traits. Not only does each cockroach have its own personality, though, each grouping of cockroaches has its own unique personality that overrode the individual – which is one reason individual personalities had not previously been detected.

But, the scientists said, this just may be the key factor in how cockroaches have been able to survive and evolve as a species throughout time.

Because insect behavior is a key attribute in the success of any pest control program, these individual and group personalities can play a key factor in the control of cockroaches.

To study the cockroaches, the scientists attached a minute radio frequency identification chip to each of more than 300 cockroaches by which each insect was individually tracked. The roaches were then divided into groups and the group placed into an “arena” which contained a two shelters, each large enough for the entire group to harbor beneath. The researchers watched each cockroach group for a three-hour interval, studying when and for how long they went beneath the shelter.

From the study, they found that there were shy, or cautious, cockroaches that immediately ran for shelter and stayed there, while bolder cockroaches tended to explore the arena.

But by the end of the time period, every cockroach of the group ended up gathering together under the same shelter. And the behavior of each individual and each group remained the same in every test.

What does all this mean? According to the article in Science Magazine, lead author and behavioral ecologist at the Free University of Brussels Isaac Planas-Sitjà said, “There is a collective dynamic—a social influence—that dilutes the individual personality differences.

So in the group, you end up with a similar behavior in everyone.” So even though the individual cockroaches have different personalities and associated behaviors, they change their behaviors as soon as they’re in a group.

What does the study mean for cockroach evolution?

As explained in an article in The Guardian, “Different personalities are thought to help the survival of the species because by driving different behavior it increases the chances of at least some surviving when disaster strikes.”

What does the study mean for cockroach control?

Each species of cockroach – German cockroaches, American cockroaches, Oriental cockroaches, Brown-banded cockroaches, etc. – can be very different in what they eat, where they like to live (or "harbor"), what they do, and how they breed. Thus, in order to implement control efforts that will be successful, it is critical to understand what is attracting the pest, where its activity is most likely to be located, and how it got in in the first place. Only then can you determine the best way to control it.

But, thankfully, as the study showed, individual cockroaches will follow the pack when they are in a group. So while you will need to understand the behavior and dynamics of a particularly species, you won’t need to understand the personality of every single cockroach in the group.

Additionally, there is one aspect of pest control that is the same for all cockroaches—depriving them of their basic survival needs: food, water, and shelter through cleanliness and sanitation. 

For more information on cockroach control, see Controlling Pests that Pester You. Part 5: Cockroaches and videos at Cockroaches: See How to Control Them.