Tiny robots programmed to act like roaches were able to blend into cockroach society, according to researchers studying the collective behaviour of insects.

Cockroaches tend to self-organize into leaderless groups, seeming to reach consensus on where to rest together.

For example, when provided two similar shelters, most of the group tended to gather under the same one.

Hoping to learn more about this behaviour, researchers led by Jose Halloy at the Free University of Brussels designed small robots programmed to act like a cockroach.

The robots didn't look like the insects and at first the roaches fled from them, but after the scientists coated the robots with pheromones that made them smell like roaches, the machines were accepted into the group, nesting together with the insects.

Given a choice, roaches generally prefer a darker place and the robots were programmed to do the same.

When given a choice of a darker or lighter shelter, 75 per cent of the cockroaches and 85 per cent of the robots gathered under the darker one.

Then, to see if the robots had really become part of society and could influence group decisions, Halloy and colleagues programmed them to prefer shelters with more light.

The result? The lighter shelter was preferred by the mixed group 61 per cent of the time, while the cockroaches alone picked it only 27 per cent of the time.

On the other hand, in 39 per cent of cases, the robots, despite being programmed to prefer a lighter shelter, joined the cockroaches under the darker one.

The findings were reported in Friday's issue of the journal Science.