Maybe those cockroaches really are ganging up on you.

Scientists in Beleium and France have uncovered an uncanny ability of cockroach larvae to divide and conquer, at least when it comes to settling down into suitable shelters.

No matter how many havens are available, the insects we love to hate can apparently decide among them selves how best to split up.

Instead of cramming the bulk of the population into one shelter and shielding some at the expense of others, the group divides evenly into a minimum number of lodgings, there by balancing overcrowding with an equitable share of food and safety in numbers.

Such group decision-making has been seen in social insects such as ants, bees and termites, but never before among cockroaches.

According to study co-author Jose Halloy, of the Universite Libre de Bruxelles in Belgium, the cockroach larvae were able to reach a collective decision without any leadership, sophisticated social structure, long distance communication or prior knowledge.

Halloy said in an e-mail that the nocturnal German cockroaches used for the study, appearing in this week's proceedings of the National Academy of Sciences, scurried under the small shelters within a circular arena to seek out safe, dark places.

If 50 roaches could choose between two shelters that held 40 apiece, the group invariably split into two optimally sized groups of about 25. If they could choose among three shelters, the group filled two evenly while leaving the third virtually empty.

Although too early to consider the study's future applications for pest control, Halloy said," we envision the possible design of trap networks," ones that could exploit the roaches'collective behaviour.