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.

Why all the torque leaves Spirder-Man unfazed

SPIDER- MAN never twists like a helpless mountain climber when he dangles from one of his web lines-and the answer lies in the unique molecular structure of his spider silk, say French scientists.

In addition to be being famously strong, the proteins that make up spider thread have incredible torsional qualities, according to a paper, which appeared on Thursday in Nature, the British weekly science journal.

The threa both damps and resists torsional force, and after it is twisted returns to the same position, like special alloys with socalled shape memory, it says.

A team led by Olivier Emile of the Laser Physics Laboratory at University of Rennes, western France, used a small rod to represent the weight of a spider.

They successively tied the rod to a thread of Kevlar, the strongest synthetic polymer, to an ultra-fine soft copper thread, and to dragline silk from the European garden spider (Araneus diadematus). Each thread was then twisted through an arc of 90 degrees, with the rodsuspended from the bottom.

With the Kevlar, the rod twisted back an forth vigorously in response to the movement of the thread. In contrast, the copper was a good damper, stopping the twisting oscillations quickly. But it became brittle after only a few twists.

Spider silk performed best of all. The suspended rod barely budged after the thread was twisted and, unlike the copper, the silk retained its strength throughout the experiments.

The team found a similarly stellar performer in the nickel-titanium shape-memory alloy nitionl, a thread of which was tested using a weight of 3g.

The difference, though, is that Nitinol is expensive and after being bent and twisted at ambient temperature has to be heated to 90C to recover its original shape.

"By contrast, the spider has evolved a shape memory material that needs no external stimulus for total recovery," say Emile's team, admiringly.

The scientists suspect the no-twist silk evolved to give the spider a protective advantage. By not twisting at the end of his thread like a climber swinging from a rope, an abseiling spider is less conspicuous to predators.

The silk's torsional secret could lie in proteins called poly-L-alanine and poly-L-glycine, say the French team, speculating that the coiled double-helix molecule of DNA, the code of life itself, may also have a tiny torque effect.