Aging termites carry suicide packs to keep off attackers, according to a new study published in the journal Science.

A team of researchers studied the termites of species Neocapritermes taracua and found that the aging termites of this group develop blue crystals on their back that carries a chemical, possibly a hemocyanin protein, to defend itself from assailants. The termites develop these blue spots at a point between the thorax and the abdomen.

The proteins on the blue pouches works similar to haemoglobin, wherein they carry oxygen to the blood stream of the insects. They have copper which gives the crystals its blue color. When the crystals burst, the protein mixes with a fluid that is secreted from the salivary gland and become toxic. When a group of invaders attack the Neocapritermes taracua species, the toxic chemical is released killing the predators and the termites also die in the process.

"[Autothysis] is usually a one component system. The defensive secretions are stored in salivary glands, but in these species there is a 'backpack' with two crystals carried outside the body. When the termite bursts, the two mix together, producing the more toxic compounds," BBC quoted Prof Yves Roisin, an evolutionary biologist at Free University of Brussels as saying.

The researchers also tested the toxic efficiency by pouring the chemical on the invaders, and found that the predators either died or got paralyzed. They revealed the blue pouches are developed when the termites become old and are unable to protect their colony using their jaws.

Other younger white termites of the species which do not develop the blue spots also seem to release a fluid when they are threatened by the invaders, but the salivary fluid released is not as toxic and effective as it is when the fluid is mixed with the proteins released from the blue spots.

The experts also noted that the number of blue spots increased as the termites grew much older. While all the termite species use the suicide strategy as a defense, they simply eject the contents from their intestine rather than exploding and releasing the toxic chemical like the Neocapritermes taracua species.

The researchers will further study as to how this particular species of termites developed this behavior