As incredible as it sounds, there are some species of insects that will sacrifice themselves to protect their nests. When faced with an intruder, the Camponotus cylindricus ant of Borneo will grab onto the invader and squeeze itself until it explodes. The ant's abdomen ruptures, releasing a sticky yellow substance that will be lethal for both the defender and the attacker, permanently sticking them together and preventing the attacker from reaching the nest.
Another interesting fact about Camponotus cylindricus ants is that they do not merely protect their immediate surroundings, but also patrol the territory surrounding the nest, sometimes hundreds of yards away.
Other self-sacrificing insects: