An excellent science fiction
movie series. Features a race of insect-like aliens called Xenomorph
s, which have acidic blood and a collective mentality. They lay eggs like normal insects, but the larvae can only mature into adults by leaping onto a host organism's face and injecting themselves dow into the digestive tract. The adults burrow themselves out of the host, killing it in the process.
Basically, if you have an alien Xenomorph on your planet, your species is doomed.
Not even the Marines were tough enough to face the Xenomorphs in the Aliens movie.