A xenobiological life form landed on earth. A small pest called anti-matter ant. They are 1g in weight, composed of handwavium matter and can reproduce via fission at a rate given by $2^n$ where n is increased from 0 to infinity, one by one, each time the ant eats his own weight in matter (any matter). It can eat at a rate of 0.001g per second. It poops anti-matter composed of anti-iron atoms. They can convert matter to energy and transmutate it into other elements if needed, but not iron. Iron is turned into anti-matter iron and pooped via their back ends. They are immune to photons. Their back ends have magnetic contention to avoid damage to their internals due matter and anti-matter interacting in their intestines. In the event that there is no matter to eat anymore, they develop intergalatic wings to colonize other planets. When they do this they lose 0.1g of weight. Theres is only one way to kill them : Neutrinos. Unfortunately you need a large flux of neutrinos to kill something. They would die like any normal ant if irradiated with neutrinos. They dont die from old age, assume that as soon as they fission (like bacteria) they produce two new individuals. Assume that a single ant landed on the north pole.
How much time it would take for this ant to destroy earth ?
Is there any way to stop them ? (In other words, are they too overpowered ?)