Swarm Intelligence (SI) inspired routing algorithms have become a research focus in recent years due to their self-organizing nature, which is very suitable to the routing problems in Mobile Ad hoc Networks (MANETs). Network topology information can be collected and updated in a distributed and autonomous way via the local interaction among ant-like agents inspired by SI. In this paper we make a comprehensive survey about various SI inspired routing algorithms for MANETs. These algorithms are explained and compared in detail based on a number of network metrics including packet delivery ratio, delay, routing overhead, delay jitter, goodput and throughput etc. It is our hope that the readers can get some hints for their future research work in the realm of SI inspired routing problems from the discussion and simulation results we provide in this paper.