Glowworm Smarm Optimization (GSO), one of the nature-inspired swarm intelligence algorithms is used for finding solutions to optimization problems. Glowworms emit light to attract its mates and mates choosing the brighter member is the basis for this algorithm. We apply this algorithm in conjunction with traditional multi-threshold image segmentation by Otsu method to arrive at our results. The glowworm selection of mates and the movement of these has been mapped to a scientific algorithm to solve the problem and make multi-level threshold image segmentation a relatively efficient one. This algorithm has been implemented in MATLAB and the results are thus presented.