We study the population behavior of a multi-cellular organism, soil nematode Caenorhabditis elegans (C. elegans). Widely regarded as a classic model system for neuroscience, C. elegans provides an excellent tool to study genetics, developmental biology, and neuro-behavioral responses to environments. Instead of zooming in on a single animal, we are interested in the emergent pattern of a colony of C. elegans. We use active matter physics models to understand the features of worm colony pattern formation and develop interfacial microfluidic tools to control the pattern formation dynamics in response to environmental perturbations. Using our fundamental understanding of this biological active colloid system, we aim to design living system-based technologies for environment management and soft robotics.