An underguard assembly is provided for use with a modular conveyor of a conveyor system. The underguard is formed of a flexible web that hangs beneath the conveyor to catch debris falling from the sides of or through the conveying surface. To support the web, a stiffener rod is placed in an elongate pocket formed along each longitudinal edge. Opposed support assemblies spaced along the sides of the conveyor frame hold the enlarged pocket formed by the stiffener rod. An adjustment means is provided on each support assembly that allows the web to be easily attached and detached from the conveyor frame. Further, the support assemblies adjacent the end of the conveyor are modified to support the web beyond the end of the conveyor. This allows the web of a first modular conveyor to overlap with the web at the start of an adjacent modular conveyor, thereby providing a substantially seamless underguard function for a conveyor system.