The efficacy of an extruded plastic trap placed on the ground was measured against plastic-lined trenches used to prevent the colonization of potato fields by walking overwintered Leptinotarsa decemlineata (Say). Laboratory comparisons showed that the original standard extruded trap did not capture as many adult beetles as the plastic-lined trench but that this could be corrected by abrading its surface. Beetles took longer to be trapped by the extruded trap than by the trench and walked away more frequently. The efficacy of the two barriers was unaffected by light simulated rain. Field tests in 1996 and 1997 confirmed that plastic-lined trenches can reduce adult abundance and egg deposition within field even when beetle populations were low. The original extruded trap did not significantly reduce egg deposition. However, it is suggested that a modified extruded trap could be used together with the plastic-lined trench to provide temporary closure of untrenched field sections used for farm equipment access or to surround small fields.