The Collaborative International Dictionary of English v.0.48:

Colorado beetle \Col`o*ra"do bee"tle\ (Zool.)
   A yellowish beetle (Doryphora decemlineata), with ten
   longitudinal, black, dorsal stripes. It has migrated
   eastwards from its original habitat in Colorado, and is very
   destructive to the potato plant; -- called also potato
   beetle and potato bug. See Potato beetle.
   [1913 Webster]

WordNet (r) 3.0 (2006):

Colorado beetle
    n 1: black-and-yellow beetle that feeds in adult and larval
         stages on potato leaves; originally of eastern Rocky
         Mountains; now worldwide [syn: Colorado potato beetle,
         Colorado beetle, potato bug, potato beetle,
         Leptinotarsa decemlineata]