Several isolates of the recently described bacterial species Chromobacterium phragmitis Blackburn et al. were obtained from water collected from low-salinity tidal marshes in Maryland and Virginia. Bacteria were cultured in a liquid medium and applied to artificial diets in the laboratory. One of two Maryland isolates, IIBBL 113-1, was highly toxic to larvae of the cabbage looper Trichoplusia ni (Hübner) and the diamondback moth, Plutella xylostella (L.). The other Maryland isolate, IIBBL 112-1^T, and the Virginia isolates were less toxic to these species. Maryland isolates were toxic to larvae of the seedcorn maggot Delia platura (Meigen), while a Virginia isolate, IIBBL 274-1, was of intermediate toxicity against D. platura. The C. phragmitis isolate IIBBL 113-1 was toxic to adults of the red flour beetle Tribolium castaneum (Herbst), while other C. phragmitis isolates had no activity against this species.