Strontium (Sr) was investigated as an elemental marker for the pink bollworm (PBW), Pectinophora gossyriella (Saunders) for movement and dispersal studies. It was applied to cotton either as a systemic (to soil around roots) or as a foliar spray at molar concentrations of 0.1, 0.2, and 0.4 M. Pink bollworms were reared on treated cotton plants during the times of Sr application and for one to five weeks after treatment. Pink bollworms were significantly marked (above 3 s.d. of control mean or above upper value of control range) in a range of 91.7 to 93.8 % during the 8-week Sr application period and from 42.9 to 71.4 up to five weeks after. Strontium appears to be suitable for use as a labeling element for PBW if care is taken to determine indigenous levels (plant and insect) and to use a high enough application rate to distribute the element in the cotton plants.