Insects fed to captive insectivores are deficient in calcium with inverse calcium to phosphorous ratios (Ca:P), and supplementation is required to avoid nutritional metabolic bone disease (NMBD). One method of improving the nutritional value of feeder insects is by ‘dusting’ with powdered supplements, although it is often suggested that these are rapidly shed from prey insects. Here we analysed the calcium content of hatchling, second, fourth and adult instars of black field crickets and silent crickets at increasing time intervals after dusting, as well as comparing three commercially available brands of supplement in fourth instar black field crickets. Our data show these brands do not differ from one another in terms of calcium delivery, despite differences in calcium content. We also show that dusting can be used to increase Ca:P ratios above 1:1 in crickets up to 5.5 hours after dusting, with the exception of adult black field crickets, and thus dusting is a useful method of calcium supplementation.