Answer: How exciting that your garden is coming to life! I can't tell from your description just what the blue/gray caterpillars might be. Caterpillars are the larvae of either butterflies or moths. We all love butterflies, but moths are generally under appreciated. The only problem is that because they are larvae, they will feed on your plants until they grow large enough to pupate and then turn into adult moths or butterflies. If you have lots of plants you may not mind their feeding. If you have only a few plants, their feeding might cause some real damage. You can handpick them and set them somewhere else other than on your plants, or you can allow them to feed on your plants. Or, you can kill them with Bt (bacillus thuringensis), sold as Dipel in garden centers. It affects only caterpillars and does not harm other insects. The choice is yours. Enjoy your garden!
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