These insects are among the most popular insects kept as pets, due largely to their unique appearance and the relative ease of caring for them. The care of the various species depends on their native environment (i.e. humidity, temperature, and food sources). The key to keeping stick insects in captivity is to try to mimic the conditions they would naturally experience and feed them foliage as close to what they naturally eat as possible. Stick insects can be handled and can be quite tame, but they are fragile and must be handled with the utmost of care. The caresheet linked below applies to the Indian stick insect, sometimes also called the laboratory or common stick insect, which is quite commonly kept in Europe.
Stick Insects as Agricultural Pests
Non-native Stick insects should never be released into the wild due to the risk that they could reproduce and cause damage to an ecosystem where they are not normally found - non native species are considered plant pests. This includes making sure any eggs are disposed of as well, by crushing, boiling, or burning, as no special care is needed for many species' eggs to hatch. If you are in the United States or Canada, tropical species such as the Indian Walking sticks are considered plant pest and a permit (United Stated Department of Agriculture or Canadian Food Inspection Agency) is required to import them (and be granted only to secure instutions. In other areas, check with the appropriate government agency about legality (e.g. a Department of Agriculture or similar agency).