Any of various substances that interfere with the normal development or growth of insects, some of which are used to control insect pests. The two main categories are distinguished by their modes of action. Juvenile hormone mimics (juvenoids) disrupt the hormonal control of larval development so that metamorphosis either fails to occur or any adults that do emerge are weak and sterile. Examples include fenoxycarb, methoprene, and pyriproxyfen. In contrast, the chitin synthesis inhibitors, such as diflubenzuron and triflumuron, prevent chitin formation and hence normal replacement of the old cuticle following a moult. Treated insects either fail to moult, or have soft weak cuticles that cannot protect them, and die at or soon after ecdysis. Both types of growth regulator have low toxicity for vertebrates, but can have devastating effects on populations of beneficial insects, such as pollinators and pest predators, when used in the field. Their most common applications are to control insects in food stores and in houses.