When a nymph is about to molt, you see a crack in the lengthwise line on the back of the insect. Within a day, the color darkens as the new exoskeleton hardens. The newly emerged cockroach usually recycles nutrients by eating the shed exoskeleton.
Nymphs reach maturity in five to ten months, with faster maturation at higher temperatures.
Adults may live for two to three years. Hissing The Madagascan giant hissing roach is notable for its unique ability to produce an audible hiss. In the classroom the hissing response is most often observed when roaches, unaccustomed to being handled, are picked up. This is one of the few defensive behaviors that this harmless insect has to avoid predators. The roach also tucks its small head and antennae under the thorax.