Praying Mantis Care Lifespan, Growth and Molting Mis-molting

Growth- and Lifespan Growth- and Lifespan depends on temperature and the amount of feed. A cooler climate leads to a slower development and a longer lifespan of the nymphs, as well as a lack of feed. Sometimes a further larva state is interposed if the lack of feed is intense. Thus the growth span can be retarded strongly. Therefore you can retard the growth of male nymphs, which often need 1- 2 molts less than females.
Growth The larva-states are mentioned as "Lx", the "x" stands for the number of the actual molting-state. At the hatching the nymphs are named as L1 (until yet no molting). Shortly after the hatch, the nymphs molt for the first time, so they are "L2". Thus a freshly hatched "ready" nymph is named as "L2". Every molting increases the number. So a "L5"-nymph has molted 4 times.

Mantids have a compact chitin-carapace, the exoskeleton which can not grow. Thus mantids have to molt to grow. The first molting occurs at the hatching, the last before the sexual maturity. Between those several molts are necessary, during which the larva grows bit by bit.
The molting-procedure is always the same. Just the last molting to the imago differs. All mantids molt headfirst, exceptional some rare species like Eremiaphila sp.

The molt or 'morph' is triggered by hormones. The mantid stops eating, (sometimes days) before. Shortly before, it search's for a place to hang headfirst, like a perch or the top of the terrarium. The molting-process start with "pumping"  the abdomen, air is pressed into the body and the old chitin-carapace is "bursts open" at the back. This process can take several hours or even day's, the mantid slips out of it. At first the cervix and head, then the legs and the arms. At last the abdomen follows, though 1/6 of the abdomen remains in the old chitin. This process takes about half an hour.

New and soft pliant chitin-carapace has to harden, after hemolymph and air expands it completely.  The mantid remains with the end of the abdomen in her old carapace, sometimes for hours. When the legs have hardened enough, the mantid pulls itself out of the old skin and hardens at an adequate place. Sometimes this takes several days then, will it starts to eat.
The imaginal-molting is the same up to the point, when the mantid gets complete out of the old skin. Then it searches for a vertical area. Such an area is necessary to unfold the wings by gravitation and by pumping hemolymph into them. This procedure can take several hours.

A wonderful process, this metamorphosis to observe, missing limbs can even regenerate, though It is most important that the mantis is not disturbed while molting. Mis-molts can be deadly.

During the hardening the carapace and the wings fill with color. 
Thus 3 important requirements result for the terrarium and its arrangements:

• areas where the mantids can hang headfirst are required, like mesh at the top of the terrarium or branches etc.
• these ones have to be free to the bottom so that there is enough space for the mantid, at least 2 times "length" of the mantid
• for the imaginal-molting a vertical area is needed, like leaves, vertical branches or a wall of cork
• a quiet and still place for the habitat to sit, away from loud vibration or music or high traffic area

Raise the humidity before an expected molt so to avoid getting stuck and mis-molting. 

Mismolting is disappointing! If molt doesn't go smoothly, a mantis falls or gets stuck it will  likely die or be deformed. Unfortunately it is more common than id like to think. 

 Read more on molting here