Order one egg case. A single egg case may hatch between 50 and 200 mantids. Unless you are a commercial farmer or possess more than an acre of land you won't need more than a single egg case. One case will be good for about 3,000 square feet of vegetation.
Your egg should arrive by mail in 7 to ten days. Make sure to get a receipt and order confirmation from the seller in case you fail to receive the egg, or it’s damaged upon arrival.
Remove the egg from its packaging. The surface of the egg case should be slightly sticky. Oils from your hands can damage the egg so only touch it with clean latex or gardening gloves.
Fix the egg case to the side of a leafy plant, preferably outside of direct sunlight. The egg case should hatch in 28 to 45 days. It will be difficult to tell as the baby mantids blend in well with their surroundings. When they first hatch the little mantids will crawl out of the egg case and hang on silk-like threads from the bottom of the case until they dry out. This takes about an hour, after which they disperse.
heres a link to buy the eggs
http://insectlore.stores.yahoo.net/ceforliprmae.html
TIPS:
In dry climates make sure to moisten the egg case once every other day with a spray water bottle. Make sure to use distilled water, as tap water has chlorine in it that will kill the mantids.
Do not use pesticides, fungicides or herbicides in your garden once you've placed a mantis egg case there; they are extremely vulnerable to these harmful chemicals.
If you want to see them hatch and place them in a specific area of the garden, put the egg case in a brown paper bag with the top firmly closed. Staple it shut if you need to. Place the bag in a warm, humid place. In a few weeks you should here the little mantids rustling around inside the bag. But be warned, they will eat each other if no other source of food is immediately available. If your intention is to hatch them this way then make sure you also purchase a full supply of hatchling wingless fruit flies to place in the bag as well.
Praying mantis egg cases should not be kept indoors; if they hatch unexpectedly, you will have an infestation problem.
I have a couple mantis out on my plants and they do a great job, highly recomended