Communal Colony

I've got a question which I hope is not too basic, but I couldn't get a complete answer from a breeder I asked. I am wondering about population control for mantids, whether in a communal setup or just keeping a line going. So my question is a bit obvious.  If a single female can lay an ootheca of fifty, one hundred or more nymphs, how does one control the numbers?  Is there a high mortality rate for juveniles, or is there some method to address this?  This is my first post outside the introduction section.  So thanks in advance...

The aggressive species of mantis if left in the same enclosure will control their own numbers. Some will start to cannabalize each other at L2, even with plenty food available to them and especially at warmer temperatures. Females are usually more cannabalistic, even as nymphs. Anything smaller or weaker gets picked off. 

Separate them at L2 to avoid this. 30 - 200 + nymphs at a time.  I keep some, sell some and gift some. The rest go into a pollytunnel to free range for pest control and future breeding. Some people cull leftover stock.

Sometimes weaker nymphs will just die in the first weeks or mismolt before L2. 

Thanks for all the great info.  So you let. many loose in the polytunnel, and then actually release some to the environment?  Is this so you can harvest breeding survivors later, as you mentioned this was also for the purpose of breeding?  Are there any species which can survive the cold months in Ireland?! 

 I was actually dreading the possibility of cannibalism being an answer!  But I suppose that's not so surprising for the mantis species, and part of the circle of life.  Anyway, they probably just meld and pass on their consciousness when they eat one another 

I dont release any into the enviroment, no way. When I said free range I mean inside a pollytunnel. I provide cover plants for them then basicly let them take care of themselves. I will drop blue bottle casters and crickets in now and again if food looks low. They can eat plenty and are sometimes too succesful at pest control so need the odd bit of help. The mantis that are left once they reach sub adult are obviously the strongest and are the ones Im using for breeding. So far Im only doing this with tenedora. 

Tenedora ootheca can last our Irish winters in the garage or shed until spring. I doubt the nymphs would. They need constant temperatures of 20°C to hatch and molt. Best not to leave ootheca in the house or they can hatch and get everywhere.