Releasing Mantises in the Wild

A lot of you seem to be able to find wild mantises and ootheca in your backyards and wooded areas nearby but I have yet to see a single one and I've been looking for the last few months for the new ones this season to come out...but nothing. I live in a relatively warm part of the country, the temps don't usually get anywhere close to freezing here (we joke we don't have seasons) but this winter was unusually cold, we even had several inches of snow in December and many cold fronts with freezing temps all the way into April, super unusual. I was thinking maybe the unusually cold winter could have killed off a large majority of the native mantids. However, after doing some research I found the most common mantis for this area is Stagmomantus carolina, which needs a diapause to develop. I am a bit confused here, besides being native to North America they are also native to more tropical areas in Central & South America where they wouldn't really get a diapause. Here in Texas at most we get one or two cold fronts that last maybe a few days and bring the temps down to 40 to 50 degrees F.  We are used to having 70+ degree weather pretty much all winter. I'm guessing they manage somehow. What are the usual months for wild Stagmomantus carolina hatching? Is it just too early in the season to see them?

I was thinking about buying some Carolina mantis ootheca to supplement the area with native species regardless. Will I still need to diapause them? I am assuming yes because the ooth will probably not come from a tropical area.