That certainly would be a factor but Tenodera are not everywhere, if Mantis could persist here I think they would still be found in some areas without Tenodera. Perhaps they just haven't made it here yet. Part of the reason for the rampant spread of Tenodera is people buying the ooths and putting them out in their gardens. Are Mantis ooths as widely available for that purpose?Absence in NC is probably because of the pressure from Tenodera species.