I went on several accredited bug Id websites, and it is hard to tell the differences, especially when you are pursuing one at a breakneck speed through your garden! Even though the Chinese does get a little bigger, the Carolina does have the ability to grow to a large size, especially the females.All female mantis are bigger than the males. I am no entomologist but I would hazard a guess that far more butterflies are killed by cars, cats, dogs, etc. and suffer death due to their brief life span than are killed by mantises. It might appear that mantises kill a lot of butterflies because you might find a lot of wings in your garden: that would be indicating the mantises are killing butterflies in a particular location: your garden, but I think the numbers of butterflies killed by mantises overall is a lower figure. I think the benefit of mantises are much greater than the risk of losing
butterflies. I observed a medium sized mantis in my cutting garden two
summers ago catching and eating a painted lady, which is a common butterfly in my area. I watched, horrified but yet fascinated as it cut the wings off and ate the body. I watched this mantis for two days then began removing it to another location. It would return to the cosmos, but I was persistent, and it decided to stay away. Mantis are like any predator; they go for the easiest prey. Believe me, it is not easy for a mantis to catch a butterfly! They prefer smaller, slower moving prey. I too grow a lot of fennel
along with parsley and dill for the BSTs. I raised 33 + last summer, and I was able to observe them from the day the eggs were laid until the day they emerged from their chrysalis. I never saw any predation from a mantis, although they are abundant in my garden. As far as I know, BSTs are not in danger from population decline, as the Monarchs are. No self respecting predator would eat a Monarch because of the taste.