I do not know that the black pearl was actually attracting the predatory wasps. The guy told me that they did many controlled releases of different beneficial insects throughout the year. I vaguely remember seeing a small packet hanging off the black pearl plants, I am fairly sure that was an egg card like you can buy from many of the vendors that sell beneficials. I will try to look up his email address and see if I can find out the specifics of the black pearl/wasp relationship.