Congrats Redbaron! Once the wasps know that your garden is a good place to find victims, they'll stick around in following years. I think the key is don't use any broad spectrum insecticides unless absolutely necessary because they kill the good bugs as well as the bad.
Haven't had any parasitized hornworms yet this year myself , but have seen parasitized aphids on tomato plants.
Last year, the wasps took care of all the
aphids and
hormworms for me.