Swallowtail

I have only one buddleia plant, but fortunately it has grown tall and sturdy. It is on the border with a neighbor, who had an exterminator company come and spray regularly for mosquitoes.  Although I can't be sure, it seems to have diminished the population of butterflies in my yard. That neighbor sold the house a few months ago, and our new neighbor moved in this week after doing a major renovation. So far their work on the house has not included an exterminator.