Thanks to both of you. I am pretty sure it is a swallowtail because I
have seen several of them (they are beatiful) nearby. I have had a good
experience this year with the 'pillars, otherwise, simply because I
have put the dish of a houseplant pot in each garden, filled with water
(clearly I will continue that. It has also helped a lot with keeping
the birds off the raspberries). The cabbage 'pillars, for example, have
been exterminated (there were many early on, before I tried the water
dish), and I have the best crop in five years. Evidently the
swallowtail bugs are too strong tasting for the birds. I also have
monarchs on the milkweeds, also left alone by the birds.