Doug Tallamy probably would have relieved my curiosity. He would have explained that I rarely saw caterpillars because I wasn’t searching in the right places. Pennsylvania and New York butterfly caterpillars live on their hostplants. Want to see them? Then you must search for them in the right time, on their hostplants. When Cathy at Sylvan Natives Nursery in Pittsburgh put me on to Tallamy’s book, my horizons busted open: Caterpillars live on and feed on their hostplants, e.g., Monarch caterpillars’ hostplants are the milkweed plants, and Red Admirals’ are nettles.
I just never saw many caterpillars up until July 2017. Butterfly numbers north of the Mason-Dixon Line never exceed a few here and a few there.
When I relocated to Georgia, I planted hostplants in my new garden. Milkweeds for Monarchs; Sassafrass for Swallowtails; Passionflower vines for Gulf fritillaries; Hercules club for Giant swallowtails; Hop trees for those same Giants; Hackberry for the Hackberry butterflies; Spicebush for Spicebush swallowtails; Parsley and Rue for Black swallowtails . . . and several I Hope! – I Hope! – I Hope! plantings of Alabama Crotons for Goatweed Leafwings; Atlantic White Cedar for specials Juniper hairstreaks; Pearly everlastings for Painted Ladies; Pawpaws for Zebra swallowtails and Black Willows for Viceroy butterflies.
What I am able to report now, is that caterpillar numbers can be high, dramatically high here in the Southern USA. I’ve had satisfying numbers of Gulf fritillary caterpillar cats ( shown here on passionflower ) as well as good numbers of Giant swallowtail and Monarch caterpillars. Others that showed include Spicebush swallowtails; Black swallowtails and a single Variegated fritillary caterpillar.
These Gulf fritillary caterpillars were seen by the dozens, and they strip the passionflowers vine until there’s not a single leaf left.
Caterpillars in the southeastern states thrive, and they just thrill this young butterfly fan, daily.