What caterpillar is this? They are building cocoons along the ceiling edge of my porch/
Franklin County Pennsylvania entomology
This looks to be the poplar tentmaker, Clostera inclusa.
Read more about this caterpillar and its management from Bugwood (https://wiki.bugwood.org/Archive:Poplar/Poplar_tentmaker) and the University of Minnesota (http://cues.cfans.umn.edu/old/Web/190PoplarTentmaker.pdf). Your local Franklin County Penn State Extension agent call also help (https://extension.psu.edu/franklin-county).