Webs in the Pines

D'Arcy notice these oddly spherical webs in pine trees. Closer examination revealed a nondescript brown spider entering one of the spheres. Since these are spherical, rather than flat, they don't seem to match the webs of the agelinid spiders we often see here in western Wisconsin. I wanted to examine them myself, but when I arrived a couple of days later, the spheres were gone. I wonder if masses of hatchlings made them? 

Photography by D'Arcy Allison-Teasley