These large eggs of the Atala butterfly are on the Coontie (Zamia pumila).
The Frosted Elfin lays its eggs only on the Sundail Lupine (Lupinus perennis).
Notice the small parasitic wasp already surveying the butterfly eggs. The young caterpillars will be parasitized by the wasp eggs that she will oviposit.
In a butterfly garden, look for the orange Pipevine Swallowtail eggs on the stems or tendrils of pipevines (Aristolochia spp.)