While looking for lily beetles, I found this female Araniella sp guarding its egg sac. The sac, made of coarse yellow silk threads, was attached to the underside of a leaf, and the female sat on a loose web underneath, where she was also eating an aphid (below). There are two extremely similar species, Araniella cucurbitina and A. opistographa, which can only be identified by inspection of their epigyne. Both are small and bright green, with a red mark over their spinnerets, which can often be seen from underneath. They live in trees and bushes, and are orb weavers, although their webs are quite small.