Babies, babies everywhere

There's me saying only yesterday how quiet the garden is and today I'm surrounded by babies. This adult Blue Tit arrived with 4 chicks on the feeder this morning and shortly after this Robin chick appeared. Then another Blue Tit with just one chick turned up. Then a newly fledged Great Tit turned up without any parents. Then both Woodpeckers arrived and stuffed their beaks with food before flying off into the tree's. So they must have some babies to feed too. A very scruffy looking Jay turned up too but I missed the photo of him. The weather has cooled down a lot so maybe that's what bought them all out of the bushes. Whatever the reason, its wonderful to have a garden full of babies. And if that wasn't enough babies I've found another 50 on my Radishes. Lots of identical little caterpillars munching away. I could have sworn they were not there yesterday and today a whole plant has been eaten by them. At the top of the garden we found this. I've seen them before but I'm not 100% sure whats inside, any ideas?