An activity we have meant to do, but only got around to this year is 'hatching' butterflies. It was incredibly easy. Caterpillars arrived in a little pot and had to be left in the post (our of direct sunlight) until the chrysalis stage, then tranferred to net 'observatory'.
Great excitement when the butterflies emerged :-) They are Painted Ladies......beautiful!
We used a National Trust kit but I actually picked it up in Sainsburys. Says Age 7+ on the box, but much younger children would enjoy watching the butterflies too. If the sun comes out today we'll release ours into the garden.
Next week (19-27 May) is 'Save our Butterflies Week'. Half price membership of Buttefly Conservation until the end of May
http://butterfly-conservation.org/