I was in Pamber Forest near Basingstoke and Tim was at West Down,Chilbolton near Stockbridge.
It is about time to go looking for these small larvae as the Foxglove Digitalis purpurea starts losing some of the flower bells from the bottom of the main flower stem exposing the tell tell signs of the target species.
So what are you looking for? Below is the described Foxglove with missing "Bells" up to two thrids of the main stem but about a foot off the ground can be seen what looks like a withered "Bell" that is likely to drop any moment.
The Foxglove larva has entered a fresh Bell through one side and has sealed off the Bell using silk where it will feed on the stigma of the flower as well as unripened seeds before moving on to the next flower Bell before it dies,eventually exiting a Bell to pupate just below the soil, where it overwinters.