Be careful when inhaling deeply of the fragrant rose; you might get a tickle from some antennae.
This is the nymph of the speckled bush cricket, Leptophyes punctatissima. They like to hide in the patch of mint growing around the roses, as I mentioned in my post Minty Fresh. Being green with speckles, they are well camouflaged, except when they sit on yellow rose petals.
These nymphs will moult into adults as summer progresses. The males create a chirping song to attract females by rubbing their wings. However, with this species the chirp is not audible to humans.