Forest shieldbug nymph

No it is a nymph till it is adult. It is immature or naive when referring to mammals, birds etc possibly. But when talking about insects the term for a young insect is nymph. Any of the instars up to adult are called nymphs. The instar number changes as the animal grows to indicate how developed the animal is but it remains a nymph. Many insects go through complete metamorphosis in which the nymph/larvae are clearly different to the adult but there are also many that go through what is known as incomplete metamorphosis. This usually involves the animal looking similar to the adult when newly hatched. They then develop through stages until they are adult. The stages leading up to the animal being adult are all nymphal stages. Hope this helps. :)

They change as they age. Look at this link for a late instar nymph of the green shieldbug. It shows how similar they are to adults but they are still not adult. http://www.flickr.com/photos/chirpy_uk/1421712483/

I am obviously not being clear here. The link below is an adult. The picture above is a nymph ( earlier stage of development). http://www.projectnoah.org/spottings/6017537

Trust me it is the nymph stage of the forest shieldbug. We get lots of them here and I have grown up with them. They are also known as instars. As they grow they get larger and more developed. This is a late instar nymph which is almost adult. Still not adult though as the colour and shape are not quite right yet. :) The link below has another shot of one of these nymphs to compare. http://www.wildlifeweb.co.uk/forum/forum_posts.asp?TID=645

not sure what you mean? It says Nymph in the title.