The Red-legged Shield Bug (Pentatoma rufipes), also called Forest Bug, is 11-14 mm long.
It is a common and widespread species found in forests (especially oak) and woodlands. Adults are brown with orange legs.
They are partly predatory, sometimes feeding on caterpillars and other insects as well as fruits.
Shield bugs undergo a simple metamorphosis, where the newly hatched juveniles, or nymphs, resemble the adult insects in their shape and vary mainly in size.
While in the nymph stage, shield bugs are flightless and spend most of their time feeding on vegetables and fruits.
As the nymphs grow from late May to August, they change color to include spots or markings, depending on the species of shield bug.

1st & 2nd photo: An adult. Caught in my self made moth trap. In my yard, Hilversum, The Netherlands, 14 August 2018
3rd photo: An adult. Caught in my self made moth trap. In my yard, Hilversum, The Netherlands, 27 July 2019
4th & 5th photo: A nymph. 's Graveland, The Netherlands, 17 June 2014