Second instar

I found this shieldbug nymph in the wild garden this morning, hanging out in a clump of pendulous sedge by the pond. It's a Red-legged Shieldbug (Pentatoma rufipes), which is unusual among British Shieldbugs in that it overwinters not as an adult but as a second-instar nymph. 

A shieldbug hatchling is referred to as first-instar during its first period of growth and development after emerging from the egg, and the instar number increases with each subsequent moult, so this little guy has moulted just once since hatching out. It won't develop any further until it comes out of hibernation next spring, but will then eat voraciously and grow rapidly, and by the time it reaches its fifth or final instar stage, in about June, it will have taken on a similar shape to an adult Red-legged Shieldbug. I captured a fifth-instar nymph together with a newly moulted adult in this photo (and twenty four hours later the second nymph also eclosed, as you can see here).

Because it's chosen to shelter in the sedge clump next to the wildlife pond, I'm tempted to think that this little nymph might be an offspring of the adult I photographed on emergent vegetation there back in September - though I never saw any eggs in the vicinity, so there's really no evidence to back up my fantasy. Nonetheless, its appearance shows that Red-legged Shieldbugs have bred in the garden this year, and that in itself makes me happy.