Two close-up shots of a female Green dock beetle (Gastrophysa viridula), showing off her metallic shimmer, which can be gold green, blue, purple, violet, or red (depending on the light).
Why the name “dock” beetle? Because they mainly feed on dock and green sorrel. This makes them natural biological controllers and an ally to organic farmers (and an enemy of gardeners, as rhubarb is a dock plant).
How do I know it’s a female? Firstly, because she’s bigger (7 mm) than a male (~ 4 mm). Secondly, because she’s heavily pregnant! In the second picture, you can see that it looks like the her clothes are several sizes too small for her body, she’s so big that the wing cases have been totally displaced. She’s about to lay 1,000 eggs (yikes) that look like tiny rugby balls. More info & pictures in this blog post here.