July 4th, 2008
One evening last week, just before sunset, I spotted a bead of molten gold on a morning glory leaf in the garden. Closer inspection revealed a mating pair of Golden Tortoise Beetles (Charidotella sexpunctata bicolor). For once, I didn’t have a camera in hand — I was taking vegetable scraps out to the compost heap — so I returned to the house to get one. By the time I returned, the beetles didn’t seem quite so golden. I wondered how that could be. Had I just imagined them to be pure gold and not tinged with red and with a pair of black dots on the elytra (wing covers)?
I checked Stephen Marshall’s Insects: Their Natural History and Diversity to confirm the ID of these beetles and discovered this comment:
The Golden Tortoise Beetle (Charidotella sexpunctata bicolor, often called Metriona bicolor, 5-6mm) changes color from gold to red when excited. Larvae with their protective fecal parasols, are common on Morning Glory (Ipomoea violacea) and related plants. Pinned specimens of these beautiful beetles undergo a one-way transformation from gemlike specimens to drab pinned beetles as they dry out in insect collections.
Interesting and beautiful, no?!