Day 424#: Cerulean Chafer Beetle
Today's animal of the day is the Cerulean Chafer Beetle (Hoplia coerulea)!
Photo credit: Anne Sorbes
This absolutely gorgeous species of beetle belongs to the scarab family and can be found in Southwestern European countries, such as France, Spain, and Switzerlands. They prefer somewhat humid environments, such as near swamps or stream. While most people think of the massive rhinoceros beetles or surprisingly strong dung beetles when they think of scarabs, this family of beetles is pretty diverse and contains several subfamilies. The cerulean chafer beetle is part of the Melononthinae subfamily,which includes June beetles, and as such lacks fancy horns and is quite small. However, they're still quite beautiful, and just like their rhinoceros beetle cousins, exhibit some extreme sexual dimorphism. Females are a dull (yet still beautiful) brownish color, while the males are a stunning iridescent blue.
Photo credit: Paul Starosta
Their beautiful coloration makes the males stand out more to predators, and helps them to attract mates since if a male can avoid getting eaten by a bird, rodent, or spider despite not being able to camouflage, then that means he has good skills to pass on to his offspring, and females are more likely to mate with him. Blue is actually a very rare color in nature, and most animals that are blue don't actually have blue pigmentation. In the case of this species, the males are covered in photonic reflective scales, which reflect light to make them appear blue, kind of like blue morpho butterflies. That's also why they look kind of powdery when you look at them up close.
Photo credit: Cristobal Jimenez
Like other types of beetles, they begin life as a larva living within the soil and feeding on roots, buried seeds, and various types of decaying organic matter. Most of this beetle's life is actually spent in their larval stage, and it can spend a year or two underground as a grub. Once they're ready to mature, they'll transform into a pupa and then into their adult form, which only lasts between 3 and 6 weeks. Once they're adults, their diet changes to leaves, flowers, pollen, fruit, and decaying wood, and they'll soon begin searching for a mate. Both sexes will begin congregating in the trees, usually around on that's a food source, in hopes of finding a mate. While most species within the Melolonthinae subfamily are nocturnal, this species seems to be most active during the day, probably since they feed on pollen and most flowers only bloom during the day.
Photo credit: Goliathus on BeetleForum.net
These beetles and their grubs are harmless to humans, but they are sometimes considered mild garden pests since too many grubs feeding on the roots of the same plant can make it sick and possibly die. However, they're not super harmful in small numbers, and since they're so beautiful, I think they should be allowed to cause mild inconveniences.