Bug of the day — Rainbow scarab beetle
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We’ll be posting new material every day this week, starting right now with this first Bug of the
Day post that you’re reading.
Today’s featured BOTD
is the rainbow scarab, Phanaeus vindex.
This beetle is part of the Scarabaeidae family, which in turn is a division of the Coleoptera order.
The rainbow scarab proves the saying, “you can’t judge a bug by its cover.”
For starters, do you think this bug is a native species or an invasive?
Take a look at this colorful critter – it’s about the size of a seedless green grape, with coloration that includes metallic copper, red, gold and green hues, even a little bit of dark metallic blue if you look closely.
The males have that huge prong-like horn jutting from their heads. Like a rhino, or a dinosaur.
Altogether, the rainbow scarab looks like something Indiana Jones should encounter in a forbidden temple halfway around the world, right?
It does look that way.
But this beetle is as American as apple pie.
Its home range covers the Eastern United States, from New England down to Florida and over to Texas.
Ready for another question?
Do you think the rainbow scarab is a crop pest?
How can we put this politely? Phanaeus vindex is one of Mother Nature’s custodial engineers, helping break down and do away with materials that the rest of us would rather not see, smell or step in, if you get our drift.
They’re dung beetles, in other words.
The adults seek out fresh dung, roll it into balls about the size of a marble, and store dung balls underground as a food source.
According to one study, the rainbow scarab’s favorite dung sources include pigs, possums, dogs, cows, raccoons and horses, in descending order. Which means that you don’t have to live in a farming community to have a shot at seeing these bugs – any subdivision could potentially support a population.
Rainbow scarabs not only eat dung, they use it to provision nests for their future offspring. The females form what are called “brood balls” for reproduction. This activity tends to attract males, who will help finish the brood ball construction and vie for the female’s affections.
Worst first date ever? Only from the human point of view.
Each brood ball is made from dung coated with moist soil, and after the happy couple mates, the female deposits a single egg inside the ball. When the larva emerges, it will subsist on the dung until adulthood and it graduates to eating… oh yeah, more dung.
So, even though the rainbow scarab is pretty, and unquestionably beneficial, the BugWeek Web Team does discourage people from casually picking up wild specimens.
Remember when your mom used to say “don’t touch that, you don’t know where it’s been!”
Well, in this case we pretty much do know.
That being said, rainbow scarabs can get along just fine in captivity, where they’ll eat food with a low gag factor, and make great additions to insect petting zoos. Learn how to maintain a live specimen in your home or classroom here.
You can read more about the rainbow scarab at this Featured Creatures document from the UF/IFAS entomology department –