Monday, May 10, 2021

What’s This Bug? The Golden Tortoise Beetle.

A close-up of an adult Golden Tortoise Beetles sitting on green leaf
This little bug could easily be mistaken for a sequin that had fallen off some snazzy dress. It has the size, shape, and shininess of a gold sequin, but it’s a Golden Tortoise Beetle (Charidotella sexpunctata). This particular species of beetle is native to the Americas and is most common in states on the East Coast. Lately, however, it has been making headway in the Midwest and down into Texas. Golden Tortoise Beetles are still not super-common and do not congregate in large numbers like many similar beetles, so finding one still has the surprise element for most people.

Two Golden Tortoise Beetle, in metallic and red shades, mating on a white leaf with green veins.
Golden Tortoise Beetles (aka Goldbugs) are not always bright metallic gold in color. They can also be a reddish-brown or a mottled mix of red and gold. Goldbugs have a special ability to change their colors and these color changes are directly related to the mood of the insect. While the metallic color indicates an at-peace bug, when they feel threatened or annoyed their color becomes red. They manage this change by drying up the fluid in their clear exoskeleton (here is an article that explains this with a Panamanian version of the Goldbug). Scientists believe the color change may make the insect appear poisonous to predators, but that reasoning does not explain another situation where they change colors – during mating. When mating, both parties will go from gold to red. Mating appears to be an intense event for Goldbugs; according to this article there have been studies that show that copulation can last nearly ten hours! Apart from some Australian crab spiders that change colors when hunting, Goldbugs seem to be unique in the insect world with this ability to change color at will. 
Golden Tortoise larva on a green stem holding its anal shield high.

The larvae of the Golden Tortoise Beetle have some interesting characteristics of their own. For starters, they look like little dinosaurs; they are flat and reddish or brownish in color with spiky protuberances all over them. Because they are slow and cannot fly, they have developed an effective (and disgusting by human standards) defense mechanism. They make what is called an anal shield by melding together old skin and fecal matter and attaching it to their anal fork (they have an extra-long anal tube for this). They then keep this shield on top of their bodies to protect themselves and every now and then they wave it around. Apparently, predators find this all this as gross as we do and stay away. Watch a larva make and flip its anal shield here.

A Golden Tortoise Beetle sitting on a man's fingertip.There have been limited biological studies done on the Goldbug and the consensus seems to be that this is because they are not a threat to agriculture. Their relativity low numbers and preference for specific plants are the reasons for this. Goldbugs feed primarily on the leaves and flowers of morning glories and sweet potatoes. If they run out of their preferred foods, they may move on to other members of the Convulvulaceae family, but they don’t stray far from that. The damage caused by these beetles is mostly cosmetic and will not lead to long-term problems or crop loss. That being said, you may still want them out of your area. If that’s the case, it is best to remove them manually when they appear. Insecticides are not recommended as the potential for harm to the garden far outweighs the damage Goldbugs can do. If you are maintaining a garden that is well-fed and well-watered, with minimal weeds, you will probably never even see these bugs.

A mean of a man saying, "I love gold".

Adult Golden Tortoise Beetles start appearing in May or June. If you are out there in your garden, keep an eye out for something shiny and take a moment to appreciate this exceptional creature. 

Take care.

Submitted by Pam





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