Golden tortoise beetle, Charidotella sexpunctata bicolor (Fabricius) (Coleoptera: Chrysomelidae), disturbed adult (undisturbed adults are golden). Photo by Drees.
Common Name: Tortoise beetle
Scientific Name: Varies
Description: Adults are broadly oval to round and nearly convex in shape with some sculpturing of the surface and the edges broadly expanded. They are green-gold with purple mottling and about 1/4-inch long.
A few related species have similar metallic appearance and may feed on different host plants. The golden tortoise beetle, Charidotella sexpunctata bicolor (Fabricius), is brilliant brassy or greenish-gold in life. When disturbed, the color becomes orange with black spots. The metallic coloration is lost completely in dead specimens, leaving them a dull reddish yellow color. They also are about 1/4-inch long.
Larvae of both species are spiny along the sides and have hook on the end of the abdomen. Larvae may carry fecal material on their back, which helps camouflage them and deter predators and parasites.
Life Cycle: As is characteristic of the family, the larvae and adults may be found on the same host plant. There are multiple generations per year.
A tortoise beetle, Chelymorpha sp. (Coleoptera: Chrysomelidae), larva. Photo by Drees.
Habitat and Food Source(s): This beetle and the larvae feed on foliage of anacua in south Texas; while other tortoise beetles feed on sweet potato and related plants.
Pest Status: Although the tortoise beetle is not considered a pest, the golden tortoise beetle occasionally may be a pest on sweet potatoes.
For additional information, contact your local Texas A&M AgriLife Extension Service agent or search for other state Extension offices.
Literature: Dillon and Dillon 1972.
- Golden Tortoise Beetle Facts
- Golden Tortoise Beetle Physical Description
- Golden Tortoise Beetle Distribution, Habitat, and Ecology
- Species Sharing Its Range
- Tortoise beetle
- Are Beetles Able to Bite?
- Studying the non-target effects of Bt corn pollen on the adult golden tortoise beetles (Charidotella sexpunctata bicolor)
Golden Tortoise Beetle Facts
- Perhaps most notably, the Golden Tortoise Beetle represents a rather incredible looking insect. Further, entomologists presently classify it as a member of the leaf beetle family. Also, this gorgeous natural marvel of Nature remains native to a specific portion of the Northern Hemisphere.
- Fascinatingly, it also developed a very special relationship with certain flora. That’s because the unique invertebrate evolved to feed only on a specific family of plants, the Connolvulaceae. This family includes several species, including morning glories, bindweeds, and sweet potatoes.
- In fact, both the larvae and the adults feed on the foliage of these species exclusively. While not unknown, this characteristic remains uncommon enough to garner great interest among researchers. This case, therefore, makes for a rather fascinating example of coevolution.
- The species does not yet hold a listing by the IUCN on its Red List of Threatened Species. However, many experts consider it to be in danger of extinction. Climate change appears to be its greatest threat. This holds true due to the fact that changing weather patterns threaten to reduce the availability of its native habitat.
Tansy Beetle Goldsmith Beetle
Golden Tortoise Beetle Physical Description
First of all, regardless of its beauty, the gorgeous Golden Tortoise Beetle remains a rather small invertebrate. That statement holds true due to the fact that mature adults only average about 5-7 mm in length. However, unlike many related species, it displays no noticeable degree of the trait of sexual dimorphism.
In color, the awesome insect usually appears as either orange or gold in color. However, the golden hue remains by far the more common of the two color patterns. This greater tendency, therefore, serves as the source of the common name.
Furthermore, the chitin of this beetle typically displays a marvelous metallic sheen. fascinatingly, the external regions lack pigment and remain nearly transparent. The insect also has the ability to change its color to a dull brown. This represents a useful defense mechanism when under threat.
- Kingdom: Animalia
- Phylum: Arthropoda
- Class: Insecta
- Order: Coleoptera
- Family: Chrysomelidae
- Genus: Charidotella
- Species: C. sexpunctata
Golden Tortoise Beetle Distribution, Habitat, and Ecology
The mesmerizingly beautiful Golden Tortoise Beetle only inhabits specific areas within the outer boundaries of North America. These areas of habitation primarily include the eastern and western United States. However, scattered populations also exist in the northern sections of Mexico.
The remarkable invertebrate also remains rather selective of its habitat. As a result of this characteristic, it only inhabits regions rich in sweet potato and related species. Sadly, though, this often brings it into conflict with humans, most specifically farmers. These farmers often view it as a pest.
After mating, the majority females lay their eggs on the underside of leaves. The eggs typically hatch after 4-5 weeks. Then, after a period of several weeks, the larvae turn into pupa. Subsequent to that, after a few weeks more, the pupa becomes the relatively short-lived adult of the species.
Finally, the adults themselves serve as prey for several insects. These predators most often include the tachnid fly and the eulophid wasp. Ladybirds, shield bugs, and damselflies remain among the principal predators of the larvae.
Species Sharing Its Range
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Tortoise beetle, (subfamily Cassidinae), any member of more than 3,000 beetle species that resemble a turtle because of the forward and sideways extensions of the body. Tortoise beetles range between 5 and 12 mm (less than 0.5 inch) in length, and the larvae are spiny. Both adults and larvae of some species are destructive to garden plants and sweet potatoes.
Read More on This Topic coleopteran: Typical life cycle The adult Aspidomorpha furcata, a tortoise beetle of South China, feeds on the leaves of the host plant Ipomoea (sweet potato),…
Tropical tortoise beetles are among the most brilliantly coloured of the subfamily and are used in making jewelry. The pits and grooves covering the South American leaf beetle Desmonota variolosa give it an iridescent green colour with depth resembling that of an emerald. The colouring disappears at death because of the drying and shrinkage that occur, and the dead beetle turns dull brown.
In Panama about half of the species deposit their eggs in masses, and the larvae remain together through pupation. Even as adult beetles, they do not disperse very far; feeding and mating can occur on the same plant that the beetles hatched upon. Because of such sedentary habits and their preference for peripheral foliage, tortoise beetles are predictable and exposed targets for predators and parasites. Some species have evolved strategies to counteract the low survival rate that results. Maternal guarding, a rare behaviour among beetles, is known in four of these species. The female of Acromis sparsa climbs on top of her closely packed brood, defending them from predators such as ants and wasps.
A more bizarre strategy is used by other tortoise beetle larvae, including D. variolosa and the North American argus tortoise beetle (Chelymorpha cassidea). During each molt, the old skin is pushed back and attached to spines at the hind end. The dried and shrunken skins plus extruded feces combine to form an umbrella-like shield that camouflages the larvae. A tortoise beetle of South China, Aspidomorpha furcata, can even erect the shield to discourage an enemy. This beetle and the argus tortoise beetle feed upon sweet potato plants; the argus also feeds on other crops, including cabbage, corn, and strawberry.
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The tortoise beetles belong to the leaf beetle family, Chrysomelidae. This family includes the asparagus beetle, cucumber beetle, potato beetle, and the Colorado potato beetle.
This week’s Ask the Naturalist was sent in by Arlene Nielson from Clayton who happened upon a little speck of treasure in a most unlikely place:
Around five years ago I found a golden metallic beetle in my home once that was exactly like a lady bird beetle. I thought I had broken a piece of gold jewelry and had dropped it on the carpet but when I went to pick it up I found out it was alive! I kept it in an insect carrier for a bit with some leaves and eventually released it outdoors. Can you tell me something about this beetle? I’ve never seen one before.
Several shiny suspects come to mind: The glorious scarab beetle, Chrysina gloriosa, and the sunset-colored golden jewel beetle, Buprestis aurulenta, are both common in California, but neither species looks like a golden ladybird beetle. Most likely this carpet-braving bandit is a tortoise beetle, specifically — you guessed it! — the golden tortoise beetle, Charidotella sexpunctata.
Golden tortoise beetles look similar to lady bird beetles (the Coccinellidae family), but actually belong to the Chrysomelidae, or leaf beetles: a huge family whose 37,000 members can be found munching on plants all over the world.
Tortoise beetles get their funny name from the peculiar structure of their elytra — the hardened wing covers that protect the flying wings in beetles — which have a flattened ridge outlining the body and concealing the head and legs, much like a tortoise. Entomologists suspect this feature allows them to hunker down and tuck in their body parts when under attack from a predator.
The golden tortoise beetle is common in North America and can often be found in backyards on plants such as sweet potato and morning glory.
But golden tortoise beetles aren’t always so golden. In fact, they can change color depending on the season or even their mood using the liquid beneath their transparent shell. Underneath the shell are three layers of cuticle, each covered in tiny nooks and crannies that appear smooth when covered with liquid, and reflect light perfectly like a mirror. But when a golden tortoise beetle is agitated or under attack from a predator, it contracts the spaces between the layers of cuticle and forces liquid out of the grooves — doing away with the iridescence and usually revealing a brownish-orange color.
This sort of rapid color-change is very rare in insects, but also occurs in the Panamanian Tortoise Beetle, and the grasshopper genus Kosciuscola (which changes color in response to ambient temperature).
Golden tortoise beetles also change color depending on the availability of their liquid layer. During drier months the beetles become less lustrous and are more orange and bronze with flashes of iridescence.
Throughout North America, populations of golden tortoise beetles can look quite different, which has led to some confusion and multiple names for the same species. Many individuals also have black spots on the outside of their shell, which adds to their appearance as a golden lady bird beetle.
Dave Kavanaugh, the curator of beetles at the California Academy of Sciences, has seen the many colors of the golden tortoise beetle in the field.
“They are really cool — they can be metallic, red, orange, or even greenish,” he said. “They change colors when they are stressed or disturbed, but they are good when they are golden.” Rachel Diaz-Bastin is a Scientific Illustrator in the Department of Entomology at the California Academy of Sciences.
A bird? A bug? Something strange in the natural world nearby? Ask us and we’ll find the answer!
We amazed you with the first set of seven ridiculous facts about the tortoise beetle in our part one article, and now we have returned with part two! This majestic creature has a myriad of wondrous and mysterious ways about it, and we are here to give you the scoop. To discover the top eight most ridiculous facts about the tortoise beetle, all you have to do is read along!
Number Eight: The Variation
The tortoise beetle can be observed in almost all parts of the world, and usually vary by color in correlation to their location. In Java, they can be seen in earthy colors, like red, orange, and deep gold. The green and black variety is often seen in Indonesia, and the golden version keeps to the United States and Canada.
Number Seven: The Diet
When it comes to dining, these beetles have a taste for many of the plants that we humans like to feed on. They are most often found investing crops of sweet potatoes or morning glory, but have also been observed in cabbage, corn, raspberry bushes, strawberry vines, eggplant, milkweed, and plantain trees.
Number Six: Life of a Tortoise Beetle
The life of a tortoise beetle is a rather simple one. During winter months, they hide away from the cold under bark or leaves. They emerge in the springtime, and feed until mating season. During this time, the female will lay eggs of anywhere from 15-30 baby bugs underneath leaves. Roughly a week later, the larvae will hatch, feed, and pupate to go on creating babies of their own. They repopulate at intense rates, and can produce four generations in a good year.
Number Five: The Damage
The infestation of these insects is rarely a problem, because they don’t do much damage on their own. The real issue of defoliation comes when the species overproduces, which can cause leaves to become holey or skeletonized from being consumed by mass numbers. However, the feeding groups are most often unnoticeably small.
Number Four: Enemies in the Animal Kingdom
Like every other species, this beetle has its fair share of rivals. The most common attackers of the species are wasps and a certain type of fly parasitoid.
Number Three: The Tribes
Tortoise beetles come in a variety of types, shapes, colors, and sizes. They all belong to the main family Cassidini, which is composed of five main tribes with various characteristics. These tribes are the Agroiconota (mottled), Cassida (“crucified”), Charidotella (golden), Coptocycla (green), and Deloyala (green and black).
Number Two: They Can Fly
Like most beetles, this species has hidden flying capabilities that aid in its protection. The flexible shell that encompasses the bug is able to be spread out sideways, revealing the hind and forewings of the majestic creature.
Number One: Lending a Hand
Believe it or not, these special bugs have done more than their part in aiding humans. Because of their leaf-based diet, they are often released to contain the spread of invasive plant species. They have helped us cut down on potentially hindering plants, such a thistle and field bindweed. We hope you enjoyed learning the 15 ridiculous facts about the tortoise beetle.
But hold on a sec. Before you run for your pans and pick axes, we should probably clarify a couple things. One, the hills in question are located in the Hickory Knolls Natural Area, where no digging is allowed. And two, the gold isn’t the precious-metal type, though it is indeed a treasure – especially if you like bugs.
What we’re talking about this week are golden tortoise beetles, Charidotella sexpunctata. As we have in summers past, we once again have discovered these little gems – a fairly common species in our area – hanging out on bindweed, one of the insect’s favored food plants.
Thanks to some built-up fluids and a really neat optical illusion, these beetles look for all the world like drops of gold glistening in the sun.
As I stood there admiring their beauty, I realized that, once again, I was going to miss out on an opportunity to snap a photo of these truly glorious creatures. I did have my phone with me, but its ability to capture tiny things like tortoise beetles (which are about a ¼-inch in length) combined with my own limited photography skills, meant a mental picture was as good as it was going to get.
I consoled myself by giving the beetles a couple of light pokes.
I know, it sounds bad, as if I were taking out my disappointment on some poor defenseless arthropods. But my intent was not to harm them; rather, I just wanted to see the beetles change color.
And, did they! In a flash they transformed from rich metallic gold to a still-shiny, but much less impressive reddish-orange.
Researchers are divided on the purpose behind this behavior. Does it confuse predators? Is it an attempt to mimic ladybugs, which use chemical deterrents to avoid getting eaten?
While the reasons may be murky, the science of how it occurs is not.
The beetle’s normal – or “at rest” – golden hue is created when light reflects off liquid that is held in thin grooves between the layers of the insect’s transparent elytra, or wing covers. But when the beetle is agitated or stressed, it drains the moisture away, revealing an underlying color of ladybug-red, spots optional. The color change also can occur during periods of extreme drought, when the insect might not have an adequate moisture intake, as well as when the insect dies.
Being able to change color is a cool trick, as anyone who’s ever observed it can attest. But this species displays an even more interesting behavior that has no doubt saved the lives of many young beetles over the ages.
As larvae, tortoise beetles are dark in color, with soft, fringed spines along their sides and a two-pronged “anal fork” at the rear of their abdomen. Quite a bit of ornamentation for a young insect no bigger than a collar button. But it gets better.
That forked appendage is good for more than just looks. It’s also a collection device.
You’re probably wondering what, pray tell, might a beetle larva need to collect? The answer is twofold: shed skin and fecal matter.
So now you’re probably wondering … why?
Shed skins and fecal matter, as you might imagine, are distasteful, and generally are regarded as items to avoid. But if you happen to be a helpless beetle larvae, jam-packed with nutrients other creatures might find useful, distasteful is exactly what you want to be.
Over time the shed skin and droppings build up on the fork, arching over the young beetle like an umbrella – a poop parasol, if you will. In theory, it’s a great defense against predators.
But no defense is perfect. (If it were, we’d be overrun with tortoise beetles!)
For example, members of the insect order Hemiptera are equipped with piercing/sucking mouthparts. Picture a dinky, hinged drinking straw permanently attached to a bug’s head and you’ll start to get the idea. While many species use their straws to feed on plant juices, others plunge their predatory probes into animal food sources — such as tortoise beetle larvae.
Piercing, sucking predators notwithstanding, tortoise beetles are still pretty easy to find.
Golden tortoise beetles and their handsome cousins, the mottled tortoise beetles, have a taste for plants in the morning glory family; the clavate tortoise beetle, my personal favorite, hangs out on plants in the tomato family, namely ground cherries, jimsonweed, horse nettle and nightshades. (Why pick one tortoise beetle over another? In a word, charm. The clavate species has spots on its back in the shape of — I swear I’m not making this up — a teddy bear. Talk about being cute as a bug!)
The next time you find yourself shaking your head at the invasive bindweed entwined on your perennials or the nightshade under your shrubs, take a minute to check them over. You might find you have a tiny drop of gold, or even a teddy bear, perched on them thar plants.
Pam Erickson Otto is the manager of nature programs and interpretive services at the Hickory Knolls Discovery Center, a facility of the St. Charles Park District. She can be reached at 630-639-7960 or [email protected] Feedback on this column can be sent to [email protected]
This pretty little molten gold beetle has been doing the rounds of the Internet lately, because not only does it look like nothing else on Earth, but it can also completely change colours. And it’s just as pretty when it does.
This is golden tortoise beetle (Charidotella sexpunctata, previously known as Metriona bicolor), a tiny, metallic North American insect that belongs to the leaf beetle family, Chrysomelidae, which includes flea beetles, asparagus beetles and longhorn beetles. Nicknamed ‘goldenbugs’, golden tortoise beetles grow to around 5.0 to 7.0 mm in length and favour foods such as sweet potato and morning glory.
More than 30 years ago, golden tortoise beetles became the first known insect species with the ability to rapidly change colour during copulation. They also do it when disturbed or agitated by predators. Since then, other species of tortoise beetle, such as the Panamanian tortoise beetle (Charidotella egregia), have been found to do the same. Reversible colour change is extremely rare, but not unheard of in insects – in Australia, male members of the dragonfly genus Austrolestes and the grasshopper genus Kosciuscola can switch from black to a brilliant blue due to changes in temperature. What sets the colour-changing tortoise beetles apart, however, is that the colour change is controlled by them, in response to specific events in their environment, such as being poked by a curious human or stumbling upon a willing mate.
Publishing in The Coleopterists Bulletin in 1979, professor of biology Edward M. Barrows from Georgetown University described the results of his investigation into the mating and colour change of the golden tortoise beetle. Barrows collected a bunch of tortoise beetles from Washington and housed them in petri dishes in his lab, feeding them, breeding them and observing their sexual habits. Not only did he find that golden tortoise beetle copulation could last anywhere between 15 to 583 minutes, but he also observed that they would change colour as quickly as two minutes into it. Those beetles that started off a brilliant gold would turn to a goldish orange with black spots and then to a brownish orange with black spots, and those that started out a duller orange would turn golden. The same changes occurred when Barrows gently applied pressure to the beetles when holding them between his fingers. Other reports have these beetles turning from golden to a shimmering red when copulating or agitated.
The golden tortoise beetle, and some other species in its subfamily, is able to change colours due to an optical illusion. Barrows noted how previous observations of golden tortoise beetle colours from other scientsists were extremely varied, ranging from brownish and purplish to bright orange or gold. “Metriona bicolor sometimes looked greenish gold in the field, and highlights of its colouration are probably related to reflected light from its substrate and other nearby objects. Also, depending on the inclination of the line of vision, the color varies from gold to green or even blue,” he wrote in his paper.
Just how this illusion could be produced was discovered in 2007 by researchers from University of Numar in Belgium, who studied the very similar gold-to-red colour change in the Panamanian tortoise beetle. Using scanning and transmission electron microscopes, they saw that the transparent shell of these beetles contains a three-tier structure, each tier made up of several tightly packed layers covered in patches of nanosized grooves. The tiers run from thickest at the bottom to thinnest at the top, and beneath them sits a layer of liquid red pigment. When the nanogrooves are filled with the red liquid, they give the layers a smooth surface, which perfectly reflects the light to give the Panamania tortoise beetle its metallic golden appearance. When the red fluid is drained from the grooves, in response to a stimulus such as agitation or copulation, it “destroys the optical properties” of the shell, leaving an “unobstructed view of the deeper-lying, pigmented red substrate”, the researchers reported in Physical Review E. It’s likely the way golden tortoise beetles manage to change colour and appear differently depending on the light they are exposed to is related to how Panamanian tortoise beetles do it.
Not much is known about why these beetles change colour the way they do, but Barrows suggested it has to do with defence and/or sexual signalling. He suggested for the beetles that changed from dull and spotty to golden, they could be signalling to the opposite sex that they are ready to mate, as beetles in his experiment that were not mature enough to produce the golden colouration did not mate. He also suggested that the metallic quality of the gold could make them more difficult for birds to see, due to the glare. Barrows also suggested that for the beetles that changed from golden to orange and spotty, they could be mimicking ladybeetles, giving them a ‘safety in numbers’ form of defence, as birds can’t tell the difference. This was even true for the golden tortoise beetles that changed from gold to orange without any spots, because in some habitats, Barrows found them living side by side with the spotless ladybeetle (Cycloneda munda). When he tested a bird in the lab that had never been in contact with either insect before, the bird found the golden tortoise beetles to be delicious, but the spotless ladybeetles to be distasteful, so perhaps this colour change is an example of the Batesian mimicry we see in Heliconius numata butterflies, where one species mimics a different, bad-tasting species to fool predators into leaving them alone.
Oh and did I mention that golden tortoise beetles, as larvae, protect themselves by sticking old skin and faecal matter to their anal forks – otherwise known as faecal parasols – to form a shield? How did something with an anal fork get to be so pretty?
For similary pretty insects, check out Ferris Jabr’s post on translucent jewel caterpillars. They’re incredible.
Are Beetles Able to Bite?
Although rare, beetle bites can occur from the following species: blister beetles, stag beetles and Longhorned beetles.
Blister beetles: These beetles feed on crops and gardens, so human contact is likely. They are also attracted to light, making your patio another area to be cautious of this beetle. When the bite happens, the beetle releases a chemical substance that can cause the skin to blister. The blister usually heals within a few days and causes no permanent damage.
Stag beetles: They are black to dark-brown and have large mandibles. The male does not have enough strength in his jaws to bite, however, the female does. A bite from the female can be painful, but does not normally require any medical treatment.
Longhorned beetles: These beetles are named for their unusually long antennae. Longhorned beetles feed on firewood and timber with a high moisture content. Some species also feed on leaves, nectar and pollen. A bite from this type of beetle may cause considerable pain that could last up to a day or two.
Studying the non-target effects of Bt corn pollen on the adult golden tortoise beetles (Charidotella sexpunctata bicolor)
The registration of transgenic corn with corn rootworm resistance offers a viable alternative to insecticides for managing the most economically important pests of corn. While the transgenic Bacillus thuringiensis (Bt) cry3Bb1 protein in corn is labeled as species-specific to the corn rootworm, Diabrotica virgifera virgifera LeConte (Coleoptera: Chrysomelidae), other transgenic proteins such as N4640-Bt corn have been found to have non-target effects on related insect species. Pest plant species such as bindweed (Ipomoea sp.) utilize corn plants as support in the summer months and are specifically fed upon by the Golden tortoise beetle (Charidotella sexpunctata bicolor Coleoptera: Chrysomelidae). Using pollen from cry3Bb1 corn, corn treated with a traditional spray pesticide and untreated, untransformed corn we tested the potential for non-target effects on adult golden tortoise beetles. Previous studies from our lab indicate that there was no effect on the larvae, but the larvae are less likely to encounter and ingest the pollen than adults.