16 August 2010

Golden Tortoise Beetle on Morning Glory Leaf = Holes all over

We have an insect tolerant garden. When I see tiny holes in soft green leafy plants, I assume beetle, but rarely figure out what kind because beetles move so fast.

More than half of the Morning Glory leaves have these distinctive beetle-holes in them.


Well, this morning, one of the culprits was visible so I could research it and learn about it.



What's that bug says it is Charidotella sexpunctata, sometimes called a Gold Bug. Both the larvae and adults eat the leaves of Morning Glories.

Scarabogram gives more information online - a 1994 article by Louise Kulzer.

The golden tortoise beetle is a stunning, vibrant metallic gold color. It has a magical quality, not only because of the brilliance of its color, but also because the brilliance isn't permanent. Metriona can alter color within a short time period, turning from brilliant gold to a dull, spotty reddish color. The gold color also fades when the insect dies. What controls the color while the insect is alive is an intriguing question, but one for which I have no answer. [The gold color is caused by a thin layer of moisture between the cuticle and an inner layer of the elytra. Apparently the insect is able to voluntarily squeeze this layer, reducing its thickness and eliminating the gold color. This change also occurs involuntarily when the beetle is under moisture stress, and, of course, when it dies.


Tortoise beetles overwinter as adults. In the spring the adults begin to feed, mate, and lay eggs. The larvae emerge and feed through the summer, and pupate in late summer. Adults reportedly emerge in the early fall, feeding until the morning glory gives up the ghost for the current season, and then hunker down among plant debris for the winter. I've only seen tortoise beetles on morning glory, which, in my opinion, is poetic justice. I wonder, however, if in the spring they might use alternate food plants since it takes a while for morning glory to put out many leaves, concentrating as they do on getting those stems out there. Natural history observations would be welcome, fellow Scarabs. Remember as you pass vacant lots to look for morning glory and holes in leaves. And do take a minute to look underneath.


Thanks to What's That Bug and Louise Kulzer.

6 comments:

Trish said...

Thanks for your blog post. It was great to find an answer to my "What is this bug??!"

These are amazing creatures!
I had never seen them before till today!

I just saw several of these on a weedy form on morning glory growing in southwest Michigan. I was tempted to call them "snitch" beetles after the elusive beetle-like thing in Harry Potter's quidditch game. It seems like as soon as you reach for them they are gone!

I'm still trying to figure out where these beetles come from - what part of the world are they native to? Do they get to be a pest or can I happily leave them alone? I don't mind them on the morning glory but i've heard they also like tomato plants. It would be a shame to kill something so beautiful.

Thanks again for sharing your photos and blog post.
Sincerely,
Trish

Molly said...

Hi Trish -
You sound like me: When I see something new in the garden I have to know more about it.

Snitch beetles, indeed!

Here's a terrific article about these golden beauties - written by Todd Murray at http://whatcom.wsu.edu/ag/homehort/pest/GTB.htm

Janette Dengo said...

Hi there....well, I am glad that I am not the only one. LOL I found holes in my potato vine plant at front of the house and also the young lilies are all bitten. Then as I dug through the soft green leaves of the potato vine, I found a little gold beetle. Adorable quite, but honestly so damaging. I put it into a jar & started to Google the little critter. As I twisted the jar to see it's colours it stated to alter the colour & became reddish dull. This is what this species does.... as when they become stressed or "unhappy" they alter their colour. Here is little more on it. http://www.flickr.com/photos/tropicaliving/1728748991/ Thanks so much for your blog. Glad I found it.

Martha said...

Hi Jannette -
So not only are they pretty they change colors and size.

I guess when your goal in life is to eat what other people grow, you need many ways to hide!

Haven't seen the little buggers yet this year but there are plenty of other beetles to battle every day!

Louise2 said...

I have been trying to find a way to get rid of the Golden Tortoise Beetles. They eat the entire plant of my morning glories which are hard to grow up here in northern Michigan. I work hard - get the plants growing - and along come these beetles and eat every leaf. What can I do to get rid of them. They may be pretty, but I squish every one I find. Please help if you can.

Martha Stoodley said...

Hi - Many think we shouldn't have to do anything but keep the weeds pulled. Have you tried that yet?

Check this out - http://ipm.ncsu.edu/AG295/html/tortoise_beetles.htm