GRAPELEAF SKELETONIZER

Adult Grapeleaf Skeletonizer

The joys of gardening do not include the abundance of garden pests that infect and infest various parts of my garden. Every time I encounter a new problem, I'm driven to the internet to research similar symptoms, pictures, insects, larvae, etc. Since I am new to gardening, every pest situation is, well, new to me.

The lovely grapeleaf skeletonizer, just one of the new little pests that I've encountered, appeared a couple months ago in the adult form of the moth. I was out in the back garden by the grapes with Sean one evening and said, "I wonder what kind of insect that is. I've never seen a metallic bluish moth before, but it doesn't quite look like a normal moth. Huh."

It started out with just a few here and there fluttering around my beautiful green grape leaves. I looked at the grapes, and they appeared to be unharmed by this interesting metallic blue black flying creature. As the weeks progressed, I noticed more and more of the metallic blue flying moth-like insects flying around the grapes, but they just appeared to land on the grapes. I didn't really think much of it.

I didn't really think much of it.

Seriously, Kelly?

Ignorance is rarely ever bliss in the long run. And this, sadly, is one of those occasions that didn't end well...

One might ask me, "At what point did you realize you had a serious problem?"

I wish I could say, "When I first noticed the strange metallic bluish moth-like insect." But, no.

I wish I could say, "When I noticed dozens of the strange metallic bluish moth-like insects." But, no, again.

I wish I could say, "When I noticed the grape leaves starting to turn brown and paper thin with just their skeletons left." Alas, the answer is still a resounding no.

I didn't really think much of it.

Perhaps this is what grape leaves look like in the heat of the summer months. It was nearing mid to end June when I noticed the grape leaves starting to turn brown and paper thin with several just remaining with their skeletons. We do live in Las Vegas and it happens to be summer, so I didn't really think much of it.

Grapeleaf Skeletonizer Larvae

Until yesterday. I was walking under the archway of the grapes. "Wow, so many leaves are brown, paper thin and wafer thin," I thought to myself. I casually turned a leaf over and saw a plump little caterpillar with yellow, gray and black markings. I plucked off the leaf that had the caterpillar, placed them both inside a Tupperware container and sat down at the computer. Research.

It didn't take long to realize I had a problem. The Grapeleaf Skeletonizer was definitely this cool looking caterpillar inside my Tupperware container. The metallic bluish greenish black western grapeleaf skeletonizer moths fly during the day and are the adult form of the western grapefleaf skeletonizer. They do no damage themselves to the grape leaves but lay their eggs on the grape leaves. After the eggs hatch, the larvae feed side by side on the underside of the grape leaves. There are five different stages of larvae as they mature. Then they crawl under loose bark or into the ground litter (which is plentiful under and around our grape leaves) and spin a cocoon to pupate.

The grapeleaf skeletonizer larvae damage the grape leaves by eating them away so that only the veins remain with a paper thin brownish leaf. This leads to problems with grapes maturing, sunburn of the fruit and overall quality loss and weakening of the vine. The grapeleaf skeletonizer larvae also have poisonous long black spines which can cause skin welts when plucking them off, so wear gloves and don't let them brush your skin.

"I don't have time for this today," I sighed. A busy day didn't allow me an opportunity to deal with my problem yesterday, so this morning I arose early, traded my morning run for caterpillar hunting, put on my thickest garden gloves and grabbed a 5 gallon bucket.

It didn't take long for me to realize my little 5 gallon bucket was not going to be sufficient. I had to get an empty trash can.

Grapeleaf skeletonizer in various stages of growth. Pictures taken summer 2014 from my grape leaves.

As I began to really look at the grapes, I found hundreds upon hundreds of the grapeleaf skeletonizer in various stages of growth! I stopped counting how many leaves I plucked off. I didn't even attempt to count the little creatures. I was in shock. I spent the morning plucking off infected leaves, cutting off entire runners with larvae infecting every leaf, and wishing I had known what the strange metallic bluish moth-like insects were two months ago.

For our family home evening "activity" I enlisted more forces! 

My kids and their friends grape skeletonizer hunting.

Fortunately, I was able to identify the problem and will be on guard next year. In our efforts tonight to find and remove as many of the grapeleaf skeletonizers as possible, we also discovered that our grape leaves are infested with what we believe are grape leafhoppers. I thought, at first, they were white flies. However, after comparing pictures online, I am more inclined to go with grape leafhopper. In fact, the grape leafhoppers appear to be far more plentiful than the grape skeletonizers and have caused just as much damage.

Grape leafhopper and damage to grape leaves.

Leafhoppers are among the sucking insects that damage plants by sucking the juices from plant tissues and leaves. The leaves become yellow, wilted, deformed and may eventually die. According to several university agricultural websites, they also transmit disease. What I thought was perhaps just sunscalded grape leaves were in actuality leaves that have had the juices sucked out of them by leafhoppers. There are very few unaffected grape leaves remaining, and you can see the difference in the picture below.

Healthy grape leaves along side damaged leaves from grape leafhoppers.

I like to try the least invasive means of ridding garden pests as my first line of defense. While wearing gloves, I physically plucked off as many of the grapeleaf skeletonizers that I could find (with the help of my own reinforcements). After the sun went down, I hosed off as many of the grape leaves that I could. I let the leaves dry and then sprayed them with a Neem Oil solution I picked up at the local nursery. I made sure to spray both the tops and bottoms of the leaves. I've been told by other gardeners that you never want to spray your plants with water, in the heat of the summer, during the day (much less any type of solution) lest they burn your leaves. Thus, I waited until after sunset to hose them down and spray with Neem Oil.