The Grape Leaf Skeletonizer is a type of moth whose larval stage is notorious for wreaking havoc on grapevines. Its scientific name is Harrisina americana, and it can be found in various regions across the United States. These insects are considered a pest due to their destructive feeding habits, which can lead to damaged fruit and even encourage bunch rot in grape bunches.
Adult grape leaf skeletonizer moths are easily recognizable by their black wings and red or orange collar behind their heads. On the other hand, their larvae are known for feeding on the underside of grape leaves, leaving just the veins behind. This skeletal appearance gives the insect its name and makes it easily identifiable.
Considering the potential damage that grape leaf skeletonizers can cause to grapevines, it’s essential for growers and gardeners alike to be aware of their presence and effective methods to control them. Regular treatments for grape pests can help keep these pesky insects in check, ensuring healthy and bountiful grape harvests.
Grape Leaf Skeletonizer Overview
Identification
The grapeleaf skeletonizer (Harrisina americana) is a moth that belongs to the Zygaenidae family within the Lepidoptera order. These moths are characterized by their metallic blue body and black wings1. Adults have an unbroken collar of red or orange behind their black head2. Males and females can be distinguished by their antennae, with males having feathery, comb-like antennae3.
Classification
The family Zygaenidae includes other moth species like:
- Yellow-collared scape moth (Cisseps fulvicollis)
- Virginia ctenucha (Ctenucha virginica)
These species share similarities, but the grapeleaf skeletonizer is unique due to its feeding habits and impact on grapes. A comparison table of these species:
| Species | Body Color | Wing Color | Unique Features |
|---|---|---|---|
| Grapeleaf Skeletonizer | Metallic Blue | Black | Feeds on grape leaves4 |
| Yellow-collared Scape Moth | Black | Black | Yellow collar around its neck5 |
| Virginia Ctenucha | Metallic Blue | Black | Virginia native, daytime flier6 |
Some characteristics of the grapeleaf skeletonizer include7:
- Larvae feed on the underside of grape leaves
- Can cause defoliation and sun-damaged fruit in grapevines
- Larval spines can cause skin welts
Problems caused by grapeleaf skeletonizer in grape cultivation:
Pros:
- None
Cons:
- Defoliation
- Sun-damaged fruit
- Potential for bunch rot
- Skin irritation from larval spines
Life Cycle and Biology
Eggs and Larvae
The life cycle of the Western Grapeleaf Skeletonizer begins with the females laying clusters of lemon-yellow, capsule-shaped eggs on the lower leaf surfaces of grapevines. The hatched larvae feed on grape leaves in groups, leaving the upper surface intact. The defoliation they cause can lead to sun-damaged fruit and eventually to bunch rot.
- Larvae stage examples:
- Young larvae feed on the leaf underside.
- Late-stage larvae skeletonize leaf tissue, leaving large veins.
Pupae and Moths
As the larvae mature, they turn into pupae, which hibernate during the cooler season. The adult Western Grapeleaf Skeletonizer moths emerge from these pupae in early spring to June. These metallic bluish or greenish-black moths have a wingspan of 1 to 1.3 inches and are part of the tiger moth family, different from the butterflies.
- Moth characteristics:
- Body length: about 0.6 inch.
- Males and females have comblike (bipectinate) antennae.
- Unbroken collar of red or orange is behind the black head.
- Tip of the abdomen is expanded and curls upward.
During their life cycle, Western Grapeleaf Skeletonizer moths can infest grapes, grapevines, and even Virginia creeper, posing a threat to grape crops. To manage infestations, Bacillus thuringiensis (a naturally occurring bacterium) can be used against caterpillars of this moth species.
Comparison Table:
| Aspect | Larvae | Moths |
|---|---|---|
| Feeding | On the underside of leaves | Adults do not feed |
| Damage to grapevines | Skeletonize leaf tissue | Lay eggs that produce larvae |
| Appearance | Greenish-yellow | Black wings, red collar |
| Active season | Warmer months | Spring to June |
Signs of Infestation and Damage
Foliage and Skeletonized Leaves
Grape leaf skeletonizers are pests that feed on grape leaves, causing significant damage in vineyards. The early stage larvae of these pests feed in groups on the underside of leaves, leaving the upper surface intact1. The late stage larvae skeletonize leaf tissues, consuming tissues between the veins, leaving large veins intact1. Some notable characteristics of infested leaves include:
- Holes or transparent patches on leaves
- Skeletonized appearance with only the veins remaining
False skeletonizers, such as Phanes aoloithus haydenella and Acoloithus spp., may cause similar damage but can be distinguished from true grape leaf skeletonizers based on their feeding habits and morphology2. Handpicking is one way to control both types of pests3.
Grape Crop Impact
The damage caused by grape leaf skeletonizers can have significant impacts on grape crops. Defoliation can lead to sun-damaged fruit and reduced photosynthesis1. Additionally, feeding on grapes can result in bunch rot1. To summarize the effects on grape crops:
- Sun-damaged fruit due to defoliation
- Bunch rot from the larvae feeding on grapes
Control and Management
Cultural and Mechanical Control
Cultural and mechanical control methods involve altering the environment to reduce the likelihood of grapeleaf skeletonizer infestation. For example:
- Regularly inspect grapevines for signs of damage and remove larvae.
- Handpick larvae in smaller areas for efficient treatment 1.
Biological Control
Biological control refers to the use of living organisms for controlling pests. In the case of grapeleaf skeletonizers, some options include:
- Applying Bacillus thuringiensis (Bt), a bacterium that specifically targets caterpillars 2.
- Encouraging natural predators such as parasitic wasps and birds in the habitat.
Chemical Control
Chemical control methods involve applying pesticides to manage populations of grapeleaf skeletonizers. Integrated pest management practices can help suppress populations while targeting other pests 3. Some options for chemical control are:
- Using Vivando, Prolivo, Sovran, Quintec, and Gatten, which provide excellent control against specific grape diseases 4.
- Applying pre-bloom applications of stylet oil, although caution should be taken as it can cause leaf injury on certain varieties 5.
Pros:
- Effective in reducing grapeleaf skeletonizer populations.
- Integrated pest management practices target other pests as well.
Cons:
- Chemicals may have negative impacts on the environment.
- Pesticides can cause phytotoxicity in some grapevine varieties.
Here’s a comparison table of the different control methods:
| Method | Pros | Cons |
|---|---|---|
| Cultural/Mechanical | Non-toxic and safer for the environment | May not be sufficient for large infestations |
| Biological | Targets specific pests with minimal environmental impact | Limited availability of natural predators |
| Chemical | Highly effective in controlling pests | Potential for negative environmental consequences |
Prevention and Monitoring
Prevention of grapeleaf skeletonizer infestation starts with regular inspection. Handpicking larvae can be effective in small infestations. When dealing with these insects, be cautious of their bristly hairs, which can cause skin rashes.
Monitoring methods help detect grapeleaf skeletonizer populations early on. Adult grapeleaf skeletonizers have a distinct appearance, sporting a two-parted tuft that resembles cat whiskers. Identifying and tracking their presence can aid in timely management efforts.
Some monitoring and prevention methods:
- Handpicking larvae
- Regular inspections
- Monitoring for presence of adult insects
Grapeleaf skeletonizers are part of the grape family. It’s essential to implement prevention and monitoring strategies for the overall health of your grapevines. In some cases, biological control methods can be introduced to target the pest population.
| Prevention Methods | Pros | Cons |
|---|---|---|
| Handpicking | Non-toxic | Labor-intensive |
| Regular Inspection | Early detection | Time-consuming |
| Biological control | Reduces pest population | May affect non-target species |
By integrating these prevention and monitoring strategies, grape growers can effectively manage grapeleaf skeletonizer infestations and maintain the health of their vines.
Bug Control Recommendation Tool
Footnotes
- https://education.mdc.mo.gov/discover-nature/field-guide/grapeleaf-skeletonizer ↩ ↩2 ↩3 ↩4 ↩5
- https://mdc.mo.gov/discover-nature/field-guide/grapeleaf-skeletonizer ↩ ↩2
- https://mdc.mo.gov/discover-nature/field-guide/grapeleaf-skeletonizer ↩ ↩2
- https://entnemdept.ufl.edu/creatures/fruit/grapeleaf_skeletonizer.htm ↩
- https://bugguide.net/node/view/4121 ↩
- https://www.butterfliesandmoths.org/species/Ctenucha-virginica ↩
- https://extension.usu.edu/pests/ipm/ornamental-pest-guide/arthopods/moths/western-grapeleaf-skeletonizer ↩
56 Comments. Leave new
Great site!!!! I have Western Grape Leaf Skeletonizer….How do I get ride of them..anything that eats them? : (
Grapes gettin Got in the AZ sun…please help
Michelle
How wonderful to see these photos! My father and I spent many “bonding” afternoons wiping these little guys off the four grapevines in our Phoenix backyard in the 50s and 60s, but I never knew what they were. Thanks for the memories!
I live in Queen Creek and have vines of my own. While not terribly harmful to your pets those little spines on the caterpillars back will welt you up pretty good if you touch them with anything but your hands.
I used to pick them off by hand and kill them, but when I would accidently touch one I couldn’t see with the back of my forearm, while reaching in for one I did see, they would cause me to itch and produce big welts on my arm.
The sale stuff that makes the leaves unsavory to the critters and like the person posted they ony reallly eat the grape leaves so they eventually die becuase they won’t eat the leaves with the chemical on them. Sorry I don’t remember the name of the stuff I bought.
Thanks for your firsthand information. The urticating hair information is a nice warning for our readers.
Bacillus thuringiensis is the stuff I used. Great for ridding leaves of those suckers. You have to apply at least once a month though because they’ll keep coming back.
I have a photo of a similar moth (different color) on my flickr page that I identified as a Zygaenid Moth. The antenna are identical. This might help direct your search. The photo was taken in Singapore.
http://www.flickr.com/photos/61587929@N06/8515749252/
Thanks David,
We appreciate this and all your other comments. It might take us some time to provide links to all your identifications.
I have a photo of a similar moth (different color) on my flickr page that I identified as a Zygaenid Moth. The antenna are identical. This might help direct your search. The photo was taken in Singapore.
http://www.flickr.com/photos/61587929@N06/8515749252/
Looks like a Forester, similar to some Aussie ones with the metallic body but haven’t seen any here with the wing markings like that though.
Thank Trevor. Karl provided us with a identification and some links.
I once ordered a Dictionary of Etymology from a specialist bookshop and was quiet bemused when they got me to come in and pick up my Dictionary of Entomology. You would think a specialist bookshop would have known the difference.
Thank you for the priceless anecdote. Daniel named the first chapter in his book The Curious World of Bugs ( http://www.amazon.com/Curious-World-Bugs-Mysterious-Remarkable/dp/B0058M7XEQ ) after the near homonyms that deviate slightly in pronunciation.
How do I get rid of.them?
Never seen one before today but I just found one in my kitchen. Im in California. ..is this normal?
Kitchens are not the normal habitat for the Western Grape Leaf Skeletonizer, however, California is within the range of the species.
ARGH! They got me this year. They’re everywhere. My poor grapes…
We feel your loss. We have no plums this year because of the spring weather and the lack of bees during the small window for pollination.
These caterpillars are in my mom and dads grapes in Cathedral City CA. They sting when they get on your skin. Are there any reports of allergic reactions or side effects from them.
HOW CAN I GET RID OF THEM???????
We are sorry, we do not provide extermination advice. According to BugGuide: “CAUTION! black hairs of especially late-instar larvae may cause an allergic reaction.”
Other than handpicking these off to feed our chickens, what is the best way to prevent the western grape leaf skeletonizer from eating all my leaves?
We do not provide extermination advice. Perhaps one of our readers will have experience and they can provide the information.
I have these on my grapevine in New Mexico about 60 miles west of the Texas border. There are too many to pick off!!
Spectracide Malathion Concentrate mixed up in a Hudson pump sprayer. Send all these stinging little, vinyard destroying worms straight down to the hottest part of bug HELL!!! These evil creatures are everywhere. in my house, in my animals feed, everywhere. The Malathion did the trick, and for anyone out there who takes pitty on my choice to exterminate these creatures I say, “You lose thousands of dollars of grapes and feed, while finging them inside your home” then I’ll listen to your whining.
Those little guys sting and bite make big welds and itch like HECK…
We have a lot of these bugs on our grape vine in our back yard here in Goodyear AZ. I went down to Home Depot and picked up a bottle of Ortho Flower, Fruit and Vegetable insect killer. It really works!! I will try and post a picture of the bottle.
We do not endorse extermination products.
Does anyone know how to get ride of these guys? I’ve got 3 grape vines. 1 of them is defoliated 100%. The other 2 just started and they are at 20% defoliated, or so. Would anyone know of the best option to annihilate these uninvited guess in my back yard? We just had our first grapes which we were really proud and happy of, but now – I understand the vine without any leaves will no longer produce the fruit till over a year?!
I would appreciate any input.
Norma
See my peevious comment BT is good for ridding vines of them.
Does anyone know how to get ride of these guys? I’ve got 3 grape vines. 1 of them is defoliated 100%. The other 2 just started and they are at 20% defoliated, or so. Would anyone know of the best option to annihilate these uninvited guess in my back yard? We just had our first grapes which we were really proud and happy of, but now – I understand the vine without any leaves will no longer produce the fruit till over a year?!
I would appreciate any input.
Norma
I have muscodine grapes,with 12 inch brownblack colored worms,stripping the leaves of their greenery,I live in North Florida can you tell me what to use to get rid of the worms.
I have muscodine grapes,with 12 inch brownblack colored worms,stripping the leaves of their greenery,I live in North Florida can you tell me what to use to get rid of the worms.
We don’t offer extermination advice. We can help you try to identify the problem if you send an image using the Ask What’s That Bug? link on our site.
Bingo!!! I was looking forward to some nice bunches to share with the grandkids but most of my buds fell off. Many leaves were being stripped and I saw the larvae. I tried thuricide but it was not effective. I cut off as many infected leaves as I could and sprayed the plants with a dishsoap solution. My fingers are crossed. I dont want to use insecticides as mentioned in other posts but may have to go there if prob persists. Thanks for the posts.
I have these all over my small wine grape vines, how do I get rid of them?
We would recommend hand picking.
hello bug man did you know that the catapillar stage of this grape leef eater does bite or can sting my friend had one bite him and i pulled it of his back ill get my pics and send them to you any how have you heard of any body getting bite by this catapillar be for ill have pic in an hour its on his fhone
That’s them! I thought they were something else when I saw them – and should’ve dealt w/ them when I first saw them, even crawling on the side of the house. These pests (oh! how these lil’ guys can’t be that bad ?) ate up our grapevines in a matter of a day or two! Literally skeletonized leaves, barely any remaining; no grapes! Diatomaceous Earth (DE) doesn’t seem to work. We’ve tried that. I felt bad just leaving them alone. Not again!
Wow, so lucky that I happened upon this when I checked what’s that bug today. I had been searching for this ID for days when I found one myself on Nov 1.
Are you in Maryland as well?
My grapevines in Las Vegas, NV have been stripped clean for the past 3 years by these ugly things. Can I feed them to my 2 ducks without harming the ducks?
To the best of our knowledge, they are not poisonous. The caterpillars have hairs which the ducks might find unpalatable.
We live in Vegas too and the last three years these guys have been everywhere!!! Have you found anything that works to get rid of them?? We tried to catch and get rid of the moths early this year and our grapes have been doing alright however I had to remove about 1/3 of the branches in the last week because the caterpillars are going to town…I got some spray from star nursery but I’m worried about using it around my kids…will the grapes still be edible if I spray them? assuming they survive??
Me too, I’m very allergic to them. How do I get rid of them?
This is what was recommended to me. I haven’t tried it yet. http://www.domyownpestcontrol.com/thuricide-concentrate-p-1566.html?gclid=CjwKEAjw1Iq6BRDY_tK-9OjdmBESJABlzoY7hPl3niopV6B0HgcrL2m0NL_yG6e4t5mRZutEupNGyRoCJynw_wcB
I’ve been getting these since I planted grapes a couple of years ago. I just cut off the leaves that have the most babies (they are usually clustered together in tight pods on the bottoms of leaves at first, so they are fairly easy to find even when they are pinpoint tiny). That seems to control them sufficiently. My friends with chickens say the chickens love them.
How to get rid of the grape leaf skeletonMy grape vine is really looking good , but I notices the little black and yellow bugs just starting to eat my leaves, I need to stop them before they eat my grape vine.
We do not provide extermination advice. We would recommend hand-picking.
BT
I cut off leaves with clusters of caterpillars, and also hand picked em, and probably saved my grapes, but only have 2 vines. Next spring, I’ll be ready with a bug net and capture the adults when I see em. I wonder if they might be capable of re-locating vines in future seasons, or if they are just 100% migratory? Other grapes in our yard show no signs of infestation (for now…).
1week the little suckers took to eat my leaves off my grapes,I live in Nevada south,more rain this year,maybe could be it…..?…used neem oil,next is Murphy oil soap.
Is there a home remedy for getting rid of the worms that eat the grape leaves
In 1983 I lived in a home that had a big privacy wall of approx 12′ ’12’ that was covered in a fruitless Grape Leaf Vine. It was thick and beautigul. We had heard the wine and table grape growers in our area were battling the bug but did not realize just how damaging they could be. We sawa couple of the beautiful cobalt and nlack winged pests fly into our yard. However long it took for gestatiin, we could hear the hatchlings crunching away. Within 24 hrs our beautiful vine was GONE! CONPLETELY GONE! It did grow back the next year but at only about 1/3 the coverage we had before.
I have these and now they have moved onto my cucumber plants I believe. I’m using Seven on everything and Neem Oil. What a pain.
I found these all over my grape vines today. I’m in Southern California near North San Diego.
This is our first encounter with these moths; they completely skeletonize our vine. My question is: will the vine come back next year or is the vine dead?
will these wgls eat a marijuana plant?