Grape Leaf Skeletonizer: All You Need to Know for a Healthy Vineyard

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.

Footnotes

  1. https://education.mdc.mo.gov/discover-nature/field-guide/grapeleaf-skeletonizer 2 3 4 5

  2. https://mdc.mo.gov/discover-nature/field-guide/grapeleaf-skeletonizer 2

  3. https://mdc.mo.gov/discover-nature/field-guide/grapeleaf-skeletonizer 2

  4. https://entnemdept.ufl.edu/creatures/fruit/grapeleaf_skeletonizer.htm

  5. https://bugguide.net/node/view/4121

  6. https://www.butterfliesandmoths.org/species/Ctenucha-virginica

  7. https://extension.usu.edu/pests/ipm/ornamental-pest-guide/arthopods/moths/western-grapeleaf-skeletonizer

Reader Emails

Over the years, our website, whatsthatbug.com has received hundreds of letters and some interesting images asking us about these insects. Scroll down to have a look at some of them.

Letter 1 – Western Grape Leaf Skeletonizer

 

caterpiller
WTB, you guys are wonderfull. I had a question about an Orange Dog a while back @ you guys got back to me right-a-way. Thank-you. I have another Caterpiller I’m curious about. I didn’t see any other pictures of them, so hopefully you’ll get this one I’m sending. (Computer illiterate) I live in Chandler, AZ. ( Phoenix area). Our neighbors have some grape vines growing over our fence. I was very excited that we were going to have fresh grapes until I noticed they were covered by these yellow, black & blue stripped caterpillars. They don’t really seem to be eating the grapes, just the leaves. The plant does seem to be dying however, I don’t know if its from these little guys or just neglect. The one I took a picture of is one of the larger ones. About a 1/2 in. Any-way, what are they? Will they go for any of our other plants, for example, our orange tree? Are they poisonous if eaten by our dogs? Could they be killing the grape vines, & should I be concerned about them? Thanks again,
Cindy

Hi again Cindy,
We have been away and are just catching up on letters. This caterpillar is a Western Grape Leaf Skeletonizer, Harrisina brillians. This is a new caterpillar for our site. They are a major defoliating pest of grapes and will not spread to your other trees. If they are numerous, they will completly strip a vineyard of leaves. This will not kill the vines, but it will not be a good year for grapes. They will not poison your pets.

Letter 2 – Western Grape Leaf Skeletonizers

 

Found on grapevine in Southern AZ
Location: Southern Arizona SE Tucson PIma county
August 3, 2011 3:18 pm
We have an infestation of what seem to be caterpillars. They start out very small and grow to be pretty hearty looking caterpillars with light green/yellow, and purple bands. They are only on the grape vine in the backyard and have not gone to any other plant in the yard. I hate to harm them but they are killing the vine. Any idea what they may be? Thank you!
Signature: Thankful for your time, Ashley Goode

Western Grape Leaf Skeletonizers

Hi Ashley,
We believe you would be justified in removing these Western Grape Leaf Skeletonizers,
Harrisina metallica, from your grape vine.  According to BugGuide:  “Adults emerge and lay eggs on leaves soon after bud-break in spring. Early instars feed gregariously on undersides of leaves which they skeletonize. Later instars spread out and may defoliate entire vineyards. Several generations per year.”

Letter 3 – Western Grape Leaf Skeletonizer: Imago and Caterpillars

 

Beautiful Blue Bug
Sun, May 10, 2009 at 1:44 PM
These blue fellows showed up in late April, proceeded to make a love shack of my grapevines, and disappeared shortly after. A couple of weeks later my vines are covered with these cute, little yellow and black caterpillars. I’m assuming the two are related but I can’t seem to find them on any of the internet searches I’ve done.
Thanks for any info, Rebecca
Mesa, AZ

Western Grape Leaf Skeletonizer
Western Grape Leaf Skeletonizer

Hi Rebecca,
We are so happy to have your photos of the adult moth as well as caterpillars of the Western Grape Leaf Skeletonizer, Harrisina metallica , in the same letter.  According to BugGuide it is:  “Native to southwestern USA and northern Mexico. Occurs from California to Texas, north to Colorado and Utah ” and “Larvae are a severe pest in some California vineyards.”  A very similar species, the Grape Leaf Skeletonizer, Harrisina americana, is found in the eastern U.S.

Western Grape Leaf Skeletonizer Caterpillars
Western Grape Leaf Skeletonizer Caterpillars

Letter 4 – Western Leaf Skeletonizer

 

Blue Flying Insect
Location:  Las Vegas, NV US
September 2, 2010 7:02 pm
I haven’t found this one in any reference I have and have no clue of what it is. I worked around it to pick up the highlights in the body color. Just looking at it normally it was a dark blue to almost purple.
signature:  Steve

Western Grape Leaf Skeletonizer

Hi Steve,
The color on your moth is bordering on ultraviolet.  We believe this must be a Western Grape Leaf Skeletonizer,
Harrisina metallica, though the color on your specimen is so much more vivid than any of the examples posted to BugGuide.

Daniel,
Thank you for the ID.  Yes, the light was perfect in one direction to show the blue.  From any other angle it looked more like your specimens.  It was very patient and stayed around while I set up a tripod and didn’t fly when I changed angles.
Steve

It surely has earned that species name metallica.

Letter 5 – Another Leaf Skeletonizer moth from Maryland

 

orange and black moth in maryland
November 2, 2009
I have liven in Maryland my entire life and have not seen this guy before. there were several dozen flying around the house on halloween and they were gone the next day. I never saw one land but when i forced one to the ground it did not move and i was able to pick it up and hold it without it trying to fly away. it did not try to fly when i set it on the ground or an elevated point, i had to toss it in the air and then it flew just as it had been. the abdomen has several black spots around pores but no hair, the head is black and the wings are black near the body and transparent at the tips.
Richard
Pasadena Maryland

Leaf Skeletonizer Moth
Leaf Skeletonizer Moth

Hi Richard,
WE were very puzzled by another letter we received yesterday with images.  It seems this is an introduced species of Leaf Skeletonizer Moth, Pryeria sinica.  You can read about it on the Invasive Species of Concern in Maryland website.   The website indicates:  “In April and May of both 2001 and 2002, a homeowner in the City of Fairfax, Fairfax County, Virginia, noticed a large infestation of larvae on her ornamental Euonymus (Celastraceae); the larvae were causing significant defoliation of the plants. In May 2002, several larval specimens were sent to the Insect Identification Lab, Department of Entomology, Virginia Tech University, Blacksburg, Virginia for identification. The entomologist there (Eric Day) reared the larvae to adults, which emerged in November. Additional adults were collected at the Fairfax site in December 2002 and submitted to the Insect Identification Lab. Eric forwarded the adults to John Brown at the USDA Systematic Entomological Laboratory (SEL) in March 2003. Based on the available literature, comparison with specimens in the collection of the National Museum of Natural History, and consultation with Dr. Marc Epstein, the specimens were identified as Pryeria sinica Moore (Lepidoptera: Zygaenidae), which previously is unreported from the United States.”

Letter 6 – Bug of the Month November 2013: Euonymus Leaf Notcher Moth

 

Subject: October bug
Location: Pasadena Maryland
October 29, 2013 9:02 pm
Hello,
Every October we get a bunch of the bugs in the files below. They live only in one bush in our yard and lay eggs in the light strands I use for halloween. Would you be able to help me identify them?
Thanks!!
Signature: Carrie

Euonymus Leaf Notcher
Euonymus Leaf Notcher

Hi Carrie,
This moth is appropriately colored for Halloween.  We quickly identified it on BugGuide as a Euonymus Leaf Notcher Moth,
Pryeria sinica, and we learned that it is an invasive species.  Since Euonymus is a common shrub used in landscaping, we expect that this species may begin to spread to other states, though right now it is only reported from Maryland and Virginia.  According to BugGuide:  “Introduced from Asia; first found in MD and VA in 2001; it is spreading.”  Maryland Department of Agriculture lists it as an Invasive Species of Concern in Maryland.  There is an October 2004 update which states:  “Pryeria moths are expected to emerge in November. MDA is attempting to delimit the populations of this emerging pest. Marylanders are asked to contact Dick Bean at MDA (410) 841-2743 if you see pupae now, or moths in late October/November.”  That number might still be valid and we would suggest that you contact the MDA.  Control is probably most effective with the larvae.  Since its emergence is timely and since it is a species of concern, we are featuring your submissions as our Bug of the Month for November 2013.  Thank you for allowing us to provide a valuable public service announcement to notify people of this invasive species.

Letter 7 – Diurnal Leaf Skeletonizing Moth from Vietnam: Phauda flammans

 

Subject: mothID please
Location: Hanoi, Vietnam
June 8, 2015 3:51 am
Guys
While at the Co Loa Citadel, Hanoi, May 2015, I was accosted by this gorgeous moth (and 10,000of his friends). I would really appreciate an ID a bit closer than “One of the Tiger Moth” spp.
Have a great day and keep smiling.
Signature: Fof

Diurnal Leaf Skeletonizing Moth
Diurnal Leaf Skeletonizing Moth

Dear Fof,
Our initial impression was the same as your thought that this is a Tiger Moth, but as we researched, we located a matching image on PhotoBucket identifying the species as
Phauda flammans, and we then located another image on FlickR of a mating pair.  Animal Diversity Web provided us with the family Zygaenidae, which are the Leaf Skeletonizing Moths, though it is actually the caterpillars that skeletonize the leaves.  This is a diurnal species of moth that flies during the day. 

Daniel, g’day
Wow! That was, to put it bluntly, spectacular not only the speed of response, but the ability to hit the nail bang on the head.
Thank you very much for your assistance with this ID.
Have a good day and keep smiling.
Fof

Letter 8 – Bug of the Month November 2015: Euonymus Leaf Notcher

 

Subject: What type of moth?
Location: Central Maryland
November 1, 2015 10:40 am
First time I’ve seen this and I’m a bit perplexed? Maybe a wasp moth although banding doesn’t seem to fit.
It was seen in the morning on Nov 1st in the Baltimore, Md area on a colder rainy day.
Flagellate antennaes, orange body black tail and overall fuzzy. 6 legs and clear wings with black veins and a bright yellow tinge at the attachment point of the wings.
Signature: Steve Sheggrud

Euonymus Leaf Notcher Moth
Euonymus Leaf Notcher Moth

Dear Steve,
That was a good guess, but this is actually an invasive, exotic Euonymus Leaf Notcher Moth,
Pryeria sinica, a species from Asia first detected in Maryland in 2001 according to BugGuide.  We first reported on the Euonymus Leaf Notcher in 2005.  Since sightings of the adult moth are most common late in the fall, and since this is an invasive species that gardeners should know about, we are tagging this as our Bug of the Month for November 2015.

Letter 9 – Euonymus Leaf Notcher Moth

 

Subject:  What’s that bug?
Location:  Virginia
November 3, 2013 11:04:41 AM PST
Dear Bugman,
My husband emailed me this photo of a bug he saw in our yard.  I’ve seen them too, but have no idea what they are.  Can you help us solve the mystery of the fuzzy wasp moth?
Thanks,
A new resident of Virginia

Euonymus Leaf Notcher Moth
Euonymus Leaf Notcher Moth

Dear new resident of Virginia,
Perhaps you didn’t take note of our featured Bug of the Month for November 2013, because if you had, you might have recognized your Euonymus Leaf Notcher Moth, an invasive, exotic species first reported in Maryland in 2001 and first profiled on our site in 2005.  These moths attract attention because they fly in late October and November when few other insects are common.  To the best of our knowledge, the Euonymus Leaf Notcher Moth,
Pryeria sinica, has only spread as far as Maryland and Virgina, though it is expected to expand its range as its preferred larval food plant, Euonymus, is regarded as a significant landscaping plant.  We just returned back to the office after a one week stay with family in Ohio, and we commented to the gardeners in our family that the prevalence of Euonymus in so many gardens might mean that the invasive Euonymus Leaf Notcher Moth would have a plentiful food supply should its range extend further west.  The plants are now a vivid red color and you might check to see if you have any growing in your yard.  If there is a plentiful food supply for the caterpillars, populations can explode and adult moths can be quite numerous.  More information on the Euonymus Leaf Notcher Moth can be found on Invasive Species of Concern in Maryland.  This is our first new posting upon returning to the office after our holiday.

Letter 10 – Probably Grapeleaf Skeletonizer

 

Help identifying unknown caterpillar
Location: Rockledge, FL
November 17, 2010 5:41 pm
While clearing overgrown grape vine within a nature preserve we had found numerous small caterpillars around 0.5 cm in size. They suspend themselves on silk strands when threatened. Can you help in identifying them. We can’t seem to locate them in our books.
Signature: Brandon Smith, Environmental Program Coordinator

Grapeleaf Skeletonizer

Hi Brandon,
Sorry for the delay.  We researched this when you sent the image, but then we got waylayed and never posted the response.  Though the markings are a bit different, we believe this is a Grapeleaf Skeletonizer,
Harrisina americana, which is pictured on BugGuide.

Letter 11 – Probably Western Grapeleaf Skeletonizer

 

Subject: Unusual insect for Vegas
Location: Las Vegas, Nevada
September 15, 2013 5:30 pm
To whom it may concern, I’ve happened across a very unusual insect flying around the outside of my store on September 15th. I’ve never seen anything quite like it before, let alone one that’s gone whizzing past my face just to land long enough to get a shot. Whatever it is, it’s a beautiful little specimen, a quick web search later turned this site up as the first one to ask.
Thank you for your time~
Signature: Ian A.

Western Grapeleaf Skeletonizer
Western Grapeleaf Skeletonizer

Dear Ian,
Because this insect is partially obscured by vegetation in your photo, we cannot be certain, but we believe this is a moth known as the Western Grapeleaf Skeletonizer,
Harrisina metallica.  Are there grapevines nearby?  You can also compare your sighting to the images of the Western Grapeleaf Skeletonizer posted to BugGuide.

Letter 12 – Forester Moth from Taiwan

 

Subject: Re: Metallic blue micro-moth?
Location: Yamingshan National Park, Taiwan
April 7, 2013 5:32 pm
Hello Bugman!
I just returned from a quick trip to Taiwan. I’ve never seen it rain so much, but we managed to get some bugging in between storms. This is a picture of one of the odd ones I can’t seem to find in my books or online. We found this moth (?), which was half an inch long, around mid-day on April 4th on a jungled trail in Yamingshan National Park north of Taipei. The weather alternated between clouds and rain. I was thinking it might be a small geometer moth but I didn’t get a top view before the little guy flittered away into the mists. I appreciate any help you can provide, Bugman.
Thank you so much!
Signature: Marian Lyman Kirst

Unknown Blue Moth from Thailand
Unknown Blue Moth from Taiwan

Dear Marian,
This is sure a pretty little moth, but our initial attempts to identify it have turned up blank.  Perhaps one of our readers will have better luck.

Karl Provides an Identification:
Hi Daniel and Marian:
It looks very similar to the Forrester Moth or Leaf Skeletonizer Moth (Zygaenidae: Procridinae), Clelea sapphirina, from Vietnam posted by Tricia a few months back. It is probably C. formosana, which, as far as I can tell, is the only member of the genus in Taiwan (formerly known as Formosa). Here is a link to a photo of the same species also taken in Yamingshan National Park. Regards.  Karl

Letter 13 – Unknown Mating Moths probably not Arctiids. Likely Leaf Skeletonizers

 

For you Bug-Love collection
Location:  Hue, Vietnam
October 5, 2010 2:56 pm
I was sitting at an open-air cafe in Hue, Vietnam on a sweltering June day, when this mating pair came plummeting drown from a tree and landed at my feet. Sadly, it seems that in their frenzy to procreate, they had died. Any idea what they are? When they fly, they are just a blur of startling red motion. I am also still hoping that you will be able to identify the strange appendage-less bug I submitted for idenification on Oct. 1st.
Signature:  Curious Traveller

Mating Moths

Dear Curious Traveler,
We believe these are Arctiid Moths, commonly called Tiger Moths, but we need to research the species.  Our good friend, Julian Donahue, is an expert in Arctiids, but he is currently traveling, so we need to wait for assistance from him.  Meanwhile, we will post them as unidentified Arctiids and hope we or our readership will get lucky on the internet.  Regarding your other submission, please resend it and include “resubmission:  strange appendage-less bug
” in the subject line.

Julian Donahue Responds
October 9, 2010
Hi Daniel,
Returned from Peru yesterday, and found this reference in “my” Google Alerts.
My first reaction is that these moths appear to be in the family Zygaenidae. If I had aspecimen in hand a quick look at the venation would confirm this.
A more definitive identification will have to wait until my next visit to the Museum, where I can check Barlow’s book on common moths of SE Asia, or even Seitz’s Macrolepidoptera of the World (which includes Zygaenidae).
Stay tuned.
Julian P. Donahue

Letter 14 – Forrester Moth from Viet Nam

 

Subject: Moth with irridescent turquoise markings
Location: Sapa, Vietnam
February 11, 2013 4:15 pm
Dear bugman,
We saw this pretty little moth sitting on a path in a park in Sapa, Vietnam, and are hoping that you can tell us what it is. We have spent many hours combing pages of photographs of fantastically coloured insects, but no luck so far
Signature: Tricia

Forrester Moth

Hi Tricia,
This is the type of identification that might take considerable research, and we are going to post it as unidentified at this time in a effort to respond to some other queries this morning.  Perhaps one of our readers will have time to scour the internet for an identification while we are off on what will most likely be a very long day at our place of gainful employment.

Karl provides an identification
Hi Daniel and Tricia:
It looks like a Burnet or Forester moth in the genus Clelea (Zygaenidae: Procridinae), probably C. sapphirina. I couldn’t find confirmation that it is native to Viet Nam but it ranges from India to Hong Kong, so it seems reasonable that its range would include Viet Nam. It could also be another of the several species in the genus but C. sapphirina appears to be a close match. Regards.  Karl

Thanks Karl,
BugGuide refers to the family Zygaenidae as the Leaf Skeletonizer Moths.

Thank you very much for responding, and it will be interesting to see if the post produces anything. I hadn’t realised quite how many wonderful and fantastic bugs there were out there till I started seriously trying to identify what we’d seen –  if I was a bit younger I might have been inspired to be an etymologist!
Thanks anyway,
Tricia

Hi again Tricia,
An etymologist is a person who studies word and their origins.  A person who studies insects is an entomologist.  We personally love the similarity in the pronunciation of these two fields and Daniel called the first chapter in his book, The Curious World of Bugs, “Entomology and Etymology:  What’s in a Name?”

Letter 15 – Western Grape Leaf Skeletonizer

 

what is this??
Hello,
I love your site! It helped me identify a pseudoscorpion that I found in my bedroom the other day. It was very creepy until I figured out what it was. Then I was very relieved and fascinated 🙂 I am doing an ecology project for my Biology class and I need to identify this bug. I have no idea what it is and I was hoping you might. I found it in some bushes near the beach in LaPorte, Texas. It was about an inch long or so. Thanks so much,
Kristine

Hi Kristine,
This looks to us like a Western Grape Leaf Skeletonizer, Harrisina brillians. You will find considerable more information on the similar, orange collared Grape Leaf Skeletonizer, Harrisina americana.

Letter 16 – Western Grape Leaf Skeletonizer

 

iridescent blue flying bug
Thu, Apr 9, 2009 at 9:38 PM
I found three of these iridescent blue bugs in my back yard. Two were mating and the other had fallen in a bowl of water. They are iredescent blue with the exception of their neck which is red. For size comparison, it is on my finger in the first image. At first I thought they were wasps, but there was no visible stinger and I didn’t get stung when it landed on my finger.
Adriana
Phoenix, Arizona

Western Grape Leaf Skeletonizer
Western Grape Leaf Skeletonizer

Dear Adriana,
We are sad you didn’t provide a photo of the mating pair of Western Grape Leaf Skeletonizer moths for our Bug Love page. The Western Grape Leaf Skeletonizer, Harrisina metallica, has a species name that refers to the iridescence you describe. This species has brightly colored caterpillars that can defoliate grape vines if present in sufficient quantities. BugGuide refers to this moth by the compound word common name Western Grapeleaf Skeletonizer. Though they are not Wasp Moths, the species does mimic certain wasps, hence your early confusion.

Daniel,
I’m sorry I didn’t get the picture of them mating for your site. This all
explains why they were in my yard AND what those very pretty, very damaging
caterpillars turn into after they are done devouring my grape vines. I
usually pick them off of the vines each year.
I really appreciate you taking the time to answer my question and hope you
enjoy the pictures I did provide.
Adriana

Thanks for the followup confirmation Adriana,
We did enjoy your photos, and your letter and one of the images was posted to our site yesterday.

Update: Mon, Apr 13, 2009 at 7:14 PM
Here’s your wish come true.
Adriana

Grape Leaf Skeletonizers Mating
Grape Leaf Skeletonizers Mating

Thanks Adriana,
Our internet connectivity was down, so we were unable to post yesterday.

Grape Leaf Skeletonizers Mating

Letter 17 – Western Grape Leaf Skeletonizer

 

Subject: moth? ant?
Location: Tucson, Arizona
March 31, 2017 8:55 pm
I don’t really know what to say here. I’ve never seen an insect like this. It’s completely black, and about the size of a nickel.
At first glance, I thought it was a moth, but it has aggressive looking wings that I relate more closely to a wasp or an ant.
I’m sorry the picture isn’t great. I’m actually pretty terrified of bugs.
Signature: phobic, yet fascinated

Western Grape Leaf Skeletonizer

Dear Phobic, yet fascinated,
Do you have any grape vines nearby?  This appears to be a Western Grape Leaf Skeletonizer,
Harrisina metallica, and you can compare your image to this BugGuide image.  According to BugGuide:  “Larvae are a severe pest in some California vineyards.”  The Western Grape Leaf Skeletonizer is a moth, but it probably derives some protection against predators because of its resemblance to stinging wasps.

Letter 18 – Western Grape Leaf Skeletonizer Caterpillar

 

Subject:  Caterpillar
Geographic location of the bug:  south, CA
Date: 10/02/2017
Time: 09:12 PM EDT
Hi, my name is sarah saxton. I was hoping you can help me identifily this caterpillar. It’s yellow and it has to bule or purple lines near each end. Thankyou,
How you want your letter signed:  you pick

Western Grape Leaf Skeletonizer Caterpillar

Dear Sarah,
Was this Caterpillar found on or near grape vines?  It is a Western Grape Leaf Skeletonizer Caterpillar and you can verify our identification on BugGuide.

Letter 19 – Western Grapeleaf Skeletonizer

 

Grape Leaf Skeletonizer???
Greetings from Palmdale, California! Located in the blazing Mojave Desert. These moths started appearing in our backyard just after it started getting warm out. I like them very much, but I just wanted to double-check my identification before I post the picture up on my website. Yes, we do have grape plants in our backyard, and a Vineyard not far from us (I know, in the Desert of all places!) Am I right?? Thanks so much!
Abbey

Hi Abbey,
You are correct but for one small detail. This is a Western Grapeleaf Skeletonizer, Harrisina metallica, not the Grapeleaf Skeletonizer, Harrisina americana, which is found in the east.

Letter 20 – Western GrapeLeaf Skeletonizer

 

Subject: It’s black with red on its neck
Location: AZ Glendale
April 30, 2017 2:10 pm
I found this outside when searching for my forensic project finding bugs. Anyway I caught it and would like to keep it alive so I don’t kill it before letting it go back t I have no idea what it is or what it eatsSignature: Quinn

Western GrapeLeaf Skleletonizer

Dear Quinn,
Though the red collar is not evident in your image, it helped further specify the identification of this Western GrapeLeaf Skeletonizer,
Harrisina metallica, a moth with Caterpillars that are an agricultural pest on grape vines.  This BugGuide image illustrates the red collar and according to BugGuide:  “Adult: body and wings black with bluish or greenish tint; collar dull orange or red (except in form ‘brillians’ which has black collar)” and “the all-black ‘brillians’ form was formerly considered a separate species.”

Authors

    by
  • Bugman

    Bugman aka Daniel Marlos has been identifying bugs since 1999. whatsthatbug.com is his passion project and it has helped millions of readers identify the bug that has been bugging them for over two decades. You can reach out to him through our Contact Page.

  • Piyushi Dhir

    Piyushi is a nature lover, blogger and traveler at heart. She lives in beautiful Canada with her family. Piyushi is an animal lover and loves to write about all creatures.

56 thoughts on “Grape Leaf Skeletonizer: All You Need to Know for a Healthy Vineyard”

  1. 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

    Reply
  2. 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!

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  3. 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.

    Reply
    • 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.

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    • Thanks David,
      We appreciate this and all your other comments. It might take us some time to provide links to all your identifications.

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  4. 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.

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  5. 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.

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    • Kitchens are not the normal habitat for the Western Grape Leaf Skeletonizer, however, California is within the range of the species.

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    • 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.

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  6. 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???????

    Reply
    • 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.”

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  7. 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?

    Reply
    • We do not provide extermination advice. Perhaps one of our readers will have experience and they can provide the information.

      Reply
  8. 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.

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  9. 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.

    Reply
  10. 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

    Reply
  11. 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

    Reply
  12. 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.

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  13. 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.

    Reply
  14. 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.

    Reply
  15. 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

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  16. 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!

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  17. 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.

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  18. 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?

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    • To the best of our knowledge, they are not poisonous. The caterpillars have hairs which the ducks might find unpalatable.

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    • 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??

      Reply
  19. 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.

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  20. 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.

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  21. 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…).

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  22. 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.

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  23. 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.

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  24. 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.

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  25. 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?

    Reply

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