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:

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:

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:

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.

By integrating these prevention and monitoring strategies, grape growers can effectively manage grapeleaf skeletonizer infestations and maintain the health of their vines.

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

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

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.

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

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

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

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

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

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

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

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.

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

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

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

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

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

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

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

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

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

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.”