Elm Leaf Beetle: All You Need to Know for Healthy Trees

The elm

Elm Leaf Beetle Overview

Identification

The Elm Leaf Beetle (Xanthogaleruca luteola) is a small insect, with a yellow to greenish color. They are known for feeding on elm tree leaves, causing significant damage.

Key features:

• Size: approximately 1/4 inch long
• Color: yellow to greenish
• Shape: Oval

Lifecycle

The lifecycle of the Elm Leaf Beetle consists of four stages: eggs, larvae, pupae, and adults. Here’s a brief overview of each stage:

1. Eggs: Females lay eggs in clusters on the underside of elm tree leaves.
2. Larvae: The green to yellow worm-like larvae grow up to 1/2 inch long and feed on the leaves’ underside.
3. Pupae: Larvae move to the tree base in large numbers to pupate.
4. Adults: Adult beetles emerge from pupae and continue feeding on elm tree leaves until it’s time to reproduce.

There are usually two complete generations of Elm Leaf Beetles per year. Adults overwinter in protected areas such as under bark, cracks, crevices, or inside buildings.

Elm tree species affected:

• Siberian elm
• Hybrid elms
• American elm (seldom)

Some elm trees, such as Chinese elm and lacebark elm, are less likely to suffer significant damages from Elm Leaf Beetles.

Signs of Infestation

Damage to Leaves

Elm leaf beetles attack elm trees, causing significant damage to their leaves. The larvae feed on the leaves, leading to a pattern of injury known as skeletonizing. Damaged leaves typically have a lacy appearance and may eventually turn brown.

Holes and Skeletonizing

Elm leaf beetles and their larvae create small holes in newly developing leaves, while avoiding larger leaf veins. This feeding behavior results in a characteristic skeletonized pattern on the leaves. Examples of damage include:

• Tiny holes throughout the surface of the leaves
• Leaves appearing thin and lacy
• Brown and wilted leaves due to extensive damage

Visible Life Stages

Elm leaf beetles have different life stages visible on the elm trees they infest:

• Eggs: Female beetles lay clusters of 5 to 25 eggs on the underside of leaves.
• Larvae: The green to yellow worm-like larvae have a black head and two black stripes along their back, and can grow up to 1/2 inch long ¹(https://www.uky.edu/Ag/Entomology/treepestguide/elm.html).
• Adults: Adult beetles are typically seen chewing small holes in newly developing leaves.

Monitoring and managing elm leaf beetles can help protect elm trees from severe damage and ensure their continued health and longevity.

Prevention and Control Methods

Cultural Practices

• Sanitation: Regularly remove fallen leaves and debris. This helps eliminate elm leaf beetles’ overwintering and pupal habitat.
• Pruning: Prune elm tree branches to promote better air circulation, reducing the attractiveness to beetles.
• Mulching: Apply organic mulch around the base of the tree to maintain soil moisture and improve tree health.

Chemical Control

Effective insecticides for elm leaf beetle management include:

• Spinosad: An organic pesticide derived from soil bacteria, useful for control of elm leaf beetles in both their larval and adult stages.
• Bt (Bacillus thuringiensis): A soil-dwelling bacterium that is toxic to beetle larvae. It should be applied in spring when larvae are actively feeding.

Pros:

• Helps reduce infestation more effectively than using cultural practices alone
• Targeted treatment can minimize impact on non-target organisms

Cons:

• Inadequate application might lead to insecticide resistance
• Potential negative impact on natural enemies (parasitic wasps)

Comparison table: Spinosad vs. Bt

Biological Control

• Parasitic wasps: Encourage the presence of natural enemies like parasitic wasps by providing habitat for them and avoiding broad-spectrum pesticide use.
• Integrated Pest Management (IPM): Implement IPM programs combining cultural, chemical, and biological tactics to keep elm leaf beetle populations below damaging levels.

Example: In a garden with diverse plantings, parasitic wasps are more likely to find and attack elm leaf beetle larvae, reducing the need for chemical intervention.

Impact on Elm Trees

Types of Elm Trees Affected

Elm leaf beetles (Xanthogaleruca luteola) primarily target elm trees, causing significant damage to their leaves. Varieties such as Siberian and European elms are more prone to damage, while others, like cedar elm, lacebark elm, American elm, and winged elm, experience less evident harm².

• Siberian elm: highly susceptible
• European elm: highly susceptible
• Cedar elm: less susceptible
• Lacebark elm: less susceptible
• American elm: less susceptible
• Winged elm: less susceptible

Connection to Dutch Elm Disease

The elm bark beetle, a different species from the elm leaf beetle, plays a crucial role in transmitting Dutch elm disease³. This fungal infection affects several elm species, particularly the American elm¹. Elm bark beetles carry the fungus when feeding on an infected tree, then unknowingly spread it to healthy trees. Dutch elm disease can lead to weakened, dying trees, making it a significant concern across North America.

Comparison of Elm Leaf Beetle and Elm Bark Beetle

Additional Information

Weather Conditions and Infestation

Elm leaf beetles thrive under certain weather conditions. They are most active during the months of May and August, when:

• Temperatures are warmer
• Elm trees are producing new leaves

Elm leaf beetles can cause significant damage to elm trees, making leaves turn brown and affecting their ability to photosynthesize. To manage infestations, various techniques can be employed:

• Systemic insecticides: Applied as soil injections or trunk injections
• Trunk banding: Coating the trunk with a sticky substance to trap beetles

Controlling elm leaf beetle populations outside the tree is also important, as they can often find shelter in:

• Cracks in buildings’ exteriors
• Woodpiles
• Foundations of structures

Keeping these areas clean and free from debris can help mitigate infestations.

Invasive Species of Elm Leaf Beetle

The elm leaf beetle, Xanthogaleruca luteola, is an invasive species originating from Europe. Its larvae have distinctive physical characteristics:

• Greenish-yellow color
• Black stripes along the back
• Black head

These beetles feed on a variety of elm species, particularly Siberian and hybrid elms. However, some elm species, such as the true Chinese elm and the American elm, suffer less damage from elm leaf beetle infestations.

Comparing elm leaf beetles to other insects that may infest elm trees, such as earwigs and stink bugs:

In conclusion, understanding the elm leaf beetle’s behavior, preferred weather conditions, and vulnerable elm species can help in managing and preventing infestations, ensuring the health of elm trees.

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 – Leaf Beetles

Milk Weed Beetles, one red one black
Location:  Lexington NC
August 23, 2010 2:51 am
Finally got a decent shot of one of the quick, non-cooperative little fellas. They scare off quite easily.
The one I was shooting originally is the red/orange color one, then I got a bonus and found a black one not too far from this one.
Rick Nelson (SCWIDVICIOUS)

Hi Rick,
We are a bit confused by the email you sent.  These are not Milkweed Beetles, but Leaf Beetles in the family Chrysomelidae.  Perhaps you found them on milkweed, though your letter did not indicate that.  The red and black specimen appears to be the Six Spotted Neolema, Neolema sexpunctata, a species represented on BugGuide where this information is provided regarding the food plant: “This species is associated with Commelinaceae, having been recorded from Commelina spp. and Tradescantia sp.” Those plants are not milkweeds, and the leaf your beetle is photographed upon does not appear to be a milkweed.  Your second Leaf Beetle may be in the genus Oulema based on BugGuide images.

Letter 2 – Leaf Beetle is Kuschelina species

Subject: Black and Red Ohio Beetle
Location: Greater Cleveland Area
December 22, 2013 2:55 pm
I saw this beetle in my backyard today. I don’t think I’ve ever seen one like this. It was about 3/16″.
Signature: Tim

Hi Tim,
Our initial attempt to identify this Leaf Beetle in the family Chrysomelidae to the species level did not prove successful.  We will continue to research this matter.

Thank you Daniel!

Update:  February 4, 2015
Thanks to an update from Charlie indicating this is a species of Kuschelina, we were able to locate several similar looking species on BugGuide, including Kuschelina gibbitarsa, Kuschelina scripticollis and Kuschelina vians.

Letter 3 – Leaf Beetle: Calligrapha species

Subject: Type of Ladybug?
Location: Hardwick, VT
December 23, 2013 10:41 am
I was doing some work in a cemetery and saw this unusual bug on a gravestone.
I’ve always been intrigued by bugs since I was a child so I decided to take a photo of it.
The cemetery is located in Hardwick, VT and the photo was taken this fall.
Signature: Erick

Hi Erick,
This is a Leaf Beetle in the genus Calligrapha.  According to BugGuide, there are at least 38 species in North America, and many are difficult to tell apart.

Letter 4 – Leaf Beetle: Bassareus brunnipes perhaps

small black and yellow beetle
June 1, 2009
small black and yellow beetle
I took this on May 31 near Tampa FL on one of my yard patrols. I would say the body was approximately one cm in size. As southern transplants, we’re trying to figure out what all these strange, new bugs are that didn’t show their face in the midwest. I think it’s a beetle but?? it was in an oak tree that’s showing some damage and we’re trying to figure out whats killing/eating the leaves. It kept circling the leaf to avoid being photographed and the branch wouldn’t hold still so this is as clear as I could get it. Any help is appreciated. Thanks for such a great site.
Linda
Tampa, FL

Hi Linda,
With the speed of our new computer, we are trying to respond to some old mail that arrived when we were quite busy with the end of the semester and a pending trip to visit family.  Your letter was a pleasant surprise.  We have researched your Leaf Beetle in the family Chrysomelidae, and we are confident it is either Bassareus brunnipes or a very close relative.  BugGuide indicates it is widely distributed in the Eastern U.S., but all the submissions are from Florida and Louisiana.  This is a new species for our website.

Letter 5 – Leaf Beetle: Calligrapha serpentina

pretty beetle
This little guy is one of the most beautiful bugs I have ever seen. We found him on the 4th of July and thought he matched quite well with the occasion. He posed for some pictures and then we took him outside and he flew off into the night. Any idea what kind of beetle it is? Thanks,
Suzanne

Hi Suzanne,
This is a Leaf Beetle in the genus Calligrapha. We believe it to be Calligrapha serpentina based on a BugGuide image.

Letter 6 – Leaf Beetle in genus Calligrapha

Subject: What’s this little fellow?
Location: Eldorado Canyon State park, CO
May 12, 2016 3:49 pm
Hi! My boyfriend and I went for a hike in Eldorado Canyon State park, CO and saw this little cutie! I’ve searched all over the Internet with searches like “fancy ladybug”, “White beetle with violin markings”, and pretty much anything I could think of, but never saw a single one of these! I hope you can help me out!
Signature: Amber

Dear Amber,
Your Leaf Beetle is in the genus Calligrapha but we are not sure of the species.

Letter 7 – Leaf Beetle from the UK

Subject: Googling “olive green beetle” only brings up car pictures….
Location: Milton Keynes, UK
July 25, 2015 3:21 pm
Dear Sir
My friends found this beetle in their house today (25/07/15). They can’t find an exact match in any book…could you help satisfy our curiousity?
Signature: J

Dear J.,
We found a pretty close match to your Leaf Beetle online, but we are not certain if the black thoracic region on your individual is accurate, or a result of the lighting, because all the images of Lochmaea capreae that we found have lighter coloration, including the ones on Diptera Info and on Insects of Scotland where the thorax is described as:  “a slightly yellowish pronotum with three uneven black markings on it.”  So, we are not certain if we have correctly identified your beetle to the species level, but we are confident it is a Leaf Beetle in the family Chrysomelidae.

Letter 8 – Leaf Beetle: genus Calligrapha

Yellow/white w/ black spots, red underwings, beetle
June 10, 2010
Hiking in Chimney Rock park, NC mountains, Hickory Grove Falls hick. Beetle on rock. smallish, more rounded like a ladybird than flattish like a regular beetle. Underwings were red (surprising).
JenG
Chimney Rock park, NC

Hi Jen,
This is a Leaf Beetle in the genus Calligrapha, but as you can see from the number of different yet similar looking species posted to BugGuide, we are unable to provide and exact identification.

Letter 9 – Leaf Beetle Larva

Subject: What’s That Bug?
Location: Lakewood, Ohio
July 25, 2014 10:31 am
We saw this bug at a family picnics at the city park. I’ve been in Cleveland Ohio for 40 years and have never encountered this bug. Looks half caterpillar half insect and very alien.
Signature: Matt S.

Dear Matt,
This is the larva of a Leaf Beetle in the family Chrysomelidae, and knowing the food plant would tremendously help in narrowing down the possibilities.  It is very similar in structure to a Potato Beetle Larva, which causes us to believe it is closely related, and the best we can do right now is to narrow it down to the larva of a Leaf Beetle in the tribe Doryphorina.  You can compare your image to this image on BugGuide.

Letter 10 – Leaf Beetle Larva

Subject:  Unknown larva
Geographic location of the bug:  Virginia Beach,Virginia
Date: 05/04/2019
Time: 09:28 PM EDT
Your letter to the bugman:  Looking for id possibly a sawfly larva
How you want your letter signed:  Maurice Cullen

Dear Maurice,
One of the easiest ways to identify a plant feeding insect is to know the plant upon which it is feeding.  This is actually a Leaf Beetle larva, and we have found a matching image on BugGuide for the genus Trirhabda.  Of the genus, BugGuide notes:  “26 spp. in our area” and “Host plants are in the families Asteraceae and Hydrophyllaceae. Larvae and adults usually feed on leaves and flowers of a single plant species or genus: one group of species feeds on goldenrod (Solidago); another group on wormwood (Artemisia); another on Yerba Santa (Eriodictyon); etc.”

Letter 11 – Leaf Beetle Larva from Australia

Subject: whats that bug
Location: brisdane moggil
December 18, 2014 3:28 pm
have not been able to identify these insects I took these photos myself please help.
Signature: cheers dylan

Dear Dylan,
We received your submission with three unrelated insects attached to a single, very brief identification request.  Before we could even begin, we needed to research the location of “brisdane moggil” which we quickly learned was a spelling error of Brisbane Moggil, an area in Queensland Australia.  We try to the best of our ability to classify postings correctly on our site and information on the sighting is often very helpful.  With that stated, one of your images is of a Leaf Beetle Larva.  If you want any additional identifications, please submit a single individual, but you may attach as many as three images of that individual as sometimes multiple views assist in our identification process.  Please include any relevant anecdotal information regarding the sighting.

Letter 12 – Leaf Beetle Larvae

What is this?
Location: Anchorage, Alaska
September 4, 2011 7:31 pm
I saw these bugs eating an alder bush in my yard up here in Anchorage Alaska. I am wondering what they are and if I need to do anything about them. They are all over the alder bush.
We noticed that when they are touched the white spots on them pop out. I can’t find anything about them online.
Signature: Erica

Hi Erica,
These are Leaf Beetle Larvae, and we believe we found a good match on BugGuide that is identified as Chrysomela aeneicollis, and the photo is from Alaska.  We would also admit that we are not certain of the species, since larvae are often difficult to identify with certainty, but we are relatively confident that we have the genus Chrysomela correct.  Here is another similar looking unidentified larva from the genus Chrysomela, also from BugGuide.  If you read the comments on this posting on BugGuide, you will see that the larvae are capable of emitting drops of odorous liquid from the white tubercles, which supports what you have written.  Our one reservation is that from what we have read, beetles in the genus Chrysomela feed upon willow and poplar, and we haven’t found any indication that they feed upon Alder.

Letter 13 – Leaf Beetle Larvae

Subject: friend or foe?
Location: bridge city, texas
September 16, 2014 3:54 pm
My friend found this on her morning glory. We aren’t sure if its a bug, larvae or egg. We have researched and although we found a few things that looked similar, we haven’t found an exact match or anyone who could help. You’re our last resort! Please help!
Signature: thank you! Crystal

Dear Crystal,
These are Leaf Beetle Larvae in the family Chrysomelidae, and we strongly suspect that they are the larvae of Tortoise Beetles.  Several species of Tortoise Beetles including the Golden Tortoise Beetle have larvae that feed on morning glories, but your larvae look different, though similar, to the images we are able to locate on BugGuide.  Fecal matter that is carried over the back of the larva is a characteristic of many Tortoise Beetles, and it is evident in your image.  Many Tortoise Beetles are very host specific, so if you don’t mind that your morning glory leaves are being eaten, at least you don’t need to worry about the larvae spreading to other plants.

Letter 14 – Leaf Beetle Larvae and Mantis feeding on Tree Frog

Larvae of what?
Hi Mr. Bug Man, I came across these critters eating away at this tree by the hundreds of thousands. The Angeles Crest forest floor was strewn with thousands of leaves with the same lace-like damage done to them. This photo is of a leaf still on the tree with some of the culprits on board. Any idea which species this larvae belong to? Best regards,
H. Markarian

PS I’ve also attached a beautiful photo of a mantis gorging on a frog.

Dear H,
We wish you had included additional information on both of your images. The larvae look like Leaf Beetle Larvae in the family Chrysomelidae. We did a google search for California and came up with the Willow Leaf Beetle, Chrysomela aeneicollis. That is a guess. You did not provide size information which would have been helpful. We will see if Eric Eaton can correctly identify these larvae. Here is Eric’s input: “I am pretty certain you are correct, at least to family level. Without knowing the host tree, genus and species identification probably can’t be accomplished. Eric”. Also, did you shoot the Mantis photo with the Tree Frog? Was it shot in the wild or in captivity? Where was the photo taken if in the wild? So many unanswered questions on a beautiful image.

Thanks for such a prompt reply to my last email. Regarding the larvae, they were about as long as a fingernail. It wasn’t a willow tree they were munching on, but i looked up willow leaf beetle online and the larvae definitely resembled the ones I saw in the wild. I came across the larvae on a trail in the Angeles National Forest in Southern California. As regards the mantis eating the tree frog, both were caught from the wild separately and placed in the same container temporarily. We had no idea the mantis would be able to catch, hold and eat an animal much stronger and heavier than it was. I took the photo while the critters were in captivity. Thanks for your time and feedback. You have a fascinating website. Best Regards,
H. Markarian

Letter 15 – Leaf Beetle: Red Megacerus

Subject: Beetle with False Eyes?
Location: Ottawa, Ontario
August 22, 2014 7:26 pm
This tiny critter is eating my butterfly bush. But I guess nobody will be eating him because he seems to be flying the jolly roger on his butt. False eyes?
Signature: Joanne

Dear Joanne,
This lovely beetle really threw us for us for a momentary loop, because the body resembles that of a Scarab Beetle, but the antennae are decidedly un-Scarab-like.  We quickly identified this Leaf Beetle in the family Chrysomelidae as Megacerus discoidud thanks to Beetles of Eastern North America, the new book by Arthur V. Evans.  According to BugGuide:  “This handsome species with its quadrate, red elytral maculae can hardly be mistaken for any other eastern American bruchid.”  BugGuide also indicates:  “Adults are commonly found on flowers of many plant species” and “Host plants: Calystegia spp.; Convolvulus arvensis; Ipomoea spp. Flowers of Daucus carota and Hibiscus sp.” 

Thanks for the speedy reply!
Mystery solved…
Joanne Pasieka
Ottawa, ON

Letter 16 – Leaf Beetle we presume

what kind beetle is this?
Location: s indiana
November 21, 2011 7:17 am
Any ideas? thank you
Signature: brian

Dear Brian,
Using BugGuide, we properly identified your beetle as a Larger Elm Leaf Beetle, Monocesta coryli.  Images posted to BugGuide indicate this is a variable species that may have black markings.

Letter 17 – Leaf Beetles

Type of bug eating the leaves of my tree?
Hi,
The attached picture of these little bugs that are eating the leaves of one type of tree I have. They are about the size of your little finger’s nail. They are only attacking this one type of tree I have, not sure what kind of tree it is, but I have Elms and Oaks and they don’t mess with them. This tree is very large, probably about 4 foot in diameter. I’ve been constantly spraying the trunk up to about 12 feet up and so far are controlling them…but my neighbor has the same kind of tree and they are in it too but he’s too lazy to spray them. I cannot find any evidence of the bugs borrowing out of the bark, I can’t find any holes anywhere, but the bark is very coarse. Any idea what these bugs are or how to better controll them?
Thanks,
Robert Downey

Dear Robert,
We wanted to be sure about the identity of your beetles, so we wrote to Eric Eaton who quickly responded: “Well, if they are from the U.S., then they are leaf beetles in the genus Calligrapha, family Chrysomelidae. All bets are off if they are from outside North America north of Mexico:-) Neat insects.
Eric”

Letter 18 – Leaf Beetles: Mating Striped Cucumber Beetles and Unknown Family Member

Beetle
Can you please tell me what these bugs are? The yellow one was found on our squash plants, and the other in the grass. We live in the Baton Rouge, La. area.
Thanks,
Jeanette Murray

Striped Cucumber Beetles	Unknown Leaf Beetle

Hi Jeanette,
These are both Leaf Beetles in the family Chrysomelidae. The ones mating on the squash plant are Striped Cucumber Beetles, Acalymma vittata. The other beetle is also one of the Leaf Beetles, but we are not sure of the species.

Letter 19 – Leaf Beetles, we believe

Subject:  Small black beetles  with jewel colors of blue and violet
Geographic location of the bug:  Little Belt mountains Montana
Date: 08/20/2018
Time: 11:48 AM EDT
Your letter to the bugman:  I have seen these in the months of June and July on blooming mountain lupines in the Little Belt and the Castle Mountains. I would like to know what kind of beetle these are?
How you want your letter signed:  David C Powers

Dear David,
The image of a solitary beetle on a blossom is definitely a Blister Beetle in the family Meloidae, but we are uncertain of the species.  The other image showing an aggregation of Beetles appears to be a different species.  Can you clarify any information on these two images, especially the group of beetles.  Were they found aggregating as the image depicts?  Here is a BugGuide image of Linsleya sphaericollis that resembles the Blister Beetle in your image of a solitary individual, but again, we cannot verify the species.

Hi, thank you for the quick response.  The aggregation of beetles I thought was the same, as the solitary beetle. But on closer inspection, I see differences in body shape. The plant is not mountain lupine. I realized I had grabbed two images taken at different places. The group is later in the summer.  Each beetle isn’t very big. Maybe 3/8 to 1/2 inch. I am looking at the plant they are eating it isn’t milkweed or dogbane.  Here are more photos. They are part of the group. I isolated out a few of the beetles. They are mostly in focus. The photo was taken in July or August in Montana in the mountains.

Cheers

David

Dear David,
Your newly submitted images appear to be the same beetles that were in your original aggregation image, and we believe they are Leaf Beetles, possibly Flea Beetles from the genus Altica like the ones in this BugGuide image.

Letter 20 – Lily Leaf Beetle

Flat Bark Beetle?
Hi Daniel,
My sons and I have found a few of these critters while finishing up the last minute gardening. I’ve looked for a match in the beetles section, as well as the true bugs section without much progress. It kind of looks like a flat bark beetle, but my specimen has more of a rounded body. Can you tell us what this bug is?
Thanks a lot!
Yvonne, Derek and Jason
Barrie ,
Ontario

Hi again Yvonne, Derek and Jason,
This is one of the Leaf Beetles in the Family Chrysomelidae. Sorry we don’t know the species. We checked with Eric Eaton as well and he agrees with us and has seen this specimen pictured on BugGuide, but can’t recall the species. We did a cursory search of BugGuide and could not immediately locate it.

Ed. Note: (11/07/2005) This just in.
red leaf beetle
Hi
I love your site and visit it on a regular basis looking for the ID of different bugs I find and photograph. I noticed that you had a photo of a red leaf beetle sent in on 10/31/2005 from Yvonne, Derek and Jason from Barrie, Ontario. I am pretty sure it is the lily leaf beetle, Lilioceris lilii. This beetle was first found in Montreal, Canada in the mid 1900’s but has since spread and is known to be in Ontario. Thanks for all the work you must do to make What’s That Bug such a great and useful site. Beth Hoar
Prince Edward Island, Canada

Ed. Note:(11/07/2005) And Yvonne wrote back.
Lily Leaf Beetle
Hi again Daniel, I just looked up the Leaf Beetle you named for me from my recent picture. Would I be right in saying that it’s a Lily Leaf Beetle? I found a website with some pictures and information. http://www.uoguelph.ca/pdc/Factsheets/Insect/LilyLeafBeetle.htm Let me know what you think. Yvonne

Letter 21 – Lily Leaf Beetle

Red Beetle?
Mon, May 11, 2009 at 1:47 AM
Found this on my lily plant leaf. Would like to know about it, especially if it is harmful to my garden and greenhouse plants.
Katie
Leicester, UK

Hi Katie,
This is a Lily Leaf Beetle, Lilioceris lilii.  This beetle is native to Europe and has recently been introduced into parts of North America.  The larvae and adults feed on the leaves of true lilies, and can become so numerous they become a pest.  BugGuide has a nice dialog about the Lily Leaf Beetle, including one person calling them the “scourge of Cambridge” and others recommending using black pepper to control their numbers.

Letter 22 – Lily Leaf Beetle

RED BUG
Location: Peabbody, Massachusetts.
June 15, 2011 8:00 am
This critter appears overnight and usually with allthe kin to start a hostile takeover.
The bug is normally solitary but will share an occassional leaf with another.
These bugs apparently hate direct light because I always find the bug under the leaf.
These bugs can destroy an entire Tiger Lilly in an hour. Then move onto the next plant.
What is it’s name; how do I control this plague?
Signature: Rod

Hi Rod,
The Lily Leaf Beetle, Lilioceris lilii, has been introduced from Europe and it has gained a major foothold in Canada and New England.  As your letter indicates, it feeds on the leaves of domesticated lily plants.  The best way to control them is to get the larvae.  Once they are adults, they are reproducing and they can fly, making them more mobile.  According to BugGuide:  “The larvae are found beneath mounds of dark brown “crud” along the edges of leaves they are eating, literally a protective barrier of their own feces.”  We would recommend that you target the larval stage in your attempts to eradicate the Lily Leaf Beetle from your garden.

Letter 23 – Lily Leaf Beetle

Red beetles
Location: Torrington, CT
June 20, 2011 9:37 am
These little red guys are all over my hostas. Can you tell me what they are? LOVE your site, but what happened to your Facebook page? I loved having neat bugs sent to me every day! Happy bugging!!
Signature: Jennifer

Hi Jennifer,
This is a Lily Leaf Beetle, Lilioceris lilii, a species recently accidentally introduced from Europe.  It is firmly established in Canada and New England.  Until your letter, we did not realize that Hosta is a member of the Lily family.  We will check with our web host regarding your Facebook question, since that is not a matter that our editorial staff controls.

Letter 24 – Lily Leaf Beetle

Subject: Who is this?
Location: Brewster, NY
June 26, 2013 1:06 pm
A horde of these critters attacked my lilies, which I just discovered this morning (June 26). All the leaves were gnawed off, all the buds chewed into. I found zillions of these guys on the stems and buds. Of course they just fly off if I try to get them as I’m removing the dead plants. But they just moved next door to my stella doras, staging on the mum plants between the destroyed lilies and the stella doras.
I can’t find this in any of my bug books. Can you tell what it is? Is there anything much I could do about it? Obviously they love the lily family, but would they likely move on to other plants if these were not available?
Signature: Sister CG

Dear Sister CG,
This is a Lily Leaf Beetle, Lilioceris lilii, and it is an introduced species that has not made friends with gardeners who cultivate lilies.  You can read more about Lily Leaf Beetles on Gardener’s Supply Company.

Ah-HA! Thank you so much for this quick reply. I’m off to research possible treatments for this. We have a fully organic farm here, and the affected lilies are already goners for this year, so I’m thinking vinegar/water/soap to begin with. We’ll see.
Again, thanks so much for the help! (And no, this gardener is not in the mood to make friends with these guys either, pretty as they are.)
Catherine Grace, CHS
Bluestone Farm and Living Arts Center

We hope you are able to find an eco-friendly means of eradicating this invasive, exotic species from your farm.

Letter 25 – Lily Leaf Beetle from Canada

Bright Orange Beetle found on Tiger Lily
April 27, 2010
Hi,
I found a few bright orange beetles, about the size of a shelled sunflower seed outside on the Tiger Lily last July. I’ve looked through some insect books, and haven’t been able to figure out which it is. Any sort of tentative identification would be helpful. Thanks!
Paul Manning
Annapolis Valley, Nova Scotia, Canada

Hi Paul,
Your beetle is a Lily Leaf Beetle, Lilioceris lilii, a species accidentally introduced from Europe that has become established in Canada and the eastern portion of the United States.

Letter 26 – Lily Leaf Beetle: Metamorphosis stages

Red Lilly Beetle
Location:  Naugatuck,CT. USA
July 31, 2010 11:17 am
Hi there love this site, I have been interested in insects since I was little. I have never seen this nasty little red devil until this summer nibbling on my lillies. I looked it up and found it was a Red Lilly beetle. Also that they are a recent invasive species.

I have 3 photos 1 of the eggs, one of the larval stage(very disgusting) and one of the adult. I haven’t seen any pics of them on your site and hoped you could use them? There are quite a few of them in my garden now and my lillies are totally destroyed. I am not that sad the garden is there to attract the bugs.
David K. Howe

Hi David,
Your excellent documentation of multiple phases of the metamorphosis of the invasive Lily Leaf Beetle, Lilioceris lilii, are greatly appreciated.  We have images in our archives of the adults, but your egg and larva images are a first for us.

Letter 27 – Lily Leaf Beetles Mating

Hi Bugman,
Any idea what’s these bugs are please? I felt like a gooseberry interrupting for the photo! Cheers
Steve

Hi Steve,
These are mating Lily Leaf Beetles, Lilioceris lilii. You probably don’t want them to have too many progeny since they can be very destructive by eating the leaves of plants in the lily family. This is an immigrant species, not native to North America.

Letter 28 – Mating Leaf Beetles

what’s eating my greens?
May 22, 2010
It’s a long and slender beetle with a red head, sleek black body with white stripes. A pretty bug, really. Striking and bold. But should I kill them? I assume they’re eating my garden, along with those damned flea beetles. What to do?
Green Gardener
NW Washington DC

Dear Green Gardener,
These are Leaf Beetles in the family Chrysomelidae, and they appear to be mating, not eating.  We believe we have correctly identified your beetles as Calligrapha californica based on images on BugGuide.  BugGuide indicates “Larva feed on beggarticks (Bidens sp.) and possibly other plants” and that “The British Columbia Cranberry Growers Association considers Calligrapha californica beneficial, as it feeds on weeds in their cranberry bogs.“

Letter 29 – Leaf Beetle Larva from Georgia: Trirhabda bacharidis

Metallic rainbow beetle larvae in GA, USA wetland.
Location: Augusta, GA, USA
February 17, 2012 7:04 pm
Hi, I found these larvae in large nests (clumps of dried leaves held together with webs) in a common shrub in an Augusta, GA wetland on February 11, 2012. I don’t know the name of the shrub, but I know it’s very widespread in wetlands in the southeastern USA. At any rate, these nests were very common throughout the shrubs, with several nests per shrub, and each nest seems to contain several larvae in various instars. The largest larvae I saw were ~1 cm long.
Thanks!
Signature: Sarah

Hi Sarah,
WE are posting your photos as unidentified because we haven’t the time to research this at the moment.  Perhaps one of our readers will supply an answer in our absence.  The nest is quite a curiosity.  We wish you could supply the name of the plant.

Comment from
That is the larva of Trirhabda bacharidis (Weber), a leaf beetle which is host specific to salt bush, Baccharis halimifolia. Don’t think it has anything to do with the “nests.”

It is interesting that the species name of the Leaf Beetle is derived from the generic name for the host plant.  We located this Coleopterists Bulletin article entitled “The Host Specificity and Biology of Trirhabda bacharidis“.  BugGuide calls it the Groundselbush Beetle.

Update from Sarah
March 31, 2011
I apologize for my tardy reply, but I believe the mystery is mostly solved.  I took the plant to a botanist and the bug to an entomologist at Georgia Southern University.  The botanist said the plant is Baccharis halimifolia, eastern baccharis.  The entomologist said he thinks the larvaea are Chrysomelid beetles, but he can’t identify them to species unless they’re grown out to adults.