Cereal Leaf Beetle: All You Need to Know for Healthy Crops

Cereal leaf beetle is an occasional yet potentially severe pest in wheat, oats, barley, rye, and other grasses. This insect species originated from Europe and Asia and quickly spread throughout most of the eastern United States since its first detection in 1962 ¹.

These pests pose a threat to cereal crops, with both adults and larvae causing significant damage. However, there has been success in implementing biological control methods to reduce cereal leaf beetle populations ².

Cereal Leaf Beetle Overview

Origin and Habitat

The cereal leaf beetle, scientifically known as Oulema melanopus, is a pest native to Europe and Asia ¹. They were first detected in the United States in 1962 and have since spread to most wheat-growing areas in the eastern United States ².

Importance as a Pest

Cereal leaf beetles are problematic pests in cereal crops, causing significant damage to crops like wheat, barley, and oats ³. Both larvae and adults can harm the plants, impacting yields and crop quality ⁴.

Pros of the beetle:

Acts as a natural control for certain weed species

Cons of the beetle:

Damages cereal crops
Impacts crop yield and quality

Host Plants

Cereal leaf beetles primarily target cereal crops for feeding, including:

Wheat
Oats
Barley
Rye
Other grasses ⁵

In addition to cereal crops, they may also occasionally feed on other plants such as wild grasses ⁶.

Comparison Table

	Cereal Leaf Beetle
Habitat	Europe and Asia
Introduced to	United States
Target Crops	Cereals and grasses

Life Cycle and Identification

Eggs

Cereal leaf beetles lay eggs individually or in batches
Typically found near the food supply

The female adult lays her eggs in and around the food supply, ranging from 45 to 285 eggs per year. Eggs hatch into larvae within 3 to 10 days, depending on the environmental conditions. source

Larvae

Spiky and slug-like appearance
Feeds primarily on cereal leaves

Cereal leaf beetle larvae can cause significant damage to crops as they feed on the leaves. They have a spiky, slug-like appearance that distinguishes them from other insects. Larvae usually mature into adults within 50 days. source

Pupae

Pupa stage occurs before adulthood
Duration varies depending on the environmental factors

Cereal leaf beetle larvae go through a pupa stage before becoming adults. The duration of this stage varies, depending on the environmental factors, but it’s a crucial phase in their development.

Adults

Oval-shaped bodies with metallic bluish-green coloration
Cause significant damage to cereal crops

Adult cereal leaf beetles have oval-shaped bodies and a metallic bluish-green color, making them easily distinguishable from other beetles. Both adults and larvae can cause significant damage to cereal crops. Biological control methods, such as parasites and predators, have been effective in reducing their populations. source

Damage and Impact on Crops

Affected Plants

Cereal leaf beetles (CLB) primarily target cereal crops, such as:

Wheat
Oats
Barley
Rye
Other small grains

These beetles overwinter and emerge in spring, potentially infesting both winter and spring wheat.

Common Injuries

CLBs, both larvae and adults, cause damage to crops. They typically feed on the upper surface of the leaves, which results in:

Longitudinal, narrow feeding strips
Skeletonization of leaves
Potential defoliation

Impact on Yield

The extent of the damage depends on the severity of the infestation. Significant injury to crops leads to reduced yield, directly affecting farmers’ production. Various factors influence the impact of CLBs on crop yield:

Pros:

Biological control is effective in reducing CLB populations.
Reduced pesticide use with genetically engineered crops.

Cons:

Severe infestations can lead to significant yield loss.
CLBs can spread quickly to new areas, increasing the risk of damage.

The table below compares the potential effects of cereal leaf beetles on wheat and oats:

Crop	Moderate Infestation	Severe Infestation
Wheat	Slight yield decrease	Significant yield loss
Oats	Minimal impact	Major yield reduction

In conclusion, understanding the damage and impact of CLBs on cereal crops is crucial for proper management and yield optimization.

Monitoring and Scouting

Threshold Levels

Managing cereal leaf beetles effectively requires understanding their threshold levels. In general, a treatment is recommended when:

There are 3 or more larvae per tiller in wheat or 1 larva per flag leaf
There is a 20% or higher defoliation rate
Adults are causing significant damage before the boot stage

Scouting Techniques

Scouting for cereal leaf beetles is an essential part of pest management. Some effective scouting techniques include:

Visually inspecting plants for adult beetles, larvae, and signs of feeding damage
Shaking plants over a surface to dislodge and count the insects
Randomly sampling tillers from different areas of the field

When to Monitor

Monitoring cereal leaf beetles should begin in early spring and continue throughout the growing season. Key times to monitor are:

As soon as plants begin to emerge
During the tillering stage
Around the boot stage when larvae are most active and damaging

By understanding the threshold levels, scouting techniques, and the appropriate times to monitor cereal leaf beetles, you can make better pest management decisions in cereal crops, helping to reduce potential yield losses. Remember to keep monitoring throughout the growing season, especially during the key times mentioned, to stay on top of potential issues and take action when necessary.

Integrated Pest Management

Biological Control

Biological control involves using natural enemies to manage cereal leaf beetle populations. One effective example is the parasitic wasp, Tetrastichus julis, which attacks beetle larvae¹. Some benefits of biological control include:

Safe for non-target species
Minimizes chemical pesticide use
Helps maintain ecological balance

Chemical Control

Chemical control is another option, using targeted pesticides to manage the beetles. For example, using insecticides like pyrethroids effectively reduces cereal leaf beetle populations². Some pros and cons of chemical control are:

Pros:

Fast-acting
Can be effective in high infestations

Cons:

Potential harm to beneficial insects
Possible development of pesticide resistance

Cultural Practices

Cultural practices should be employed to create a less favorable environment for the cereal leaf beetle. Some methods are:

Crop rotation³
Timely planting and harvesting
Regular field scouting and monitoring

Method	Benefits	Drawbacks
Biological Control	Non-chemical, specific	May take time for results
Chemical Control	Fast, can handle large infestations	Non-target impact, possible resistance
Cultural Practices	Can prevent problems	Requires consistent management

Typical Control Methods

Insecticides

Insecticides are often used to control cereal leaf beetles. Examples include:

Pyrethroids: A synthetic compound effective in controlling cereal leaf beetles, but may have negative impacts on beneficial insects. Penn State Extension suggests pyrethroids as one of the insecticides for controlling cereal leaf beetles.

Pros and Cons of Insecticides

Pros

Effective in controlling cereal leaf beetles
Can provide quick results

Cons

Can be harmful to non-target organisms
Resistance to insecticides may develop in pests

Spraying Techniques

Applying insecticides using appropriate spraying techniques is essential for effective pest control. Key aspects of spraying include:

Timing: Spray when you observe larval feeding and before damage becomes severe.
Coverage: Ensure thorough coverage of the crop to reach all pests.

Alternative Treatments

There are non-chemical options for controlling cereal leaf beetles, such as:

Cultural control: Crop rotation breaks the life cycle of pests, reducing populations.
Physical control: Handpicking beetles can be an important way of managing infestations in smaller gardens. UC IPM suggests using a bucket filled with soapy water to collect the beetles.
Biological control: Parasitic wasps, predators, and pathogens can play a role in controlling cereal leaf beetles.

Comparison of Control Methods

Control Method	Effectiveness	Eco-friendliness	Cost	Speed of action
Insecticides	High	Low	Varying	Fast
Spraying Techniques	High	Medium	Varying	Fast
Alternative Treatments	Medium	High	Low	Slow

Regional Prevalence

Midwest

Cereal leaf beetles have spread to various regions across the United States, including the Midwest. While their impact in this area can be significant, effective biological control methods have helped to reduce their populations ¹(https://smallgrains.wsu.edu/insect-resources/pest-insects/cereal-leaf-beetle/).

East Coast

The East Coast, since the first detection of cereal leaf beetles in the United States in 1962, has experienced their presence in most wheat-growing areas ²(https://extension.psu.edu/cereal-leaf-beetle).

North Carolina

In North Carolina, cereal leaf beetles have caused damage to wheat crops.
Biological controls, such as parasites and predators, have assisted in lowering their populations ³(https://agresearch.montana.edu/wtarc/producerinfo/entomology-insect-ecology/CerealLeafBeetle/USUFactSheet.pdf).

Virginia

Cereal leaf beetles are prevalent in Virginia as well.
The presence of these beetles in grain can restrict exporting to other countries and states ⁴(https://agresearch.montana.edu/wtarc/producerinfo/entomology-insect-ecology/CerealLeafBeetle/USUFactSheet.pdf).

Example:

Cereal leaf beetles can damage wheat plants by feeding on their leaves.
They can reduce the crop yield due to the damage they cause.

Comparison Table:

Region	Prevalence	Control Methods
Midwest	Medium	Biological control methods
East Coast	High	Biological control methods
North Carolina	Medium	Parasites, predators
Virginia	Medium	Regulatory control

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 – Frog Legged Leaf Beetle from Malaysia

Green Metal Beetle
Location: Penang, Malaysia
March 27, 2011 11:24 pm
Hi Bugman!
I’ve developed an interesting hobby which is macrography but most of the time I’ve failed to identify the bugs within the photo because didn’t have much information on them. I’ve hope that I could learn more of this lovely insects and hopefully share my photos for all to enjoy 🙂
Signature: mysticz

flea_beetle_mysticz — Frog Legged Leaf Beetle

Dear mysticz,
This is some species of Flea Beetle in the tribe Alticini. Flea Beetles are in the Leaf Beetle family Chrysomelidae and the feed upon the leaves of plants. Many Leaf Beetles are very host specific and many are considered agricultural pests. We are going to try to research the exact species of Flea Beetle in your photo. We did find a photo of your beetle on TrekNature, and it was photographed in Malaysia, but the species is not identified, and though it is identified as a Leaf Beetle, it is classified in a different subfamily. We believe our Tribe identification to be correct, though we might be wrong. TrekNature indicates: “in reality I think the local call it ‘Kumbang Hijau’ of equivalent to green beetle.” We also found a photo of a similar beetle identified as a Frog Legged Beetle, Sagra buqueti, on the pharmasiana website, but that posting is riddled with incorrect information, beginning with the classification in the order Lepidoptera (moths and butterflies) rather than Coleoptera (beetles), however we are going to pursue that information to see if we can get verification from a credible website. God of Insects shows a Malaysian Frog Legged Beetle pair, Sagra buqueti, and the taxonomy is family Chrysomelidae. The contrary information is on ZipCode Zoo where Sagra buqueti is identified as a Sphinx Moth. The metallic coloration on the beetle images of Sagra buqueti differs from the green of your specimen, but they do look similar and we believe they may be closely related. Scrolling down the I Love Flower Beetles Blog will show a posting dated October 12, 2010 that profiles the Frog Beetles and a video is included. We believe we hit upon the correct ID, again on TrekNature, where a beetle identified as Sagra femorata looks identical to your beetle, down to the color. There is a photo of a dead specimen on the Southeast Asian Beetles page of Beetle Diversity. God of Insects calls Sagra femorata a Frog Legged Beetle and indicates it comes in variable color forms, including blue, green, red and magenta. We end our search satisfied that this is a Frog Legged Leaf Beetle, Sagra femorata by linking to one final image on TrekNature.

sagra_femorata_malaysia_mysticz — Frog Legged Leaf Beetle

Mr Bugman,
Thank you so much for the identification, love and will continue to support your site.
b.rgds
mysticz

Letter 2 – Leaf Beetle

Waiting for identification
August 4, 2011 6:24 pm
Hi
I submitted a photo mid last month hoping you could help me. I fully acknowledge that you state you are a small team and don’t manage to respond to everyone. My question is how long should a person wait before they assume you weren’t able to help them? E.g. If I haven’t heard or seen it on your site by now should I assume you couldn’t help me?
Thanks in advance.
Kristin
Signature: Kristin hoskin

Hi Kristin,
As you indicated, we cannot answer all of our mail. Please resubmit your image and questions to this email and we will try to respond. Don’t forget to include your location since you will not be using the form this time.

Original information from early July
Hi
thank you. Sorry for the delay in reply. I’ve been sick and was not checking emails. Here is my submission response email.
The location of the photo was Bosque, Texas. My home location is Christchurch, New Zealand.
Your submitted question:
I’ve been visiting Texas and chasing bugs because they move slower than the birds there and I have a better chance of getting a good shot. I’m having trouble finding the name of this one though. Can you help? The photo file name is the date and time the photo was taken in Zulu not Central US Daylight Savings Time if that helps with identification.

Ed. Note: To be continued …

August 9, 2011
Since Mom is visiting the editorial staff, we are trying to limit the time we spend online. This appeared to us to be a Leaf Beetle, but we did not recognize it and Leaf Beetles can be quite difficult to identify properly, so we wrote to Eric Eaton to get his opinion. Here is his response.

Eric Eaton’s opinion
Daniel:
Not positive, but I’m thinking it is a leaf beetle, Anomoea nitidicollis:
http://bugguide.net/node/view/218151
Larvae are casebearers.
Eric

Thank you. I’ll keep surfing based on that to find out more about them.
I must say – you do a great job. I spent several hours on bug photos today and was pleased at the end of my efforts to have identified five of them. How you do so many amazes me!
Regards
Kristin

Letter 3 – Leaf Beetle

tomato leaf eating bug
I hate this thing! Tons of them are eating my tomato plants!
robert

Hi Robert,
The closest I can get for you is it is one of the Chrysomelidae, or Leaf Beetles. It looks to be a close relative of the Cucumber Beetles.

Letter 4 – Frog Legged Leaf Beetle from Cambodia

Green/Blue Beetle
Location: Phnom Penh, Cambodia
August 13, 2011 9:24 am
Hi,
hoping you can help identify this little beauty.
Found on a rose bush in Phnom Penh, Cambodia – mid afternoon, rainy season.
Signature: C

frog_legged_leaf_beetle_cambodia — Frog Legged Leaf Beetle

Dear C,
If you are interested in more than a name, you can find all the research we have done to identify a previous submission of the Frog Legged Leaf Beetle, Sagra femorata, by reading our archives.

Letter 5 – Globe Mallow Leaf Beetle

Subject: I call them Sith Lady Bugs
Geographic location of the bug: Sierra Vista, Arizona, USA
Date: 09/12/2017
Time: 08:46 PM EDT
9/9/2017 San Pedro Riperian. Don’t they look like Darth Sith? Just wanted to share photos.
How you want your letter signed: ptosis

Dear ptosis,
We are quite confident we have identified the orange beetles as Globe Mallow Leaf Beetles, Calligrapha serpentina, based on this BugGuide image, and based on other BugGuide images, it appears this beetle has variable coloration. According to BugGuide: “Found on Mallows, pattern typical for genus, but details of pattern are fairly constant. Coloring varies from red to a striking light green (the green is an almost translucent metallic sheen over a yellowish to orange base). Differently colored individuals can often be found at one time in one population, but on average most individuals tend to be mostly the same color at one place and time. One generation is commonly a different color than the next.” We are also confident that the light beetle in your third image is a member of the same genus, but most likely a different species.

Thank you so much! wow. I really thought they were a Sith Maul version of Ladybugs. Thank you so much!

Letter 6 – Groundselbush Beetle Larva

Subject: Rainbow larva
Location: Southwest Louisiana
April 18, 2014 6:35 pm
Located these beauties munching on a small tree a few hundred yards from the coast here in southwestern Louisiana. Relatively small at less than a 1/2 inch. Not very active and pretty much play dead when disturbed. Internet search turned up nothing. Any ideas?
Thank you!!
Signature: Karla

Hi Karla,
We were just going to write back that this is the larva of a Leaf Beetle in the family Chrysomelidae, but we decided to continue searching for its species identity. After a bit of searching, we found a matching image of a Groundselbush Beetle Larva, Trirhabda bacharidis, on BugGuide, and we are confident that it is the correct identification for your individual. According to BugGuide: “larvae and adults feed exclusively on leaves of Baccharis (Asteraceae) and it has been “Introduced into Australia and Asia to control Baccharis.” We thought this was a new species for our site, but we were wrong.

Letter 7 – Japanese Poplar Leaf Beetle from Japan

Subject: Head Like a Parrot with a Black Jacket
Location: Japan, Tokyo
October 8, 2012 12:12 am
Hi, I’m living in Tokyo and discovered this cheeky character feasting on my flowers yesterday 10-06-2012 I’ve searched all over the web and in a few books but can’t seem to place him.
Many thanks!
Signature: Harry

japanese_poplar_leaf_beetle_harry — Japanese Poplar Leaf Beetle

Hi Harry,
We love your subject line. We found your Leaf Beetle on FlickR where it is identified as a Japanese Poplar Leaf Beetle, Aulacophora nigripennis. We then verified that identification on Natural Japan where it states: ” This species is very common. It eats the leaves of wild plants such as gourds (uri), but also attacks commercial crops (e.g. soybeans and carnations).” The Japanese name is given as “kuro-uri-hamushi.”

Letter 8 – Labidomera clivicollis, a Leaf Beetle

bug?
hi –
great website, hope you can identify this bug for me. it was on a blade of grass in the lawn near binghamton, ny. it’s about 2 or 3 times as big as a typical ladybug, is it a pest or helpful?
thanks,
cory

Hi Cory,
We checked with Eric Eaton to see if he agreed that this is Labidomera clivicollis, one of the Leaf Beetles in the Family Chrysomelidae, and he agreed. These beetles are usually found on swamp milkweed, but sometimes they attack cultivated members of the genus Asclepias, ornamental plants in the milkweed family. They hibernate in the wooly leaves of mullein according to Comstock.

Letter 9 – Lantana Leafminer Beetle from Australia

Subject: Smiley-Faced Bug
Location: Sans Souci, Sydney Australia
January 24, 2015 9:00 am
Hi, I was hoping you might be able to identify this smiley faced bug from Nsw, Australia.
Regards
David Miller
Signature: David Miller

Dear David,
This sure looks to us like a Leafminer Beetle in the family Chrysomelidae, probably a Lantana Leafminer Beetle, Octotoma scabripennis, which we found pictured on the Brisbane Insect Website where it states: “Lantana Leafminer Beetles are easily found on Lantana. Their larvae mine in the middle layers of leaves and pupate there. The adult beetles feed on the leaf surface. “ We also learned: “Lantana Leafminer Beetles are introduced to Australia as a biological control to the weed Lantana Lantana camara. The beetle’s feeding activities reduce plant vigour and suppress flowering.” The Department of Agriculture, Fisheries and Forestry Biosecurity Queensland site has an excellent Fact Sheet on the Lantana Leafminer Beetle where we learned: ” Octotoma scabripennis occurs naturally from Mexico to Nicaragua. Cultures of Octotoma scabripennis originated from Mexico. The insect was first released in Australia in 1966.” The Lantana Leafminer Beetle is also pictured on the American Insects site.

Letter 10 – Larger Elm Leaf Beetle

unknown beetle
Hello Bugman.
I have just discovered your site, and I love it! I’m a park ranger at Shenandoah National Park. We have a beetle that none of us have been able to identify, and I’m turning to you for help. I am attaching a photo of this yellow beetle that has green and yellow banded elytra. It is a fairly docile creature, and has sat and groomed itself while sitting on my arm (it cleans its antennae in much the same way a cat cleans its ears….). I have seen it at the highest peaks (just over 4000 feet elevation), and pretty much everywhere else within the park. I have not seen it actually eating anything, and haven’t been able to associate it with any particular plant. My wild guess is that is a Chrysomelid beetle, but that’s as far as I could get. Can you help me, please? This beetle is so abundant all of a sudden, and we get so many questions from visitors. My fellow rangers are always on my case because even "Ranger Bug" can’t figure this one out…
Thanks!
Lucia Napolitano
Park Ranger, Interpretation
Shenandoah National Park
3655 US Highway 211 East
Luray, VA

Dear Ranger Bug,
Quite like you, we knew this was a Chrysomelid Beetle, but were unsure of the species. We contacted Eric Eaton and here is his concise reply: “I can actually help! The image is of a Larger Elm Leaf Beetle, Monocesta coryli. Looks just like the image we will be using in our field guide in fact:-) The insect is not uncommon, but some years can be better than others. The ones I have collected did not have any black markings, so the species is apparently quite variable in its coloration. The pear-shape is quite distinctive and consistent, however. It is indeed a chrysomelid. Eric “

Letter 11 – Larger Elm Leaf Beetle

black and gold beetle in SC
Can you tell what this black and gold beetle is? Found in central SC. Looks similar to Cucumber beetles I see on your site but not quite.
Regards,
Robert Shannon

Hi Robert,
We believe this is a Larger Elm Leaf Beetle, Monocesta coryli, one of the Skeletonizing Leaf Beetles. We found it on BugGuide.

Letter 12 – Larger Elm Leaf Beetle

Bug Identifcation
Location: West Virginia
July 10, 2011 12:23 pm
My son found this beetle. We searched on this site and could not find one listed. Here is a photo.
Signature: Ryland

Dear Ryland,
We quickly identified your beetle as a Larger Elm Leaf Beetle, Monocesta coryli, by matching it to a posting on BugGuide, also from West Virginia. There is a note that this is a variable species, and it might have dark spots, light spots, or like your individual, no spots.

Letter 13 – Larger Elm Leaf Beetle

Subject: Identify this nettle please?
Location: Virginia USA
July 9, 2017 1:45 am
This was found in central Virginia, USA. I’ve attached photos. Thanks so much!
Signature: Samantha

Dear Samantha,
Is there an elm tree nearby? This is a Larger Elm Leaf Beetle, Monocesta coryli, which we identified on Getty Images and verified on BugGuide.

Letter 14 – Larva from Peru might be Leaf Beetle Larva

Subject: larva from Peru
Location: Peru; near Iquitos
March 13, 2014 5:49 pm
Hello, this one is really a quest. I have no idea what is on the photo. I think its some larva from some incest. However which one.. I dont know. Any help ll be appreciated 🙂
Signature: Jiri Hodecek

Hi Jiri,
We really haven’t had time to research this request, but we believe it may the the larva of a Leaf Beetle in the family Chrysomelidae. The somewhat similar looking Spotted Tortoise Beetle larvae pictured on the South African Photographs website support our speculation.

Letter 15 – Imported Willow Leaf Beetle

Subject: Willow eating bug
Location: Eastern Pennsylvania, USA
June 3, 2014 4:49 am
Our willow tree leaves are being eaten away by this strange creature. Please help identify it.
Signature: David

these are predatory lady beetle larvae and they feed on aphids, not leaves.

Ah! So the aphids should be somewhere about eating the leaves then?
Sincerely,
David

no, aphids suck the juices from plants

I’ll try again…this little thing is definitely eating the leaves on my Willow tree.
Sincerely,
David

Bingo David,
This is the larva of a Leaf Beetle in the family Chrysomelidae, and we will attempt to identify it to the species level for you. Willow is a popular food plant among insects, including species of butterfly caterpillars, moth caterpillars and aphids. We seem to recall a Willow Leaf Beetle identification in the past and we were correct, however, the larva pictured on BugGuide looks nothing like your Leaf Beetle Larva. We believe we found a larva that matches yours identified on the Evolution in Structured Populations University of Vermont website, but the are only identified generally and this behavior is described: “Imported willow leaf beetles are group foragers. Larger groups survive better than small groups.” The University of Minnesota Extension website identifies the Imported Willow Leaf Beetle as Plagiodera versicolora and states: “Adult beetles make notches or holes in leaves/ Larvae windowpane leaves, i.e. they feed on the upper surface of the leaves between the veins. Prefers willows and poplars, especially weeping willow. Adults are bluish-black to greenish blue, about ⅛ – ¼ inch long. Larvae are dark, almost black and about ¼ inch long.” According to BugGuide, you are in the range of the Imported Willow Leaf Beetle.

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.