June beetles are a common sight in North America during the warm summer months. With their distinctive metallic green color and buzzing flight pattern, they often capture the attention of gardeners and nature enthusiasts alike. But the question arises, are they harmful?
The answer to this question largely depends on the stage of a June beetle’s life cycle. Adult June beetles, such as the Green June Beetle, are typically harmless and feed on fruits, nectar, and foliage. They may cause minor damage to plants, but are generally considered non-threatening to gardeners.
However, it’s the June beetle larvae, also known as white grubs, that can cause considerable damage to the roots of grass, broadleaf weeds, trees, and shrubs. In some cases, these grubs require 2 or 3 years in the soil to fully develop, gradually causing more extensive harm to plants as they grow. To keep your plants healthy and free from damage, it’s essential to stay vigilant and manage such pests effectively.
Understanding June Beetles
Life Cycle
- Eggs: Female beetles lay eggs in the soil.
- Larvae (grubs): Feed on roots; grow from 1/4 inch to 2 inches long1.
- Pupae: Brown and 1/2 inch long1.
- Adults: Metallic green or brown; nearly 1 inch long1.
June beetles complete their life cycle in 2-3 years2.
June Beetle Species
Some common June beetle species include:
- Green June Beetle (Cotinus nitida)1
- May Beetle (Phyllophaga spp.)3
- May Bug (European Chafer, Amphimallon solstitiale)
Geographical Distribution
June beetles are commonly found in:
- North America1
- Europe (May Bug)
They are attracted to light and have six legs3.
Pros of June Beetles:
- Can be a food source for birds and other animals
Cons of June Beetles:
- Larvae/grubs can damage plant roots2
- Can be a nuisance for gardeners and homeowners
Control Methods:
- Introduce beneficial nematodes (Heterorhabditis bacteriophora)4
Comparison Table: Green June Beetle vs. May Beetle
| Feature | Green June Beetle | May Beetle |
|---|---|---|
| Adult color | Metallic green with bronze edges | Light tan to reddish-brown |
| Larval appearance | Cream-colored | Cream-colored |
| Time to complete life cycle | 2-3 years | 2-3 years |
The Harmful Impact of June Beetles
Damage to Plants and Gardens
June beetles can cause significant damage to plants and gardens. They feed on the leaves of various plants, such as roses and other flowers. This can lead to:
- Stunted plant growth
- Reduced flowering
- Increased susceptibility to diseases
Effects on Lawns and Yards
June beetles also impact turfgrass, commonly found in lawns and yards. Their grubs feed on the roots of grasses, which can cause:
- Patches of dying or dead grass
- Loose turf that is easily pulled up
- Uneven lawn surfaces
For example, a well-manicured lawn might suddenly show signs of infestation, such as brown patches or dead grass.
Underground Impact
The underground impact of June beetles is mainly due to their larvae, or grubs. These grubs feed on various plant roots and can cause significant soil issues, such as:
- Compromised soil structure
- Decreased nutrient availability for plants
- Increased erosion risk
Grubs can grow up to 2 inches long, making them quite damaging to plant roots and soil.
Impact on Trees and Shrubs
June beetles may be particularly harmful to trees and shrubs in gardens and landscapes. They can cause:
- Defoliation of leaves
- Weakened branches
- Slow tree and shrub growth
Crops like corn may also suffer from June beetle infestations, and their feeding can lead to crop loss or poor yield.
Comparison of June Beetle Damage:
| Area of Impact | Examples of Damage |
|---|---|
| Plants | Stunted growth, reduced flowering |
| Lawns | Dead grass, loosened turf |
| Soil | Compromised nutrient availability |
| Trees & Shrubs | Defoliation, weakened tree structure |
While June beetles can be quite damaging, understanding their impact on various aspects of gardens and landscapes can help in their monitoring and control.
How to Manage June Beetle Infestations
Cultural Controls
- Hand-picking: Remove adult beetles and larvae by hand, especially during dusk when they are most active1.
- Trapping: Attract beetles with light traps or fruit-based traps2. Dispose of trapped beetles daily.
Biological Controls
- Predators: Birds, toads, snakes, moles, and skunks can help control beetle populations by feeding on larvae and adult beetles4.
- Nematodes: Introduce beneficial nematodes (Heterorhabditis bacteriophora) to target the white grub stage of the life cycle5.
Chemical Controls
- Insecticides: Apply insecticides with active ingredients such as carbaryl or trichlorfon when grubs are feeding3.
- Preventatives: Use products containing imidacloprid or halofenozide to prevent beetle infestations6.
| Method | Pros | Cons |
|---|---|---|
| Cultural | Non-toxic, minimal environmental impact | Can be labor-intensive |
| Biological | Natural, minimal chemical use | Slow-acting, predators can be unreliable |
| Chemical | Fast-acting, effective | Can harm non-target organisms, potential health risks |
Note: Always consider the potential impact on pets and human health before using chemical controls.
Prevention Strategies and Tips
Lawn Care
A healthy, well-tended lawn can resist June beetles and their larvae. Implement these tips:
- Regularly water your lawn, especially during dry spells.
- Mow at the appropriate height for your grass type to promote healthy growth.
- Fertilize with the right nutrients and amounts for your turfgrass species.
Using nematodes like Heterorhabditis bacteriophora can be beneficial to control white grubs, the larvae of June beetles, in your lawn.
Garden Maintenance
Prevent damage to your plants by following these steps:
- Regularly inspect plants for beetles and their larvae, removing them by hand if necessary.
- Keep your garden free of debris, which can provide shelter for beetles.
- Plant beetle-resistant plant varieties.
For example, Japanese beetles avoid plants with strong odors, like marigolds and garlic.
Monitoring and Trapping Methods
To monitor and trap June bugs, consider these methods:
- Commercial beetle traps can be used to control adult beetles.
- Hand-pick beetles off plants and drop them into a bucket of soapy water.
- Make a homemade June bug trap with molasses and water.
| Method | Pros | Cons |
|---|---|---|
| Commercial beetle traps | Effective, easy to use | Can be expensive, may attract more beetles |
| Hand-picking | Chemical-free, inexpensive | Time-consuming, not suitable for large areas |
| Homemade June bug trap with molasses and water | Inexpensive, eco-friendly | Less effective than commercial traps |
Remember to always practice moderation when using pesticides, as excessive use can harm your garden’s health and the environment. Organic options like milky spore can also help control grub populations.
Footnotes
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 – June Beetle from Turkey
Location: Marmaris, Turkey (south-west)
July 17, 2011 3:51 am
Hello Bugman,
She has long antennas with wing covers. Hard body, brown with white spots on her. She weeeeks when touched. Otherwise she is quite quiet.
Size: as big as a small finger
Thank you so much,
Signature: don’t mind.
Dear don’t mind,
Your June Beetle is Polyphylla fullo, and she is a he based on the antennae. The male has much grander antennae which he uses to locate the female. You can see a similar photo on BioLib.
Letter 2 – Lined June Beetle
Location: Aurora, CO
July 18, 2013 10:45 pm
Hello,
My husband spotted this beauty on the side of our house this evening. I’ve looked up several feather-horned beetles, but can’t find one quite like this one. Would you have any ideas?
Signature: Intrigued in CO
Dear Intrigued in CO,
This is a Lined June Beetle in the genus Polyphylla. We are not certain if it is our Bug of the Month, the Ten Lined June Beetle, or a closely related species. Your individual is a male and he uses those highly developed antennae, which do resemble eyelashes, to locate females by sensing their pheromones.
Letter 3 – Lined June Beetle
Geographic location of the bug: NC mountains, Lake Toxaway
Date: 07/14/2018
Time: 03:46 PM EDT
Your letter to the bugman: I thought this was a ten lined june bug, but they’re apparently only found out west. I’m in NC. It hisses, so what is it?
How you want your letter signed: Chris
Dear Chris,
You are absolutely correct that this is not a Ten Lined June Beetle, Polyphylla decemlineata, a western species, however it is still a Lined June Beetle in the genus Polyphylla. The large antennae indicates it is a male. The hissing sound you heard is made when the beetle rubs its body parts together, a process known as stridulation. We believe your individual is a species with a BugGuide range of “Virginia south through the Great Smokies to Louisiana” and with no common name other than the general genus name of Lined June Beetle, Polyphylla comes, based on this BugGuide image, but we would not rule out that it might be the Variegated June Beetle, Polyphylla variolosa, based on this BugGuide image. Both species are in your geographic area. Apparently these species can be difficult to differentiate, as this BugGuide posting proves.
Letter 4 – June Beetle Pupae
these baby bugs were found underground in nothern Arizona. there were ten lined june bug larva near the same area. we have some kind of red june bettles around that look alot like these. perhaps that is what they are? (I sent you the same photo before but I can’t find it on your site, so here it is again)
D. Pipkin
Hi D.,
These are Scarab Beetle Pupae, and the Red June Beetles you mention are a very likely candidate.
Letter 5 – Hammond’s Lined June Beetle
Location: Northeast Iowa
July 7, 2016 11:34 pm
Hi! My fiancé and I heard a loud winged buzzing in our front window- sounded just like a large wasp- and our cat caught this guy. When my fiancé picked it up in a napkin to release/inspect it is made a screeching sound- almost like it was spitting a liquid against the napkin but it wasn’t. We put it in a ventilated jar to check it out and try to research it, which brought me to this site. I’m very curious if you all have any ideas? I’m in Salix northeastern corner), Iowa. It’s early July. It is medium brown colored, hard shell wings but then under them are wings that look very similar to a wasp. It has a furry chest and butt area, looks slightly stripped on there too. Almost looks like the butt ends in a stinger, but can’t tell. The antenna have a fan-like quality. The screeching/spitting/screaming sound was pretty loud when it made it but it didn’t replicate it in the jar. Thanks so much for the help! Also this was very late at night- around 11pm.
Signature: M and J
Dear M and J,
Though its markings are much more subtle than the Ten Lined June Beetle, your Scarab is nonetheless a member of the Lined June Beetle genus Polyphylla. We believe we have correctly identified it as a male Hammond’s Lined June Beetle, Polyphylla hammondi, thanks to images on BugGuide. Males in the genus have fanlike, or more correctly “flabellate” according to BugGuide, antennae. According to BugGuide it is: “widespread in w. US, with isolated populations east of the Mississippi River.” The “screeching sound” you describe is made by rubbing body parts together and it known as stridulation. Many beetles will stridulate when handled.
Letter 6 – June Beetle
Any idea what bug this is? I found it flying outside near the top of my birch tree.
Thank you
Hal
Hi Hal,
You have a species of June Beetle. Your photo isn’t the best quality and it is difficult to tell if the color is really golden or if it is a reflection from your flash.
Letter 7 – June Beetle
Location: Toronto, Ontario, Canada
June 2, 2014 6:11 pm
I found this beetle crawling up the wall towards my porch light, I think it in the Genus Dichelonyx. I would love to know what species it is and any info you may have.
Signature: Gary Yankech
Dear Gary,
We believe you have correctly identified this June Beetle as a member of the genus Dichelonyx based on this and other images posted to BugGuide. We also received several other inquiries from you, and we want to thank you for using a separate form for each submission. Alas, we are not entomologists and we do not have any formal training in entomology, so we are not really qualified to attempt a species identification for you, but perhaps one of our readers will be able to provide you with more specific information.
Letter 8 – June Beetle from China
March 24, 2010
I sent you some photos of this odd looking Chinese insect a few days ago. Did you get them? I swear, it’s not a Photoshop job. It has eyes like Paul Newman and more gold leaf than a temple. What is this thing? I have dozens more photos. Let me know if you want them. Thanks!
Mike J.
Dongguan, China
Dear Mike,
We did not see your earlier submission. We are not certain of the species, but we will post your June Beetle in the hopes that one of our readers can make an identification.
Hi Daniel,
Thanks for your reply. Here are the shots I originally submitted and the corresponding text.
Hope you can figure it out. There are lots of these guys flying around here in the evening; similar to Junebugs back in the US midwest.
Mike
Beetles in China
I see these frequently in South China. They fly in the evening like June Bugs. The golden shell, big blue eyes and fern-like feelers are pretty cool. This guy found his way inside tonight. Wouldn’t let him leave without some photos. Thought you’d enjoy these.
Mike J.
Dongguan, China
Letter 9 – June Beetle from the Netherlands
Location: Wassenaar, Zuid Holland, Netherlands
July 4, 2011 12:44 pm
I took this photo outside my front garden. I live in south Holland, Netherlands, Europe.
When I poked it gently with my door key it made a noise, I think coming from its rear but not sure.
It was not interested in moving and I found it again trying to dig into the dry dirt. It was about 3.5 – 4 centimetres long.
Signature: Rosie
Hi Rosie,
This is sure a pretty Scarab Beetle, actually one of the June Beetles. We located it on the Photo Gallery of Beetles website, and had to view all the thumbnails, where we learned it is Polyphylla fullo. There are some nice photos here, and BioLib also has a good photo. According to the Free Dictionary: “The beetle is distributed in middle and southeastern Europe; in the USSR it is found in Byelorussia, the Ukraine, and the Volga Region. The beetles fly in July evenings and nights; they feed on the leaves and needles of trees. The females deposit their eggs in the soil. Development continues for three years; in extremely dark places, development may take up to four years. Young larvae feed on humus and the roots of herbaceous plants; older larvae gnaw through the roots of shrubs and trees and cause desiccation of the plants.”
Letter 10 – june beetle infestation
Here’s a picture of one of our trees in central NM that is covered with these beetles. I think they are June bugs comparing them to a picture ;on your site. For 3 nights we have been swatting the bugs inside and just noticed tonight that all our pine trees are completely covered with these guys chewing the needles. Do you have any suggestions on how to get rid of them? We had lots of birds here but none now that the bugs are here. Much appreciate your speedy reply.
Sally Beers
Hi Sally,
It is dificult to tell exactly, but your photo does seem to indicate a June Beetle infestation.. As you must realize, they are very fond of eating pine needles. Sorry, we have no erradication advice. You could try trapping them at night when they are attracted to lights.
Daniel,
Thanks for getting back so quick. If you are interested, here’s what we did:
At night while all the beetles were munching away we shook the tree and gathered them in a tarp. When the sun came up they dropped from the trees and began crawling to our house. Sprayed a bit on the edges of the entry way and swept a lot up. Guess they are eating by night and sleeping in our walls by day. Today will go for bug zappers to try and get some more. Thanks so much for your help.
Sally
Letter 11 – Lined June Beetle
Tue, Jun 9, 2009 at 11:17 AM
this beetle, probably a bit more than two or three inches was in our garage. He was struggling on his back. When I tried to turn him over, he hissed at me. I finally picked him up and put him out in the front yard. Can you tell me what he is?
Linda Williams
Marble Falls, Texas
Hi Linda,
This is one of the Lined June Beetles in the genus Polyphylla, probably Polyphylla occidentalis, though species identification may be difficult. There are numerous matching images posted to BugGuide. The genus page on BugGuide indicates: “Food Adults feed on tree foliage, thus sometimes called ‘chafers’.
Life Cycle Eggs are laid on soil near host plants. Larvae hatch, burrow down and feed on roots of shrubs, trees, require 2-3 years to reach maturity. Pupation is in underground chambers. Adults come to lights. ” These beetles make squeaking noises when handled.
Letter 12 – Lined June Beetle
July 14, 2009
I have lived in Oklahoma all my life and have never seen one of these bugs in my 30 years in this state. They are about and inch and half long with a striped abdomen. They hiss quite loudly when disturbed. And the antler like formations on the head are very interesting. Is this a native species to Oklahoma.
David Gerlach
Oklahoma City, Ok. USA
Hi David,
This is one of the Lined June Beetles, probably Polyphylla occidentalis. You can see some matching images on BugGuide. He has some pretty impressive antennae.
Letter 13 – Lined June Beetle
Location: Socorro, NM, USA
July 19, 2010 8:30 am
I encountered this fair-sized beetle on our door upon taking out some trash. It was kind enough to stay put as I ran and grabbed the camera. Sorry for the relatively poor quality; it was dark and my camera has a tendency to over-saturate with the flash. It was a little over an inch long, by my estimation.
Grady Owens
Hi Grady,
As you indicated, your photo is not ideal quality, however, we are confident that this is a Lined June Beetle in the genus Polyphylla. We cannot, however, commit to an exact species identification. Perhaps it is Polyphylla hirsuta, a species that BugGuide reports from nearby Arizona.
Letter 14 – Lined June Beetle
Location: NW Montana, USA
July 17, 2017 12:15 pm
Found two of these large (a little more than an inch long) striped beetles at a service station in the Flathead Valley near larch and pine forest in NW Montana. Probably drawn in by lights the night before. Can you help me ID?
Signature: Dorinda Troutman
Dear Dorinda,
This is a Lined June Beetle in the genus Polyphylla, but we are not comfortable providing a species name as there are many similar looking members of the genus, and BugGuide, our favorite source for North American identifications, is currently unavailable.
Daniel:
I very much appreciate your prompt reply with an answer. My husband told me it was a June beetle when I showed him the photo yesterday, and I had seen somewhat similar ones, but not exactly the same, on your website. My beetle did not show antennae and its head and body were two different colors. I’m happy with the general name.
Thank you again,
Dorinda Troutman
Letter 15 – Lined June Beetle
Geographic location of the bug: Sylmar, California
Date: 10/02/2017
Time: 10:15 PM EDT
What kind of moth is this? I really want to know. Thank you.
How you want your letter signed: Anywhere
Dear Anywhere,
This is not a moth. It is a Lined June Beetle in the genus Polyphylla, most likely the Ten Lined June Beetle, a common species found during the summer in Southern California. This is late in the season for a sighting. BugGuide does include September sightings in both Arizona and California, but there are no reported October sightings.
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