Are Scarab Beetles Dangerous? Unveiling the Truth

Scarab beetles are a diverse family of insects found in various environments, and their interactions with humans can vary greatly.

Some species of scarab beetles, such as dung beetles and chafers, are known to have an important ecological role by aiding in decomposition and providing a natural form of pest control.

Other species, however, can be harmful to plants and gardens due to their feeding habits, but they’re generally not considered dangerous to humans.

The grape pelidnota, for instance, is a type of scarab beetle that is prevalent in wooded areas during the late spring and summer.

Although they might cause damage to grapevines and other plants, they don’t pose any direct threat to humans or their pets.

Similarly, predatory beetles like rove beetles, soldier beetles, and tiger beetles are beneficial for controlling other insect populations, even though they might bite if handled.

Overall, scarab beetles can have both positive and negative impacts on their surroundings, but any potential danger is usually limited to plants and other insects.

Scarab Beetles Overview

Species and Classification

Scarab beetles belong to the family Scarabaeidae within the order Coleoptera.

They are a diverse family of beetles that are found in various environments across the globe, including North America.

Some common and well-known types of scarab beetles are June bugs and Old House Borers.

Some characteristics of scarab beetles include:

• Oval or elongated body shape
• Stout and usually rounded backs
• Clubbed antennae with segments that can press

Scarab beetles have been associated with the concept of rebirth in ancient cultures due to their unique life cycles and habits of rolling dung into balls.

Life Cycle

The life cycle of scarab beetles consists of four stages: egg, larva, pupa, and adult.

• Eggs: Female beetles lay eggs in different environments depending on the species, often in soil or decomposing matter, like carrion.
• Larva: The larvae are commonly referred to as grubs. They are C-shaped, usually whitish, and have brownish or black heads with three pairs of legs. Larvae live underground or in protected places and consume organic matter.
• Pupa: After reaching a certain size, the larvae pupate, transforming into adult beetles in a protected space like soil or wood.
• Adult: Adult scarab beetles emerge from their pupal stage and begin searching for food and mates. Some species are active at night while others during the day.

Life Stage	Habitat	Diet
Egg	Soil/Decomposing matter	None
Larva	Underground/Protected places	Organic matter
Pupa	Soil/Wood	None
Adult	Various, depending on species	Plant/organics materials

Though they can be considered pests in some situations, scarab beetles play a significant role in the ecosystem, helping recycle nutrients by consuming decomposing matter.

Are Scarab Beetles Dangerous?

Potential Pests

Scarab beetles can sometimes be considered pests as certain species are known to cause damage to plants and trees.

For example, the spotted grapevine beetle feeds on grapevines and can harm plants in wooded areas.

Some scarab beetles can also affect the health of trees and garden plants.

They may harm the environment by destroying vegetation, which can lead to soil erosion and degradation.

Beneficial Species

However, not all scarab beetles are harmful, and some species are actually beneficial to the environment.

These species act as scavengers, helping to break down and recycle organic material.

Some examples of beneficial scarab beetles include dung beetles and burying beetles, which play a vital role in maintaining the balance of ecosystems by decomposing animal waste and dead animals.

Here’s a comparison table highlighting the key differences between the two types of scarab beetles:

Characteristic	Pest Species	Beneficial Species
Environmental Impact	Harmful to plants, trees, and garden plants	Positive, helps recycle organic material
Health effects	Can damage plants	No known health concerns
Role in ecosystem	Negative, destroys vegetation	Positive, maintains balance

In conclusion, while some scarab beetles can be harmful to plants and the environment, others are beneficial species that play a crucial role in maintaining ecosystems.

It’s essential to accurately identify the beetle species and consider their impact before taking any actions.

Identifying Scarab Beetles

Physical Characteristics

Scarab beetles are a diverse group of insects with varying physical features, but some common characteristics can help identify them. Adult scarab beetles generally possess:

• Oval-shaped body
• Head and thorax may vary in color
• Six legs
• Wing covers, often dark or light brown
• Sometimes, iridescent colors

Scarab beetle larvae, on the other hand, are distinct with:

• Legless bodies
• Cream-colored, segmented appearance
• Round heads, which slant downward in later stages of development

Behaviors

Scarab beetles have unique behaviors that set them apart from other insects:

• Adult beetles are often attracted to light.
• Larvae, also known as grubs, live in the soil and feed on organic matter or plant roots.
• Certain species, like the hoplia beetle, are active from late March to May and cause problems by feeding on light-colored blossoms.

Habitat

Different types of scarab beetles can be found in varying environments:

• Grape pelidnota beetles are commonly found in wooded areas and sites next to these areas.
• Hoplia beetles are usually seen in gardens, feeding on flowers or foliage.
• Sawyer beetles are associated with dead or dying trees, making their habitat more forest-focused.

Type of Beetle	Habitat
Grape Pelidnota	Wooded areas and sites next to these areas
Hoplia	Gardens with flowers and foliage
Sawyer	Dead or dying trees in forests

Scarab Beetles and Human Interaction

Effects on Agriculture

Scarab beetles can have both positive and negative effects on agriculture.

For instance, grubs, which are the larval stage of scarab beetles, may damage the roots of grains and corn when present in large numbers, leading to reduced crop yield.

On the other hand, many scarab beetles are beneficial as they help in breaking down organic matter and recycling nutrients in the soil.

Example:

• Japanese beetles are known to attack over 300 species of plants, including ornamental flowers and fruits, causing significant damage to agriculture.

Historical and Cultural Significance

Scarab beetles have long-held cultural and historical significance in various societies.

For example, in ancient Egypt, they were considered sacred and associated with rebirth.

Artifacts:

• Scarab beetle amulets were widely used by Egyptians for protection and considered a symbol of resurrection.

Science and technology:

• Scarab beetles have influenced the development of robotics and inspired breeding technologies in agriculture due to their unique characteristics.

Comparison Table:

Aspect	Positive	Negative
Agriculture	Organic matter breakdown, recycling nutrients	Attacks plants, damages grains and corn
Historical Significance	Symbol of rebirth in ancient Egypt	N/A
Science and Technology	Robotics, breeding technologies	N/A

When threatened, scarab beetles may use their strong mandibles to pinch as a defense mechanism.

Although they are not considered dangerous to humans, they can cause mild discomfort when pinching the skin.

However, it’s essential to remember that not all scarab beetles exhibit this behavior.

Conclusion

Here is a possible conclusion for the article:

Scarab beetles are a diverse group of insects that have fascinated humans for centuries.

Most scarab beetles are harmless and beneficial to the environment, as they feed on dung, decomposing organic matter, or plant materials.

Some scarab beetles may cause minor damage to crops or gardens, but they can be controlled by natural predators or cultural practices.

Only a few scarab beetles are considered pests or vectors of diseases, such as the Japanese beetle, the oriental beetle, and the dung beetle.

These can be managed by using traps, insecticides, or biological agents.

Reader Emails

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

Letter 1 – Chinese Rose Beetles in Hawaii

Beetles decimating my rose bushes
Location: Honolulu, Hawaii
July 10, 2011 3:07 pm
In about the time frame of the last week, my rose bushes have gone from healthy looking bushes to nearly bare stalks (with the exception of the thorns and a few blooms).

The leaves that are left are being steadily eaten, but until today I hadn’t caught any culprits. I am guessing the beetles that I found this morning when I went out to prune are the ones doing the dirty work.

I’m assuming they come out at night because normally by morning they are gone, and the ones that I do have photos of I do believe are quite dead.

Not sure if they’re dead, or if they just are extremely laid back beetles, because they stayed on the leaves as I was pruning them from my bushes. The beetles are about a 1/2 inch long at the most, and are a lighter brown in coloration. I live in Honolulu, HI.
Signature: Tina

Hi Tina,
You have an infestation of the invasive exotic Chinese Rose Beetle, Adoretus sinicus, which we found on the Insects of Hawaii website as well as the Guam Insects website.

Letter 2 – Cotalpa consobrina

Golden Beetle
I just found a beetle that looks very similar to a June beetle but is more pale golden in color and does not have long antennae. It’s topside looks somewhat like the Hercules or Unicorn beetle without the spots.

It also has somewhat of a tiny triangular shape at the top intersection of its wings and its head somewhat like the Eastern Hercules Beetle has. It is kind of shiny as though the body is armored.

I have drawn a picture of it but the picture does not really do it justice as the green you see on its wings and behind the head is more of a dotted green hue instead of stark lines.

In fact I just looked at it again and the color behind the head where you see the two brown blobs is morelike two B’s, very lightly brownish hued, facing each other The white dots you see represent the shine on it.

When flipped over, it is ribbed and looks more the color of a brown colored honey or horehound and its legs have somewhat fuzzy hairs on the outside edges while the chest section is fuzzy (somewhat like a bee is fuzzy).

It also seems to be somewhat fuzzy under the lower portion of the wings. The hind legs get lighter at the upper portion of the leg. The undertail section is more closely ribbed than the upper section.

Centered between its second set of legs and back legs is somewhat of a diamond shape with a line going through the center of the diamond (Head Tail). Your help in identifying this beetle would be tremendously appreciated!
Sincerely, Diana Isham, Grantsburg Wisconsin

Hi Diana.
We got another letter from New Hampshire reporting a similar beetle. We have decided it is probably Cotalpa lanigera which is approximately an inch long and entirely yellow with a metallic luster. It occurs near catalpa trees. It could be your beetle.

Thank you my friend! I looked up Cotalpa lanigera and thought momentarily that it might be it because it looks very much like it but its wings also looked too white.

I then did a bit of research, found it on the following website and was delighted to find a lovely photo of my beetle just below Catalpa lanigera. It is called Cotalpa consobrina and is a native Arizonan like myself!

I am so amazed! I lived in Arizona for the first 15 years of my life and never saw one of these! And now I’m wondering if it’s a native only in Arizona, and if so, how did it end up here in Wisconsin?

Hi Diana,
We haven’t been able to locate any information on the extent of the range of Cotalpa consobrina.

Letter 3 – African Sun Beetle found in England!!!

Subject: Unknown beetle
Location: Warsash, England
August 24, 2016 11:15 am
Found this beauty in our back garden today, in Warsash on the south coast of England. It was very hot here today and he appeared to be resting in the shade. Can’t find him in our Beetle books!
Many thanks
Signature: Tracy Dukes

Dear Tracy,
Our first impression proved correct:  This is not a native species in England.  We believe we have correctly identified your Scarab Beetle as a Sun Beetle, Pachnoda marginata, a species that according to Shutterstock is:  “a beetle from the subfamily Cetoniinae (Scarabaeidae) that lives in west and central Africa.

They are used as food for terrarium animals.”  Perhaps this individual escaped from someone who is raising them in captivity.  According to BioLib, it is a Congo Chafer. 

According to the Global Biodiversity Information Facility:  “Pachnoda marginata is a beetle from the subfamily Cetoniinae with a large number of subspecies that lives in west and central Africa.  They are sometimes used as food for terrarium animals.”

Letter 4 – Asiatic Garden Beetle

Beetle found eatting vegetation of and mating on Ailanthus altissima “Tree of Heaven” plant
Tue, Dec 2, 2008 at 5:00 AM
I was studying the Ailanthus webworm this summer in Richmond Virginia, and started doing night time observations on the bug colonies of Ailanthus altissima the “Tree of Heaven” plant.

I had started to notice large quantities of herbivoiry other than that of the webworm and when I started doing the night time observatioins, I found this beetle feeding and mating (while feeding it seemed) on the Tree of Heaven plant creating the herbivory patterns that I was curious about.

It never fed on any of the surrounding plants, and its patterns of herbivory were seen very widespread and very distinctively around the Richmond VA area.

I am very interested to see what this beetle is, because it seems like it may be a specialist to this plant which is something I am looking into.

So if you could help me out, I’d really appreciate it! The picture is a little bit out of focus because of the night time (and i’m not the best photographer), but let me know what you think, this is very interesting!
Will
Richmond Virginia

Hi Will,
According to BugGuide, the Asiatic Garden Beetle, Maladera castanea, “Feeds at night on leaves of roses, chrysanthemums.”

There is no indication that it feeds on Ailanthus leaves, but this native of Eastern temperate Asia was “Introduced and established on east coast of United States.”

Then we located another website on the Ailanthus tree that indicates: “The Asiatic garden beetle (Maladera castanea) feeds on numerous plants during night flights, including ailanthus. ”

We hope that you are working towards discovering a damaging agent that will eliminate the entire population of Ailanthus trees from the New World.

In our opinion, the Ailanthus tree is the most important invasive exotic plant in North America, and we are waging our own campaign to obliterate the population in our rustic Mount Washington, Los Angeles hillside.

Letter 5 – Bee Chafer from Austria

A bee, perhaps?
Location: Upper Styria, Austria
June 30, 2011 6:55 am
Dear Bugman, I came across this eyecatching creature June 9 along the Enns River between Wörschach and Niederhofen, Austria.

The weather was overcast and cold, hovering right around 60˚F, but I had the feeling that if it had been warmer, this little fella would have been buzzing from flower to flower.

Do you have an identification for it? Thanks in advance!
Signature: N. Fritz

Dear N. Fritz,
We believe we have correctly identified this Scarab Beetle as a Bee Chafer, Trichius rosaceus or Trichius fasciatus, based on Rob Coleman’s photos on ISpot.  The Global Species website has some very similar photos.  The harmless Bee Chafer probably derives some benefit from mimicking a stinging bee.

Thanks, Daniel!  Is it the first bee chafer to be featured on What’s that Bug?  If so, I’m very honored!  Condolences on Lefty, but I’m glad to hear his legacy will live on.

Thanks.  We do not turn up any matches on our site for Trichius, so this is probably a genus first on our site, however we do have some similar North American species.

Letter 6 – Black Snail Beetle from Australia

Black Nail Beetle – Brisbane – Queensland
February 20, 2010
hello again WTB-ers 🙂
Here is another first for WTB and yet another curious bug i have come across – this time in my yard! This is the Black Nail beetle ( Repsimus manicatus) from the scarabaeidae family.

Its got the most “muscular” thighs i have ever seen on a beetle, and its legs end in hooks – certainly felt very funny walking on me!

Wish it had stuck around longer so i could take more photos (it must have had some important muscular bug business to attend to) – thought you may like to add it to your collection 😀
Dreaded Bug Queen
Ashgrove – Queensland – Australia

Dear Dreaded Bug Queen,
Thank you so much for sending us this awesome set of photos, and also for providing us with an identification.  The Brisbane Insect Website has some nice photos, but not much helpful information on the species.

The Hunter Valley Backyard Nature website classifies the Black Snail Beetle as a Christmas Beetle and has some wonderful images of mating activity. 

BioLib has the more scientific taxonomy of placing the Black Snail Beetle into the family of Shining Leaf Chafers, Rutelidae.

Letter 7 – Carrot Beetle we believe

Subject:  What kind of beetle is this?
Geographic location of the bug:  Abingdon, MD
Date: 06/21/2019
Time: 06:05 PM EDT
Your letter to the bugman:  First day of summer and the weather is perfect – 80 degrees and no humidity! I found this by my ornamental pond today when I was checking on the gazillion tadpoles we have growing in there.

We normally don’t get beetles this big. It’s about 1.5″ long and fat! It’s bottom and underside are reddish in color. It didn’t seem like it could fly and I don’t know if it even had wings.

Very cute bug though! It’s too early for the Japanese beetles which usually come in July. Just wondering what it is. Thanks!
How you want your letter signed:  C. Baker

Dear C. Baker,
We believe this Scarab Beetle is a Carrot Beetle, Tomarus gibbosus, based on images posted to BugGuide.  There are additional images on iNaturalist.

Letter 8 – Bug of the Month September 2015: Odor of Leather Beetle

Subject: Large beetle – central Ontario
Location: Parry Sound, ON
August 31, 2015 3:40 am
Trying to ID this beauty. Spotted in a well-treed residential area adjacent to a forest. Thanks!
Signature: Jason

Dear Jason,
We verified the identity of your Scarab Beetle as a Hermit Beetle or Odor of Leather Beetle, Osmoderma eremicola, thanks to the images posted on BugGuide where it states the habitat is:  “rotten logs in woodlands and orchards; adults nocturnal, come to lights.”

Cool. It’s so big. Thanks!

It is the time of the month to select a Bug of the Month for September 2015, and because we are intrigued that BugGuide indicates that the Hermit Beetle gets its other common name “for strong odor of ‘Russian Leather,'” it is a worthy subject to feature next month. 

The Backyard Arthropod Project notes:  ” The thing is, the way people talk about it, the odor is supposed to be really strong and noticeable, but with this one it is practically nonexistent.”