Big Headed Ground Beetle: Quick Facts and Essential Info

October 26, 2023September 3, 2023 by Daniel Marlos, Piyushi Dhir

The Big Headed Ground Beetle is a fascinating insect that plays a crucial role in controlling pest populations. These beetles belong to the family Carabidae and can be found in various agricultural and garden settings. With their unique appearance and beneficial attributes, it’s worth understanding what sets this beetle apart from other insects.

These beetles are small to moderately sized, ranging from 1/8 to 1/2 inches long, with some species even reaching up to 1 inch in length. They have a distinct flattened shape and noticeable mandibles (jaws) that make them easily recognizable. Their iridescent coloration, displaying different hues depending on the angle of light, adds to their allure.

Big Headed Ground Beetles act as essential predators in their ecosystems. They help maintain the balance by preying on other insects, specifically pests that can negatively impact plants and crops. This natural method of pest control is advantageous since it reduces the need for chemical treatments in gardens and farmlands.

Big Headed Ground Beetle Identification

Color and Appearance

The Big Headed Ground Beetle, also known as Scarites subterraneus, has a distinct appearance, making it easy to identify. These beetles typically have a:

Color: Black or dark brown, with a shiny and iridescent surface
Body: Hard, flattened body with well-developed, powerful mandibles

Size and Anatomy

Big Headed Ground Beetles are moderate in size, possessing some key anatomical features:

Size: About 1/2 inch to 1 inch in length
Legs: Long, strong legs adapted for rapid movement
Antennae: Elongated and prominent, aiding in sensing their environment

Distinguishing Features

The distinguishing features of the Scarites genus, which includes the Big Headed Ground Beetle, are:

Enlarged, flattened head with ridged and bulging eyes
Pronounced, tooth-like projections on the sides of the thorax

As part of the Scarites genus, the Big Headed Ground Beetle shares these traits.

Here’s a comparison table of Big Headed Ground Beetle features:

Feature	Big Headed Ground Beetle
Color	Black or dark brown
Size	1/2 inch to 1 inch
Legs	Long and strong
Antennae	Elongated and prominent
Mandibles	Well-developed and powerful
Distinguishing	Enlarged, flattened head; tooth-like projections on thorax

Overall, remember to look for the specific coloration, size, anatomy, and distinguishing features when identifying Big Headed Ground Beetles.

Habitat and Distribution

Natural Habitats

Big Headed Ground Beetles can be found in various natural habitats. They thrive in environments such as:

Soil: These beetles live and lay their eggs in the soil, especially in organic-rich or damp areas¹.
Forests: They can be found under logs, rocks, or leaf litter in wooded areas².
Fields: Big Headed Ground Beetles can also be found in grassy fields and meadows, where they hunt for prey³.

North America Geographic Range

In North America, Big Headed Ground Beetles are widely distributed across various regions. They can be spotted in:

Grasslands: These beetles are common in prairie ecosystems, especially in the Midwestern United States⁴.
Gardens: They may be observed in gardens, helping to keep the population of other garden pests in check⁵.
Shorelines: Some species inhabit coastal areas, where they live in sand dunes and along the shoreline⁶.

Habitat	Examples
Soil	Organic-rich or damp areas, forest floors
Forests	Under logs, rocks, or leaf litter
Fields	Grassy meadows, farmland
Grasslands	Prairie ecosystems in the Midwest
Gardens	Residential or urban gardens
Shorelines	Coastal areas, sand dunes

Behavior and Habits

Nocturnal Activities

Big Headed Ground Beetles are primarily nocturnal creatures. They are most active at night, searching for prey like insects and other small invertebrates. During nighttime hunts, they rely on their keen senses to locate and devour their prey.

Hiding and Shelter

During the day, these beetles prefer to hide in various shelters. They can often be found under rocks, logs, and leaf litter to avoid predators and sunlight. These shelters provide sufficient cover and a cool environment for them to rest.

Seasonal Patterns

Big Headed Ground Beetles have different habits depending on the season:

Spring: With increased insect activity, the beetles are often more active and frequently hunt for prey.
Summer: They may become less active due to hot temperatures; however, they still continue their nocturnal foraging.
Fall: As the temperatures drop, they prepare for the coming winter by seeking out well-protected hiding spots.

Some examples of their behavior and habits include:

Ambushing prey at night near their hiding spots
Quickly darting under cover when disturbed in daylight
Communicating with each other using unique body movements

Comparison Table

Attribute	Big Headed Ground Beetle	Other Ground Beetles
Nocturnal	Yes	Most, but not all
Activity Periods	Spring, Summer, Fall	Spring, Summer, Fall
Shelter Preferences	Rocks, logs, leaf litter	Varies, but similar
Main Prey	Insects and invertebrates	Insects and invertebrates

To summarize the section, Big Headed Ground Beetles exhibit nocturnal behavior, prefer hiding during the day, and demonstrate seasonal activity patterns with a preference for spring, summer, and fall.

Life Cycle and Reproduction

Eggs and Larvae

The life cycle of the Big Headed Ground Beetle begins with eggs. Female beetles lay their eggs in soil or among leaf litter. Some characteristics of beetle eggs include:

Small size
Oval or round shape
White or light-colored

Upon hatching, the larval stage begins. Beetle larvae, also known as grubs, possess features like:

Soft-bodied
Cream-colored
Segmented, elongated form

Pupa and Metamorphosis

After the larvae consume enough food and reach the appropriate size, they enter the pupa stage. During this stage, the larvae undergo metamorphosis, transforming into adult beetles. Here are some aspects of the pupa stage:

Protective outer shell
Inactive period for the beetle
Lasts for several weeks

Adult Beetles

Once the metamorphosis is complete, the adult Big Headed Ground Beetle emerges from the pupal case. Key features of adult beetles include:

Hard, protective exoskeleton
Large head and strong mandibles
Dark or iridescent coloration

Adult beetles are not only vital for reproduction but also act as natural predators, controlling insect pests.

Diet and Predatory Nature

Prey Preferences

Big-headed ground beetles are known for their opportunistic feeding habits. Some of the common prey they target include:

Insects
Slugs
Aphids
Snails
Ants
Worms
Caterpillars
Maggots

Occasionally, these beetles might consume seeds as part of their diet.

Feeding Habits

Big-headed ground beetles are mostly nocturnal predators. They actively hunt for their prey at night when the chances of detection are low. During the day, they hide under rocks, logs, or in the soil.

Their hunting strategy often involves ambushing or stalking their prey. They use their powerful mandibles to grasp and crush their prey.

Below is a comparison table of their prey preferences:

Prey Type	Commonality	Vulnerability
Insects	Common	Tend to be easily caught by the beetle
Slugs	Uncommon	Could be difficult for the beetle to capture
Aphids	Common	Vulnerable due to their lack of significant defenses
Snails	Uncommon	Considered a challenging prey due to their shells
Ants	Common	Can be hunted despite their cooperative defenses
Worms	Common	Soft-bodied and easy to catch
Caterpillars	Common	Very susceptible to predation by the beetle
Maggots	Common	Usually an easy target for the beetle

In conclusion, the big-headed ground beetle is a versatile predator that feeds on a variety of small invertebrates. Its nocturnal behavior, combined with effective hunting strategies, ensures its success in maintaining a diverse diet.

Benefits and Impact on Environment

Agriculture and Gardens

Big Headed Ground Beetles can be highly beneficial for agriculture and gardens. A few of their benefits include:

Feeding on pests: These beetles help control harmful insects like wireworms and grubs.
Reducing the need for pesticides: By serving as natural pest control, they decrease the need for chemical pesticides.

Natural Pest Control

Big Headed Ground Beetles are excellent natural pest control agents. Here are some examples of pests they target:

Wireworms: The beetles feed on these pests, which can damage crops by feeding on grass and plant roots.
Grubs: Grubs can be harmful to lawns and gardens. The beetles eat these pests, aiding in maintaining a healthy environment.

Comparison Table

Benefits of Big Headed Ground Beetles	Drawbacks
Natural control of wireworms & grubs	May be sensitive to pesticides
Reducing the need for chemical pesticides	Limited impact on some pests
Safe for beneficial insects & humans	Potential seasonal restrictions

By including Big Headed Ground Beetles in an integrated pest management strategy, both agriculture and gardens can experience significant benefits while minimizing chemical use and supporting a healthy ecosystem.

Interaction with Humans and Homes

Finding Ground Beetles in Buildings

Ground beetles, like the Pedunculate Ground Beetle, can be found in homes and buildings seeking shelter. They are typically identified by their mandibles and iridescent appearance. Often seen near:

Basements
Cracks in foundations
Entry points

Harmful or Harmless?

Ground beetles are generally harmless to people, although some species, like Elistes, can pinch if provoked. However, they can be a nuisance and may damage:

Clothing
Debris
Weeds

Harmful	Harmless
Pinching	Iridescent appearance
Damage to clothing	Do not bite or sting
Nuisance indoors	Beneficial predators in gardens

Preventive Measures

To prevent ground beetles and get rid of them in homes or buildings, follow these steps:

Repair cracks in the foundation
Seal entry points
Use proper lighting to limit attraction
Clear debris and mulch around buildings
Regularly vacuum indoor areas
Keep living spaces clean and clutter-free

Keeping ground beetles away from homes is not only necessary for peace of mind but also to maintain a clean and organized living environment. Stay vigilant and follow preventive measures to keep these critters outside where they belong, and not inside with you and your family.

Ground Beetle Species Diversity

Carabidae Family Overview

Ground beetles belong to the family Carabidae, one of the largest and most diverse beetle families. There are over 40,000 species of ground beetles worldwide, inhabiting various habitats such as forests, fields, and gardens.

Many ground beetles are known for their vibrant, iridescent colors, ranging from shimmering greens and blues to brilliant reds. They have a distinctive appearance, with a hardened outer wing cover (elytron) protecting the delicate inner wings. Some ground beetles are considered beneficial to gardeners and naturalists, as they help control pests by preying on insects such as aphids and slugs.

Notable Ground Beetle Species

Pedunculate Ground Beetle: This beetle species is recognizable by its elongated body and fine puncture marks on its elytron. They prefer open, sandy spaces and can often be found near shrubs or other low-growing plants.
Strawberry Seed Beetle: As its name suggests, this tiny beetle feeds on the seeds of strawberries and other plants. They are small enough to crawl into tight openings and are considered a pest in some agricultural settings due to their feeding habits.

Comparison of notable ground beetle species:

Species	Appearance	Habitat	Diet
Pedunculate Ground Beetle	Elongated body, fine punctures on elytron	Open, sandy areas	Insects
Strawberry Seed Beetle	Small, dark-colored	Gardens, fields	Seeds of plants, especially strawberries

In conclusion, the fascinating diversity of ground beetles in the Carabidae family holds great interest for both entomologists and naturalists alike, offering a glimpse into the complex world of these remarkable insects.

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 – Big Headed Ground Beetle

Vicious pincher?
Location: South-Central Pennsylvania
May 25, 2011 8:43 pm
I’ve been finding about one of these a day in my basement bedroom. This beastly-looking thing was captured and tossed back outside in the grass, where I’d rather they stay. I’m not too keen on being pinched or bitten.
I’ve tried ID’ing it through your site, but there are so many different species of beetle, I don’t know where to begin! I live in south-central Pennsylvania. It’s about half an inch long or so, with an obviously large head, tiny thorax and large abdomen. Can they fly? I would assume this is a PA native?
Signature: Dutch Country Girl

Dear Dutch Country Girl,
This is a Ground Beetle in the genus Scarites. It is most likely Scarites subterraneus, commonly called and aptly named the Big Headed Ground Beetle. You may read more about it on BugGuide where you will find that it is native to your area as well as to much of the continental U.S.

Letter 2 – Big Headed Ground Beetle

Subject: What’s this bug
Location: USA Midwest
November 10, 2015 8:43 pm
My daughter (8yrs old) and I found this bug we live in the midwest near St Louis and the date is November 10th 2015 the weather has been in the mid sixties and we are just curious as to what this bug is? It is about one and a half inches long and about a half inch across any information would be appreciated.
Thanks
Signature: Darla

Dear Darla,
This interesting beetle is a Big Headed Ground Beetle, Scarites subterraneus, and you can confirm our identification by matching your individual to this image from BugGuide. According to BugGuide, they are generally found: “Under stones, leaf litter, etc., in soil.”

Letter 3 – Big Headed Ground Beetle, we believe, from Australia

Subject: Black Ground Beetle?
Location: Victoria, Australia
January 9, 2014 6:44 am
I found this black beetle flying against my window tonight (a warm summer’s night, around 20 degrees C), and am unsure what it is. It looks like a member of Scarites, but I didn’t think they lived in Australia, and I couldn’t find anything about their ability to fly (this was capable of flying roughly two metres off the ground and maintaining that height for several seconds). If it helps, it seemed to be attracted to light.
Thank you in advance for your time.
Signature: –Natasha

Hi Natasha,
We are very intrigued with your request. Your information is very thorough and your photo is excellent. The research you have done already is commendable. First, this is a Ground Beetle, and it is black, but it is most definitely NOT the Black Ground Beetle pictured on the Brisbane Insect website, which is noticeably low on examples from the family Carabidae. We actually agree that this appears to be a Big Headed Ground Beetle in the genus Scarites, and as you have indicated, it is not a genus that is native to Australia. The similarity to that genus is obvious when you compare your photo to this image on BugGuide. According to this online PDF we found from The Coleopterists’ Bulletin entitled Observations on Behavior in Scarites by Thomas F. Hlavac which was published in 1967: “The genus Scarites Fabricius contains a large number of species of large, fossorial, pedunculate beetles and is found in all geographic regions, except the Australian.” With so much global travel in the last fifty years, that may have changed and Scarites might have been introduced to Australia. This FlickR posting would support that possibility. We have not had any luck finding any information on Scarites being able to fly, but we are very curious about that possibility and we thank you for supplying that observation. Of Ground Beetles in general Squidoo observes: “Although some species can fly, they seldom do. In most species the wings have totally disappeared and the wing cases have grown together to form one strong shield.” We will continue to try to research the flying ability of Scarites.

Thank you very much for your fast response! I really appreciate the information, and love your website. Hope you continue the amazing work into futurity!

Letter 4 – Big Headed Ground Beetle and Scarab Beetle Grub

Stupid Question?
Location: southern indiana
September 11, 2011 10:52 pm
Is this grub worm the larva of this pinching bug? It seemed to be guarding all 5 grub worms with it’s life .Just curious thank you
Signature: brian

scarites_brian — Big Headed Ground Beetle

Hi Brian,
The beetle is a Big Headed Ground Beetle, Scarites subterraneus, or another member of the genus. Interestingly, BugGuide has no photos of the Grubs from this genus. Most Ground Beetles have active larvae that are also predators. The Grub image that you submitted looks more like the larva of a Scarab Beetle. Even more interesting is that this is the second letter we have received (the first was earlier this year in May) indicating some reason the Big Headed Ground Beetles are found in close proximity to Scarab Grubs. We are going to try to get Eric Eaton to comment on this.

Letter 5 – Big Headed Ground Beetle

Subject: What the heck is this?
Location: Long Island, NY
May 25, 2012 10:07 pm
This is the second of these guys I have seen in my basement. It made so much noise climbing through some files I thought it was a rat. Even lifted a plastic cup and got out of it. Has pinchers in the front and this one is prob about an inch long give or take a bit.
Signature: Daniel

big_headed_ground_beetle_daniel — Big Headed Ground Beetle

Hi Daniel,
This is one of the Ground Beetles in the genus Scarites, probably Scarites subterranus, the Big Headed Ground Beetle. According to BugGuide, the Big Headed Ground Beetle has a “Distinctive body form and huge jaws, elytra deeply striated.” Like other Ground Beetles, they are predatory and considered beneficial.

Letter 6 – Big Headed Ground Beetle

Subject: Scary Looking Bug
Geographic location of the bug: Long Island, NY
Date: 07/04/2018
Time: 12:50 PM EDT
Your letter to the bugman: Hello, I’ve seen a few of these in our basement. Any idea what it is? Looks like it can bite…
Thank you!
How you want your letter signed: Grifftuh

Dear Grifftuh,
This is a harmless Ground Beetle in the genus Scarites. Though the common name of Scarites subterraneus, according to BugGuide, is Big Headed Ground Beetle, the name could apply to the entire genus.

That’s great. Thank you Daniel. I appreciate you getting back to me!
-Mike

Letter 7 – Big Headed Ground Beetle

Subject: Bug found in London, on, canada
Location: London, ontario, canada
June 3, 2017 9:33 am
Hi, I found this bug crawling across my basement floor yesterday. We live just outside of london, ontario, Canada. Its springtime and it has been hot recently. This bug is close to an inch in length I would say.
Signature: Curtis

Dear Curtis,
We are pretty certain this is a Big Headed Ground Beetle, Scarites subterraneus, but if we are wrong, it is a relative in the same genus. You can verify our identification by comparing your image to images posted to BugGuide. Ground Beetles are beneficial predators that pose no threat to humans. We are post-dating your submission to go live to our site later in the month when our editorial staff is away from the office on holiday.

Letter 8 – Big Headed Ground Beetle and Scarab Grubs

Grubs and beetle
Location: Washington, DC
May 1, 2011 3:15 pm
I found numerous grubs and a few beetles nearby in my vegetable garden today. I wonder if they are related. Any assistance in identifying them would be appreciated.
Signature: Roy

scarites_scarab_grubs_roy — Big Headed Ground Beetle and Scarab Grubs

Hi Roy,
Your grubs and beetle are only distantly related in that they are in the same insect order. The grubs are Scarab Grubs, most likely June Beetles, and they feed on plant roots. The Beetle is a beneficial predator, a Ground Beetle in the genus Scarites. BugGuide lists six species in the genus, and our money is on the Big Headed Ground Beetle, Scarites subterraneus, as the species. You may read about the Big Headed Ground Beetle on BugGuide.

scarites_scarab_grubs_roy_cu — Big Headed Ground Beetle

Letter 9 – Big Headed Ground Beetle

Subject: What’s this bug??
Location: West Central Ohio
May 24, 2015 9:51 am
I find these every year in our pool filter basket (there were 5 in it this AM) West Central Ohio, May through summer.
They are about 1″ long, dark brown, almost black. Is this anything that would be coming from the lawn or be hurtful to the turf? It seems that I see more of them within a week of the Fertilizer man spraying the lawn, but they seem to be attracted to water. I don’t see them in the house, or in the lawn, just in the pool filter basket. ??? Can you tell me what this is? The photos were taken on a white paper towel for maximum contrast. I have looked on the internet, but can’t find anything exactly like this.
Signature: Judy W.

Dear Judy,
This is a Big Headed Ground Beetle in the genus Scarites, and it is a beneficial predatory species that according to BugGuide are: “nocturnal predators on other insects.” Perhaps they are falling in the pool filter while hunting, though we suspect you have a healthy population to be finding so many casualties.

Letter 10 – Big Headed Ground Beetle

Subject: Beetle with segmented body
Location: Southeasten Michigan
June 3, 2014 12:32 pm
hello – love your site. Please help ID this beetle – my wife found in basement – she is freaking out.
Thanks in advance.
Signature: Greg G

Hi Greg,
Calm you wife down and tell her this is a Big Headed Ground Beetle in the genus Scarites, and it is a harmless species that is considered beneficial since it is a predator.

Letter 11 – Big Headed Ground Beetle

Subject: black stag beetle?
Location: mid Missouri
March 25, 2016 5:54 pm
Mr. Bugman,
I found the insect in the pictures on the floor of my kitchen this evening. From the research I’ve done, I am leaning towards some variety of stag beetle. Most of the descriptions I’ve found include black as a possible stag beetle color, but the only pictures I’ve found are for those with giant mandibles like the UK variants.
I’m hoping you can confirm it’s an innocent but misplaced stag beetle that wandered inside, and not some vicious, infectious pest, as my bug-a-phobic mind always assumes.
Signature: Elizabeth

Dear Elizabeth,
Though it resembles a Stag Beetle, this is actually a Big Headed Ground Beetle, Scarites subterraneus, or another member of the genus. This is a beneficial, predatory species and it will not cause any problems for your home or its inhabitants. You can find additional information on BugGuide where it states: “adults are nocturnal predators on other insects.”

Letter 12 – Big Headed Ground Beetle

Subject: Should I be worried
Location: Southern Ontario
May 18, 2016 6:35 pm
Found this bettle with pincers in my house in southern Ontario today. Please help me identify.
Signature: Help pls.

This is a predatory Big Headed Ground Beetle in the genus Scarites, and it is perfectly harmless. It will not hurt you or damage your home. Your individual appears to be covered in dust as this species is generally a shiny black color.

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.