Ground beetles are fascinating insects that can be found in various habitats such as under rocks, logs, and leaves. They are known for their quick movements and ability to help control pests by feeding on their larvae.
These beetles, belonging to the family Carabidae, are often dark-colored and mostly nocturnal. When they feel threatened, many of them run rapidly to find shelter. Interestingly, while these insects have wings, they rarely fly.
Some species of ground beetles emit a strong-smelling irritant when handled, which is another reason they rely on speed rather than flight for self-defense. Overall, their behavior and habits make them a unique type of beetle that’s not dependent on flying for their day-to-day activities.
Ground Beetles Overview
Classification and Species
Ground beetles belong to the family Carabidae and are a part of the larger order Coleoptera. They are prevalent in agricultural and garden settings, playing a crucial role as predators. There are at least 34,000 species worldwide, with hundreds of species residing in the Midwest.
Physical Features
Ground beetles exhibit varying physical features across their diverse species. However, some common characteristics include:
- Size: Ranging from 1/8 to 1/2 inches long, with some reaching 1 inch
- Color: Predominantly black or brown, with some being iridescent and showcasing different colors at various angles of light
- Body parts: Flattened bodies with distinguishable mandibles (jaws) and long, slender legs for quick movement
Their body structures often consist of rows of punctures or grooves down their wing covers, called elytra. Ground beetles also possess antennae for sensory purposes.
Comparison of Features:
| Feature | Ground Beetle | Other Beetles |
|---|---|---|
| Size | 1/8 to 1/2 inches (some up to 1 inch) | Vary significantly based on species |
| Color | Predominantly black or brown; some iridescent or multicolored | Diverse coloration depending on species |
| Wings | Elytra (hardened wing covers) | May have elytra or soft wings, depending on species |
| Legs | Long and slender, facilitating fast movement | Length and structure vary depending on species |
| Distinct Jaws | Mandibles clearly visible on most ground beetles | Jaws may be more or less prominent depending on species |
Keep in mind that these generalizations may not apply to every individual ground beetle species.
Behavior and Habitat
Diet and Feeding Habits
Ground beetles are mostly predatory, consuming a wide range of food types. They are known to feed on:
- Aphids
- Slugs
- Snails
- Gypsy moth
- June bugs
Some ground beetle species are phytophagous or omnivorous, indicating a more diverse diet.
Predators and Prey
Ground beetles have various predators, including birds, small mammals, and other insects such as:
- Lightning bugs
- Ladybugs
Their main prey consists of smaller insects and pests commonly found in gardens and agricultural areas.
Comparison between predatory and phytophagous ground beetles:
| Aspect | Predatory Ground Beetles | Phytophagous Ground Beetles |
|---|---|---|
| Diet | Insects and pests | Insects, pests, and plants |
| Prevalent prey | Aphids, slugs, snails | Aphids, slugs, snails, seeds, and roots |
| Habitat | Gardens, fields | Gardens, fields, and forests |
Ground beetles typically hide during the day and are found on the ground under leaves, logs, stones, loose bark, and in grassy areas. They are active at night and may sometimes be attracted to lights. When exposed, they move quickly to find shelter but rarely fly.
In summary, ground beetles are a diverse group of insects with varying diets and habitats. They serve as both predators and prey in their ecosystems, and their presence can be beneficial in controlling pests in gardens and agricultural settings.
Reproduction and Life Cycle
Egg and Larva
Ground beetles go through a process called complete metamorphosis, beginning with the egg stage. Female beetles lay eggs in different environments depending on the species, often in soil or decomposing organic material1. These eggs typically hatch within 7 to 10 days into larvae2.
Larvae are the second stage in the ground beetle life cycle, and they are also known as insect larvae or maggots3. They have voracious appetites and will feed on other insects, helping to control pests in gardens and agricultural systems4.
Pupa and Adult
After the larval stage, ground beetles transform into pupae. During the pupal stage, the larvae undergo metamorphosis, in which they transform into adult beetles5.
Once the transformation is complete, adult ground beetles emerge from the pupal stage, ready to mate and continue the life cycle6. Many adult ground beetles live in similar environments as larvae, often hiding under rocks, leaves, or logs during the day and becoming active at night7.
Ground Beetle Life Cycle Features:
- Complete metamorphosis
- Egg, larva, pupa, and adult stages
- Eggs often laid in soil or decomposing material
- Larvae are voracious predators
- Pupae undergo transformation to become adults
- Adults often active at night
Notable Ground Beetle Species
Calosoma Beetles
Calosoma beetles are known to be colorful and fast-moving. They consume a wide variety of prey, which includes caterpillars and aphids. A key feature of Calosoma beetles is their ability to fly, allowing them to hunt more effectively.
Some characteristics of Calosoma beetles include:
- Vibrant metallic colors
- Wings for flying
- Voracious predators
Bombardier Beetles
Bombardier beetles are another fascinating ground beetle species. They are known for their unique defense mechanism which involves spraying a hot, noxious chemical mixture at potential predators. This defensive secretion is produced by combining hydrogen peroxide and hydroquinones, stored in separate abdominal chambers, and released through an opening at the beetle’s rear end.
Here’s a comparison of Calosoma and Bombardier beetles:
| Feature | Calosoma Beetles | Bombardier Beetles |
|---|---|---|
| Colors | Vibrant metallic | Mostly brown or black |
| Wings | Yes (can fly) | No (flightless) |
| Predation | Caterpillars, aphids | Not applicable |
| Defense Mechanisms | None mentioned | Hot chemical spray, defensive hairs |
For example, the African bombardier beetle (Stenaptinus insignis) can spray its defensive secretion at a temperature of around 100°C, and travel at a speed of around 20 km/h!
In conclusion, Calosoma and Bombardier beetles are interesting ground beetle species with unique traits, such as Calosoma’s flying ability and Bombardier’s chemical defense mechanism. They serve as examples of the remarkable diversity found within the ground beetle family.
Ground Beetle Identification and Control
Identifying Ground Beetles
Ground beetles are typically small to moderate-sized insects, ranging from 1/8 – 1/2 inches in length, while some can even reach up to 1 inch 1. They have certain features that help in identification:
- Flattened body
- Obvious mandibles (jaws)
- Iridescent coloring, usually black or brown
Carpet beetles are different from ground beetles in appearance, usually being round-shaped with varying patterns on their body and having hair-like bristles on their back2.
Natural Control Methods
There are several natural methods to help control ground beetle populations:
- Encouraging natural predators like birds and frogs
- Installing barriers such as copper tape or crushed eggshells
- Keeping gardens clean and free of debris
- Reducing outdoor lighting, as it attracts beetles
Treatment and Removal
In case of a ground beetle infestation, consider the following treatment options:
- Using insecticides, granules, or sprays to target beetles directly
- Applying diatomaceous earth around beetle entry points
- Placing sticky traps inside the house, near potential entry points
However, these treatments may have certain drawbacks:
- Insecticides can be harmful to other beneficial insects and pets
- Diatomaceous earth may need frequent reapplication
- Sticky traps may catch non-target organisms
Benefits of Ground Beetles
Ground beetles are beneficial insects for many reasons. They play a crucial role as predators in garden and agricultural ecosystems. Let’s take a look at some of their benefits:
- Natural pest control: Ground beetles help in controlling pests by feeding on harmful insects’ larvae, such as slugs, caterpillars, and aphids 1.
- Low maintenance: These beetles are self-sufficient, requiring no additional care or resources from humans 2.
To help you better understand the benefits of ground beetles, let’s compare them to chemical pest control methods:
| Feature | Ground Beetles | Chemical Pest Control |
|---|---|---|
| Eco-friendly | Yes | No |
| Harmful to beneficial insects | No | Yes |
| Cost-effective | Yes | No |
| Long-term effectiveness | Yes | No |
Ground beetles are a science-supported method of pest control. They provide a more sustainable and eco-friendly solution compared to chemical alternatives, showcasing their usefulness in maintaining overall ecological balance.
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 – Pedunculate Ground Beetle
Subject: Large Black smooth beetle
Geographic location of the bug: Oklahoma City
Date: 08/27/2018
Time: 11:54 AM EDT
Your letter to the bugman: I am 41 and first time I have ever seen this beetle. Was not able to locate a match for Oklahoma or Texas. Was about an inch long. Looked like very strong pinchers and was trying to come in front door. It is mid August late morning
How you want your letter signed: Very curious
Dear Very curious,
This is a Pedunculate Ground Beetle in the genus Pasimachus, and according to BugGuide: “Large, extra-robust, flightless ground beetles (elytra fused into rigid shell). Huge jaws, head, pronotum. Some have blue margins. Typically run about under or on leaf litter in forests.” They are beneficial predators that are harmless to humans.
Letter 2 – Long Necked Ground Beetle
Hello Again ! Can You Help?
Thu, Oct 23, 2008 at 10:39 AM
I found this beetle walking along the wall around my porch lights. I discovered it in the spring at night time, where all sorts of insects appear! It is one of the weirdest beetles I have ever seen. (note the thorax). I’ve had quite a lot identified on your website, and hope you can continue to help the poor, helpless public. Thanks!
Luke
Murrayville, Georgia
Hi Luke,
This is a Long Necked Ground Beetle, Colliuris pensylvanica. According to BugGuide, it is found : “In leaf litter and under logs and stones, and on vegetation in wet areas”
Letter 3 – Mite on Ground Beetle
Subject: Bugs on bugs.
Geographic location of the bug: Vernon, British Columbia, Canada
Date: 10/30/2017
Time: 12:39 PM EDT
Upon taking some photographs of a Granulated Carabid, I noticed that there was a smaller individual on the subject. Locating several other Carabids in the area, it was found that several individuals had these unknown hitchhikers, with numbers ranging between 0 and 4.
How you want your letter signed: Scott
Dear Scott,
The creature you found on this Granulated Carabid is a Mite, and there are phoretic or hitchhiking mites that use beetles as a means of transportation. Phoretic Mites are commonly found on Sexton Beetles in great numbers and the Mites take advantage of the flying Sexton Beetles to transport them to new locations to find food. We know of no instances of phoretic Mites using Ground Beetles for transportation, so it is entirely possible that this particular Mite might have a more ominous reason for being on the Granulated Carabid you found. Ground Beetle Macro Photography has an example of a Mite found on a Ground Beetle but there is no explanation. This might be a phoretic Mite, but we haven’t the expertise with Mites to be certain.
Letter 4 – Ground Beetle
What’s this bug?
Dear WTB,
My brother and I spotted this beautiful beetle near Munson Falls, on the Oregon Coast. We are wondering what kind it is? Thanks,
Sarah Kanz
Hi Sarah,
Your beetle is a Ground Beetle, Scaphinotus angusticollis. We identified it on BugGuide.
Letter 5 – Granulated Ground Beetle
A further identification for you
Hey there! Love the site. I noticed on your main page that Cheryl from British Columbia sent you images of lace bugs and a mystery ground beetle. Her beetle looks remarkably to me like a specimen I snapped a shot of last week on the other side of the country, just north of Toronto, Ontario. I think her mystery beetle is Carabus granulatus, an introduced species from Europe. Here’s a link to my picture as posted on bugguide.net: http://bugguide.net/node/view/109257
Dave Kleiman Thornhill, Ontario, Canada
Hi Dave,
Thanks for the correction and also thank you for providing an image of a living specimen of the Granulated Ground Beetle.
Letter 6 – Ground Beetle
Beetle in Basement
Thu, Oct 16, 2008 at 6:10 PM
I am finding these beetles in my house. What are they? While I have found one on the main floor, most are appearing in my finished basement playroom. The living ones I have found seem to be trying to burrow in the carpet. In our utility room (unfinished basement space) I have found several carcases that spiders seem to have killed. Can you identify this bug from the attached image? Do I need to be concerned about finding these in my kids playroom?
Long Island, NY
Dear Long Island, NY,
This is a Ground Beetle in the genus Scarites. It will not harm you, your children, or your home. This Ground Beetle is a nocturnal predator that feeds on other insects. You can read more about them on BugGuide.
Letter 7 – Fierce Ground Beetle
Subject: Black Beetle in Texas
Location: Texas
June 17, 2016 6:35 am
I saw this beetle in April 2011 in Texas in Kickapoo State Park. It was 2-3 inches long, a big beetle.
What is it?
Signature: Joe
Dear Joe,
We were able to identify quickly this Fierce Ground Beetle in the genus Pasimachus on BugGuide. According to BugGuide, Fierce Ground Beetles eat “caterpillars, other larval insects.” Based on your location, we believe you have either Pasicachus californicus which according to BugGuide, their range is: “AZ-TX-NE-UT / Mex. (does not occur in CA)” or Pasimachus depressus which according to BugGuide is “Noted from Carolinas, Oklahoma. Internet references suggest it is found west to Arizona” and described as “Large, black, elytra and pronotum often bordered with blue/violet. Elytra of male shiny, of female dull, neither have striations or punctures. Base of pronotum (next to abdomen margined). Hind tarsus long and slender.”
Thanks Daniel!
It was the biggest beetle I ever saw in the us that wasn’t in captivity.
Joe Greco
Letter 8 – Ground Beetle
Subject: Eleodes?
Geographic location of the bug: Thornton Colorado 80241
Date: 08/05/2018
Time: 02:26 PM EDT
Your letter to the bugman: Found a lot of these guys running around a school. Followed by a lot a questions about what it is.
How you want your letter signed: Thank you for your help!
This is definitely not a Desert Stink Beetle in the genus Eleodes. It is a beneficial, predatory Ground Beetle in the family Carabidae. Here is a similar looking individual pictured, but not identified, on BugGuide.
This was the first page I found that finally solidified my ID of Pasimachus depressus, so I thought I’d share the video I took of one at my farm in De Leon Springs brutalizing a grub. Enjoy!
https://www.instagram.com/p/BIqLSM-AAWX/?taken-by=lawblick
Hopefully, someone will notice this.
I have recently caught some small carabids for captivity, and there were similar-looking ones walking on the ground and sitting on them. An earwig was also found running around with a cluster on its back. I am under the impression that parasitic mites move very little and stay near their feeding spots, though I could be wrong. The ones I observed seemed to have antenniform front legs, suggesting that they are highly mobile.
That no instances of phoretic mites were known to you on ground beetles is not much of a surprise, since the “bug” world is largely undocumented.
Hopefully, someone will notice this.
I have recently caught some small carabids for captivity, and there were similar-looking ones walking on the ground and sitting on them. An earwig was also found running around with a cluster on its back. I am under the impression that parasitic mites move very little and stay near their feeding spots, though I could be wrong. The ones I observed seemed to have antenniform front legs, suggesting that they are highly mobile.
That no instances of phoretic mites were known to you on ground beetles is not much of a surprise, since the “bug” world is largely undocumented.
Also called Blue Margined Beetle (Pasimachus depressus), I found one recently in Winter Park area of Orlando, FL. Can have blue outline on its exoskeleton under the right angle of sunlight.