What Do Darkling Beetles Eat: A Quick Guide for the Curious

Darkling beetles are fascinating creatures found in various habitats all over the world. You might have come across them in your garden or even during an evening stroll. These beetles are usually black or brown and can be quite intriguing to observe. Curious about what they eat? Let’s explore their diet and uncover some interesting facts about these little critters.

Primarily, darkling beetles are known to feed on plant foliage. They can chew on seedlings and damage several vegetable crops, such as figs ^(source). These beetles prefer to be active at night but may also be found running on the ground during the day, often hiding in clods or debris to escape the heat.

Their feeding habits make these beetles a concern for gardeners and farmers alike, but remember that not all of them are harmful. Some species even play a vital role as decomposers and recyclers in their ecosystems. So, if you encounter darkling beetles, take a moment to observe their fascinating behavior and appreciate their unique characteristics.

Understanding Darkling Beetles and their Classification

Darkling beetles belong to the family Tenebrionidae that is part of the large order of insects called Coleoptera. Just like other beetles, these insects exhibit some distinctive features, which will be briefly discussed in this section.

You might recognize darkling beetles by their dull black or brown color, as well as their slow movement. They are mostly scavengers and feed on a variety of sources. For example, they are known to chew off seedlings or feed on foliage of different vegetable crops and fruit crops.

When it comes to the size, darkling beetles are typically small to medium-sized insects. Many species within this family possess wingless bodies. Here are some characteristics to help you identify them:

• Dark color (black or brown)
• Slow-moving
• Small to medium-sized
• Often wingless

There are around 1,200 species of darkling beetles found in North America, with most of them concentrated in the western region. An interesting example in the Tenebrionidae family is the Namib desert beetle, which is known for its ability to collect water from fog using its unique elytra structure.

In conclusion, darkling beetles are a diverse group of insects that can be found in various habitats and are known for their scavenging behavior. By understanding their classification and basic features, you can now identify these insects with ease and observe their unique role in the ecosystem.

Physical Traits and Adaptations of Darkling Beetles

Darkling beetles are known for their distinctive black or brown coloration, which may help them blend into their surroundings. Their flightless nature is a result of fused elytra that form a shield-like structure over their abdomen. This protects the beetle from predators and harsh environments.

You’ll notice darkling beetles have segmented antennae, which they use for sensing their environment. These sensory organs are crucial in locating food and identifying potential mates. Their eyes exhibit unique adaptations to suiting their nocturnal lifestyle. Here are some of their standout features:

• Fused elytra for protection
• Segmented antennae for sensing
• Well-adapted eyes for low-light environments

Another interesting aspect of their anatomy is the abdominal sternite – a plate on the underside of their abdomen. This protects their soft underbelly and contributes to their overall hardy nature. Their frontal ridge, or the raised portion between their eyes, is a distinguishing characteristic that sets them apart from other beetles.

Darkling beetles possess unique tarsi, or foot segments, on their legs. These specialized structures provide grip and stability when they move across various surfaces. You can also notice their mid legs, which assist in digging and burrowing.

As you can see, the darkling beetle’s physical traits and adaptations make it well suited for thriving in its natural habitat.

Habitats of Darkling Beetles

Darkling beetles are highly adaptable and can be found in various environments across the globe. In North America, for instance, these beetles thrive in diverse habitats such as deserts, forests, and grasslands. There are about 1,200 species of darkling beetles in North America, primarily in the West.

These beetles are also prevalent in other parts of the world, including Africa, where they have adapted to different climates and ecosystems. In deserts, you can find darkling beetles scurrying on hot sand during the day, while they take refuge under rocks and debris to avoid the extreme temperature.

In contrast, forest-dwelling darkling beetles seek moist and cooler areas, often hiding under logs or leaf litter. These insects are highly dependent on surrounding vegetation to regulate their body temperature. Additionally, they require moisture to survive and can be found in areas with some form of humidity.

To summarize, darkling beetles can be found in various habitats such as:

• Deserts
• Forests
• Grasslands

Overall, darkling beetles are highly adaptive insects that can thrive in different environmental conditions. These creatures play an important role in their habitats as scavengers, feeding on various materials such as decaying plant matter, fungi, and even some fruit crops like figs.

Life Cycle and Biology of Darkling Beetles

The life cycle of darkling beetles can be broken down into four main stages which include eggs, larvae, pupae, and adults. Let’s take a quick look at this complete metamorphosis:

• Eggs: The beetles lay their eggs, which typically hatch within 7 to 10 days.

• Larvae: Once hatched, the darkling beetles are in their larval stage, often referred to as “mealworms.” During this time, they grow and molt, undergoing several larval stages.

• Pupae: After the last larval stage, the larvae become pupae. In this inactive stage, they undergo significant transformation.

• Adults: When pupation is complete, the adult darkling beetles emerge, ready to reproduce and continue the cycle.

It’s fascinating to see how different the biology of darkling beetles is from that of humans. Unlike humans, they don’t grow gradually but rather experience immense transformations during their life. In each of these stages, their diet and behaviors vary, allowing them to adapt to specific environmental conditions and needs.

For example, the larvae or mealworms are known to feed on grains and other stored food products. In contrast, adult darkling beetles switch their diet to vegetarian, consuming plant-based materials. This diverse diet contributes to their vast distribution and high adaptability, making them a common sight in various habitats.

Dietary Preferences of Darkling Beetles

Darkling beetles have varied dietary preferences, ranging from plant material to organic matter. As scavengers, they contribute to breaking down organic waste in nature.

These beetles consume a variety of elements. Some examples of their diet include:

• Mealworms: The larvae of darkling beetles, commonly known as mealworms, feed on grains, seeds, and cereal. They can be found in flour and grain storage areas.
• Fungi: Both adult and larval darkling beetles enjoy feeding on fungi, which contributes to breaking down decomposing organic matter.
• Dead Insects: Darkling beetles scavenge dead insects as part of their protein intake.
• Water: As all living organisms need water, darkling beetles, too, require it for survival. They obtain water from their food and also from other moist sources.
• Plants and Vegetation: These beetles feed on various plants and plant materials. For instance, they chew off seedlings or feed on foliage of different vegetable and fruit crops, such as figs.

Darkling beetles play an essential role in the ecosystem by consuming waste or decaying matter. To recap, their diet mainly consists of:

• Mealworms (grains, seeds, cereal)
• Fungi
• Dead insects
• Water
• Plants and vegetation

The diet of darkling beetles allows them to thrive and carry out their role as decomposers in the ecosystem. Remember to be conscious of their presence in food storage areas, as they may lead to contamination.

Darkling Beetles as Scavengers and Decomposers

Darkling beetles are known to be effective scavengers and decomposers in their ecosystem. They primarily consume dead plant and animal materials, significantly contributing to the decomposition process.

These creatures exhibit a preference for rotting wood and decaying plant tissues. Besides, they are also found munching on dung and other organic matter. By breaking down these materials, they enrich the soil with essential nutrients, thus supporting the growth of plants.

For example, some darkling beetle species can be found on rotting logs, while others might prefer leaf litter and decomposing foliage. Their nocturnal nature means they are most active at night, foraging and feeding on the available resources.

Their role as decomposers sustains the natural cycle of life. By breaking down dead materials, these creatures pave the way for new life to flourish in the environment.

While darkling beetles pose no severe harm to a healthy ecosystem, they can occasionally damage agricultural crops. They have been known to feed on vegetable foliage at night, impacting the growth and yield of plants in some cases.

It’s important to note their contributions to the ecosystem far outweigh any downsides they pose, making darkling beetles crucial to the health of the environment.

In conclusion, as scavengers and decomposers, darkling beetles play an essential role in breaking down dead plant and animal material. They help in recycling nutrients within the ecosystem, providing for the healthy growth of new life. However, their occasional love for agricultural crops should not be ignored.

Roles of Darkling Beetles in the Ecosystem

Darkling beetles are essential players in their ecosystem. They help break down dead plant material and play a crucial role in nutrient cycling. For instance, they feed on dead plants (detritus) but will also eat fresh plants.

These beetles are considered omnivores because they can also feed on several vegetable crops and fruit plants, such as figs. The fact that they are most active at night adds to their importance in maintaining a balanced ecosystem.

As nocturnal creatures, darkling beetles serve as a primary food source for a diverse range of predators:

• Birds
• Reptiles
• Rodents
• Bugs

Remember that these beetles are not just prey for other animals, but also have their place in controlling other insect populations. By feeding on decomposing organic matter, darkling beetles help keep their environment clean and healthy.

To summarize, here’s how darkling beetles contribute to their ecosystem:

• Decompose dead plant material
• Control other insect populations
• Serve as a food source for various predators

So as you can see, darkling beetles play a significant role in maintaining a balanced ecosystem, ensuring ongoing biodiversity and stability in their environment.

Darkling Beetles as Pests

Darkling beetles can become pests in various situations, especially when it comes to grain storage and storage facilities. They are known to cause infestations in stored grains, resulting in significant damage to these products. These beetles are not only a nuisance but can also lead to economic losses.

For example, in the agricultural sector, darkling beetles feed on the foliage of several vegetable crops and sometimes on fruits like figs (source). They can chew off seedlings which hinder crop growth. During the daytime, they often hide under debris and become active at night.

These beetles are similar to flour beetles, another type of stored product pest. Both of them infest stored grains, but darkling beetles are more likely to be found in grain storage with inadequate sanitation measures. When they infiltrate storage facilities, they contaminate the stored grains and even consume them which ultimately leads to reduced product quality and potential economic losses.

Below is a comparison table highlighting the similarities and differences between darkling beetles and flour beetles:

In conclusion, to prevent infestations and minimize the damage caused by darkling beetles, it is important to maintain proper sanitation in storage facilities, monitor the presence of these pests, and implement an effective pest management plan. By doing so, you can protect your stored grains and other valuable commodities from the harm caused by darkling beetles.

Darkling Beetles and Human Interactions

Darkling beetles have some interactions with humans, pets, and poultry farms. These beetles are not known to transmit diseases like salmonella, but they might carry pathogens.

As nocturnal scavengers, darkling beetles occasionally find their way into homes. They feed on dead material, like clothing or rugs, as well as rotting wood and fungi source. However, they don’t tend to bother humans or pets directly.

In poultry farms, darkling beetles can become a nuisance. They may:

• Populate chicken coops, feeding on poultry feed and droppings.
• Hide in dark and damp areas, like the corners of a container or under feeders.
• Attract predators, such as rodents and wild birds, which might carry diseases.

Regarding feeder insects, darkling beetles can serve as a food source for some animals – for example, reptiles and amphibians. In this context, they play a role in the pet industry, providing a source of nutrition for captive animals.

Overall, darkling beetles have a limited impact on humans. They are a part of the ecosystem but generally don’t present significant issues.

Darkling Beetles in Different Geographies

Darkling beetles are known for their widespread distribution across various geographic regions, including Latin America, Australia, and other continents. Due to their diverse habitats, these beetles experience variations in their feeding habits.

In Latin America, for example, darkling beetles mainly scavenge on decaying plant materials. They especially thrive in warm, tropical climates where decomposition occurs at a faster rate. These beetles play an essential role in the ecosystem, contributing to the natural recycling of nutrients.

Meanwhile, in Australia, darkling beetles can be found inhabiting various environments such as forests, grasslands, and deserts. As a result, their diet consists of a wider range of organic materials. In some cases, darkling beetles in Australia have been observed feeding on the foliage of several vegetable crops and even fruit crops like figs.

When examining their feeding habits across different geographies, it’s important to note that darkling beetles are primarily nocturnal creatures. Their nighttime foraging allows them to consume a variety of dead materials like rotting wood, fungi, and other organic matter.

Overall, darkling beetles are versatile creatures with diverse feeding habits across different geographic locations. Their adaptability is a testimony to their significance in maintaining ecological balance within various ecosystems around the world.

Interesting Species of Darkling Beetles

The world of darkling beetles is vast and varied, with over 20,000 species in the family Tenebrionidae. A few particularly interesting species include Eleodes, Bolitotherus, and those that take the forms of wireworms.

Eleodes are known as desert darkling beetles, and they thrive in arid environments. They primarily feed on decaying plant matter and are known for their distinct defensive behavior. When threatened, Eleodes stand on their head and release a foul-smelling substance to repel predators¹.

Another fascinating species is the forked fungus beetle (Bolitotherus cornutus), which is unique as the only member of its genus². These beetles are found in Missouri and play an essential role as decomposers, feeding on fungi and decaying wood.

Darkling beetles that take the form of wireworms are the larval stage of certain species in the Tenebrionidae family. These larvae can be agricultural pests, causing damage to crops by feeding on seeds, seedlings, and roots of various plants³.

In summary, these interesting species of darkling beetles showcase the diversity within the Tenebrionidae family:

• Eleodes: Desert darkling beetles

  • Thrive in arid environments
  • Feed on decaying plant matter
  • Known for their unique defense mechanism

• Forked fungus beetle (Bolitotherus cornutus)

  • Only member of its genus
  • Found in Missouri
  • Feed on fungi and decaying wood

• Wireworms (larvae form)

  • Agricultural pests
  • Damage crops by feeding on seeds, seedlings, and roots

As you explore the world of darkling beetles, remember that there are many intriguing species, each with unique characteristics, contributing to the ecosystem in which they reside.

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 – Stink Beetle

Large SoCal Ground-Dwelling Beetle
Howdy Bugman 🙂
Recently we’ve had a visitor hanging out on our patio at night in Bonsall, CA. It’s what I think might be a Darkling or ‘Acrobat’ beetle… it doesn’t fly, is pretty huge and often walks with his ‘butt’ up in the air… amusing actually…. here’s a good pic…. thought maybe you could confirm my suspicion. thanks,
mark

Hi Mark,
Darkling Beetle and Acrobat Beetle are two common names for beetles in the genus Eleodes, also commonly called Stink Beetles.

Hi, Daniel:
The “Eleodes” recently posted from California might be in the genus Coelocnemis instead. I can’t tell positively from this image alone, but the large thorax suggests Coelocnemis. They mimic Eleodes in behavior, but are more common than Eleodes in pine forest habitats. Just want to say, essentially, that genus identification is probably impossible from just one image.
Eric

Letter 2 – Acrobat Beetle

Subject: Black beetle in Santa Fe does a fearsome handstand
Location: Santa Fe, New Mexico
May 18, 2013 12:45 pm
I found this beetle, which was about the size of my thumb, outside my dormitory. When I poked it, it did a little handstand and stuck out its hind legs, presumably to dissuade me from eating it. I wasn’t actually hungry, but I was intimidated all the same.
Signature: Mendez

Dear Mendez,
We love your photo of an Acrobat Beetle or Desert Stink Beetle in the genus Eleodes.  When disturbed, the Acrobat Beetle sticks its butt up in the air and releases a foul odor to dissuade predators.  We often see Desert Stink Beetles in Los Angeles parks and open spaces and at Joshua Tree National Park.  You can browse BugGuide to try to identify your Acrobat Beetle to the species level based on the appearance of its fused elytra or wing covers and your location in New Mexico. 

Letter 3 – Stink Beetle

Colorado Springs Beetle
This came crawling along the floor in the basement of our Colorado Springs, CO home. We brought it outside, but it promtply died on our icy deck. While collecting it for transport, it emitted a chemical smell. The smell is quite potent. Is it of the genus Eloedes? Darkling beetle? Thanks for the info.
ryan

Hi Ryan,
You are correct. Darkling Beetles in the genus Eleodes are sometimes known as Stink Beetles.

Letter 4 – Superworm Beetle

Subject:  What kind of beetle is this?
Geographic location of the bug:  Spring, Texas
Date: 09/11/2017
Time: 08:29 AM EDT
Found this guy upstairs in our house. Wondering what it is? Want to release him back into the wild. Should I be worried there are more in my house?
How you want your letter signed:  Krissi

Dear Krissi,
We are pretty confident telling you this Beetle will not harm your home nor its occupants, though we are having a difficult time identifying it.  Though it resembles a beneficial, predatory Ground Beetle, the antennae seem entirely too serrated to be a member of that family.  The antennae remind us most of a Longhorn Beetle in the family Cerambycidae, but we don’t believe that is correct either.  We suspect this is a Darkling Beetle in the family Tenebrionidae, but we have not been able to identify the genus nor species.  We are going to contact Arthur Evans and Eric Eaton to seek assistance.

Hi again Krissi,
Does anyone in your home have a pet that requires worms from the pet store?  See Arthur Evans identification below.

Arthur Evans identifies the Superworm Beetle
It looks like this to me: http://bugguide.net/node/view/132236

Eric Eaton Concurs
I would agree with Art.
Eric
author, Kaufman Field Guide to Insects of North America
http://bugeric.blogspot.com/

Letter 5 – Wooly Darkling Beetle

What’s this beetle?
Location: Los Angeles, CA
March 12, 2011 9:18 pm
Hi!
See these guys on my walks in the hills all the time. Slow movers, maybe 1-2 cm in length.
Located in Montecito Heights, Los Angeles.
(not too far from you 🙂
Thanks!
Signature: Aaron

Hi Aaron,
This critter is a Wooly Darkling Beetle, Eleodes osculans, one of the desert Stink Beetles.  They are often found ambling about in vacant lots and other open areas.  The erect red hairs that cover the body are a distinguishing feature of the Wooly Darkling Beetle.  You can see BugGuide for additional information.

Hi Daniel,
Thank you very much! I had incorrectly identified this guy as belonging to the Trichiasida genus, but I see he is definitely a Eleodes osculans!
These have been a common sight ambling along the hills around here, it’s nice to know who I’m walking with!
Many thanks
Aaron

Letter 6 – Desert Stink Beetle

Nevada WCTA Insect Survey
Location: Red Rock Canyon National Conservation Area, Las Vegas, NV
April 18, 2012 4:32 pm
I think this is an Eleodes, but I would like confirmation.
Signature: Alayna

Hi Alayna,
We agree that this is a Desert Stink Beetle or Acrobat Beetle in the genus Eleodes, and it looks very similar to this individual from Utah posted to BugGuide that is not identified to the species level.  BugGuide also notes that there are over 129 species in North America that are “Divided into 14 subgenera based primarily on female genitalia.”  We do not have the necessary skills to make a species identification.  Desert Stink Beetles are often found ambling slowly over the terrain.  If they are disturbed, they lower their heads, raise their abdomens and emit an odor, hence the two common names.  We especially like the name Acrobat Beetle.

Letter 7 – Secretions from an Acrobat Beetle

Pinacate Beetle Secretions
November 10, 2011 11:14 pm
Do you know of anyone who has had the secretions from this beetle on their skin? What does it look like?  I suspect my daughter has been repeatedly sprayed by this beetle that was in her shoe, and she has a dark black area on 2 toes that will not wash off.
Signature: Lori Lindley

Dear Lori,
Since you did not attach a photo, we located a recent image from our archives of a Pinacate Beetle in the genus Eleodes, also called an Acrobat Beetle or Desert Stink Beetle.  We have no knowledge that the malodorous secretion produced a chemical stain on skin, so we did some research.   According to the Exploring the Southwest Desert USA website:  “They are well known for their comical, yet effective, defense tactics. When alarmed they stand on their heads by bending their front legs down and extending their rear legs. Depending upon the species, they exude an oily, musty secretion, which collects at the tip of the abdomen or spreads over posterior parts of the body, or they eject the reddish brown to brown secretion as a spray. Larger desert species, like E. armata and E. longicollis, can spray 10 to 20 inches. Most species can spray multiple times, if necessary. The spray is not painful unless you get it in your eyes or mouth, where it is painful, burning and temporarily blinding. It does not wash off.”

Letter 8 – Stink Beetle

Three Bugs from near Sedona, AZ
I was trying to find out what type of beetle we came across on our last trip to the Oak Creek area of Sedona in June of 2003, when I found your way cool site. This photo was taken near the part of Oak Creek where so many of the pretty pictures of Cathedral Rock are taken. I think this might be a type of ground beetle. It was about two inches long — when threatened, it put its head down while tipping its rear end up. If you can identify any of these, I’d be grateful.
Su — Mesa, AZ

Hi Su,
Let’s start with the Beetle. This is a member of the Family of Darkling Beetles, Tenebrionidae, genus Eleodes which are known as Stink Beetles. According to Hogue they are “smooth shiny black beetles. … They are medium to large (1 to 1 1/4 in.) and their wing covers are fused along the midline making it impossible for them to fly. These conspicuous beetles are usually encountered as they amble along the ground. Individuals may also be found under stones and loose tree bark, where the long cylindrical larvae also live. … When a Stink Beetle is disturbed or its wandering is interrupted, it stand on its head and points it rear end into the air. For thi headstanding habit, these insects are sometimes called ‘Acrobat Beetles.’ Adults may emit a disagreeable though weak odor when handled.”

Letter 9 – Acrobat Beetle

Identify Beetle
Location: Baja California – near Tecate
November 1, 2011 1:57 pm
A friend of mine is in Baja California — wondering what this bug is.
Signature: Reubin

Hi Reubin,
Stink Beetles in the genus Eleodes are frequently called Acrobat Beetles because they strike this pose and release a foul odor when threatened.

Letter 10 – Acrobat Beetle in Griffith Park

Subject: Near Griffith Observatory
Location: Los Angeles
April 15, 2013 9:01 am
My son’s cub scout pack is interested in this beetle. Can you please identify? we found it on a path as we were hiking to Griffith Observatory in LA in 4-14-13. We were near Hollywood, CA.
Thanks,
Signature: Dan Y

Dear Dan Y,
This is a Desert Stink Beetle in the genus Eleodes, and they are commonly called Acrobat Beetles since they point their bottoms up in the air when threatened.  We used to see them quite frequently while hiking near the Observatory, back in the 90’s when the editorial staff of What’s That Bug? worked as the photography staff in the dome under the solar telescope.

Letter 11 – Black and White Acrobat Beetle

Subject:  Black and White Darling Beetle?
Geographic location of the bug:  Corona, CA
Date: 03/17/2019
Time: 08:45 PM EDT
Your letter to the bugman:  I can’t find any information on white Darkling beetles.  This beetle does the classic tail in the air when threatened pose.
How you want your letter signed:  JohnD

Dear JohnD,
The piebald markings on your Acrobat Beetle or Stink Beetle in the Eleodes, a genus well represented on BugGuide, do not seem naturally occurring to us.  Also, the markings appear to be layered, with a whiter coloration on top of a creamier coloration.  Is it possible this Acrobat Beetle had an encounter with a paint brush?  We will continue to research this matter.

Hi Daniel,
We thought that same thing at first.  However, we were not able to carefully scrape off any of the white and cream color like we would have been able to if it were paint.  Additionally, we found him quite far from houses in a river bed/ravine location. Unfortunately for us, but fortunately for the bug, we have a standing order for our 9 year old to safely release all bugs after taking a short look at them.  We will look around near where he released it to see if we can find it again and get to the bottom of the mystery.
Thanks!

Letter 12 – Desert Stink Beetle

Subject: black beetle
Location: stanford university hills, northern california
March 24, 2014 4:53 pm
it bugs me that i do not know the identity of this common bug
BTW – it likes mushrooms
Thanks
Signature: virusmanbob

Dear virusmanbob,
This is a Desert Stink Beetle in the genus Eleodes.  They are sometimes called Acrobat Beetles because of the way they position themselves when threatened, with head lowered and rear end up in the air.  You can view additional images on BugGuide.

Dear Daniel –
This is awesome!  Thank you so much!
This is my first query to whatsthatbug and it works!
On my website, I posted your reply with attribution and a link to whatsthatbug:
http://www.stanford.edu/~siegelr/insects/eleodes.html
I am a frequent mushroom observer user and I am hooked on that as well.
Best, Bob

Letter 13 – Desert Stink Beetle

Subject: Beetle
Location: Sun Valley, CA
May 17, 2016 7:24 pm
Started seeing a lot of these guys walking around.
Signature: Don’t care

This is a Desert Stink Beetle or Acrobat Beetle, a group of distinctive black Darkling Beetles that often stand still with the tip of the abdomen pointed up while expelling a foul odor, a survival strategy that explains both common names.  BugGuide also indicates Circus Beetle is name that describes the entire genus.  Your individual has a set of characteristics:  smooth elytra, pointed abdomen tip and broad pronotum, that is quite distinctive.  The closest match we could find on BugGuide is  Eleodes acuticaudus.

Letter 14 – Desert Stink Beetle

Subject:  Desert Stink Beetle
Geographic location of the bug:  Joshua Tree National Park, California
Date: 04/04/2019
Time: 11:15 AM PDT
No trip to the desert would be complete without an encounter with a Desert Stink Beetle or Acrobat Beetle.

Letter 15 – Desert Stink Beetles

Subject:  Black beetles
Geographic location of the bug:  Denver City , Texas
Date: 06/16/2019
Time: 08:10 PM EDT
Your letter to the bugman:  Hello!!! We have had an explosion of these beetles. Never seen them here before.
How you want your letter signed:  Bugs aren’t scary

These appear to be Desert Stink Beetles in the genus Eleodes, possibly Eleodes fusiformis which is pictured on BugGuide.  Desert Stink Beetles are sometimes called Acrobat Beetles or Circus Beetles because they have a habit of sticking their abdomens in the air when threatened, and they appear to be standing on their heads.  The group image you submitted appears to document mating activity.

Letter 16 – Tok-Tokkies or Darkling Beetles from Namibia

Subject: Coleoptera in Namibia
Location: Namibia
February 1, 2015 4:11 am
This insect was in the namib desert in Namibia :
https://goo.gl/maps/2OQMc
Would it be called the tok tokkie beetle ? What is the scientific name ?
Signature:  A Traveler

Dear A Traveler,
According to Beetles in the Bush:  “‘Tok-tokkie’ refers not to a particular genus or tribe of tenebrionids, but rather a number of flightless species that have developed a unique “tapping” method of communication between males and females.  The name “tok-tokkie” is onomatopoeic, referring to the sound these beetles make when they tap their abdomen on the ground.  In the same way that fireflies have species-specific patterns of flashes, different species of tok-tokkies tap with differing frequencies.  The beetle makes the noise by raising its abdomen and then bringing it down on the surface of the ground several times in quick succession.  Males initiate the tapping and await a response from a receptive female.  Signals are exchanged back and forth until, eventually, the two locate each other and mate.  Females lay eggs in shallow excavations in the dry, sandy soil, and the larvae that hatch feed within the soil on the roots of small plants.”  Your individual is a Darkling Beetle in the family Tenebrionidae, so the name Tok-Tokkie is appropriate.  We cannot say for certain the exact species.

Two other images you submitted are also flightless Tenebrionids, so they can also be called Tok-Tokkies.

Subject: Coleoptera in Namibia
Location: Namibia
February 1, 2015 4:14 am
This insect was in the namib desert in Namibia :
https://goo.gl/maps/2OQMc
Thanks for your research !

Letter 17 – Unknown Darkling Beetle from Belize

Subject:  Interesting Tenebrionid that needs an ID…
Geographic location of the bug:  Belize, Central America
Date: 12/16/2017
Time: 11:36 PM EDT
Hi bugman! In August 2017, we collected this beautiful Tenebrionid in Central Belize in the Northern Maya Mountains. Elevation at this site is about 700-ft and it is primarily Tropical Broadleaf Forest. I thought I would put it up on your site to see if anyone may have an ID for it or at least some direction we could go for an ID. And yes, we did have a collecting permit from Belize plus a 3-177 from the U.S. Fish and Wildlife Service for the collections. Thank you very much.
How you want your letter signed:  David Wyatt

Dear David,
We are posting your Darkling Beetle image as requested.  This is sure a brightly colored Darkling Beetle.  We hope you are able to eventually get a correct identification.

Letter 18 – Unknown Larviform Creature from Australia may be Darkling Beetle Larvae

Subject: Black Larvae?
Location: Logan Village, Queensland, Australia
December 7, 2013 6:11 pm
Hi, I found these coming and going from a large crack in a concrete slab. They’re about 1.5 cm long and have a light green belly. Hoping you can identify them.
Signature: Snap

Dear Snap,
We have no idea what these creatures are.  They might be beetle larvae, and then again, they may be more primitive insects or arthropods.  We will continue to research this matter and perhaps one of our readers (AussiTrev are you out there???) might be able to assist in this identification.
P.S.  When you stated “these coming and going” did you find more?  How many?  A colony?

Eric Eaton provides his opinion
Hi:
I’d say it is probably a chrysomelid leaf beetle larva, but I’m not that great with Australian insects.
Eric

Hi Daniel, thanks for you quick reply.
The first time I saw them, earlier this year I think, there were probably a total of 100 or more. Sighted over a few days, coming out of the same crack in the concert slab. I was ‘removing’ them once or twice a day.
This time there was only about 30 and they seemed to be heading to the crack…from where, I could not determine. Perhaps they’d been out for the day and were returning home 😉 They definitely seem to be a colony, but where they’re based, I presume under the slab?, I can’t see.
Thanks so much for your help and hope to hear from you very soon.
Regards
Nina

Thanks Nina,
We are still working on this.  Here is what Eric Eaton has to say, but the fact that they appear to be a colony associated with a slab of concrete is not consistent with what we would expect from Leaf Beetle Larvae.

Update
Thanks Daniel
I may have been mistaken about the crack in the concrete. I’ve just taken another look and there are some loose bricks right next to the crack, and it appears they are coming/going from under or behind them. Please see attached. One photo is of the debris under the brick. I’m sure it’s not all a result of these larvae, but there does appear to be dead ones in amongst it, along with other insect bits and pieces. The second photo is of 2 approaching the crack and loose bricks.
Would it make sense that Leaf Beetle larvae would opt to make use of such an area?
Cheers
Nina

Thanks for the update Nina.  Though we still don’t have an answer for you, we are happy about some new clues.  We do not believe these are Leaf Beetle Larvae and we believe Eric Eaton might agree with the new photos.  The debris under the brick might hold clues regarding the anatomy of the adult beetles.  Those appear to be brown beetle elytra or wing covers in the dirt.

We have made several other requests from knowledgeable folks who contribute to our site and we hope to eventually have an answer for you.

Update:  Possibly Carrion Beetle Larva
Hi again Nina,
We are obsessed with this identification.  The closest visual match that makes sense is a Carrion Beetle Larva.  Carrion Beetles lay eggs on dead animals and the larvae feed on the putrefying flesh and the maggots that are attracted to the decomposition.  Your beetles resemble this image of Carrion Beetle Larvae from our archives.  We continued to dig and found this image of a Carrion Beetle Larva, Eusipha japonica, which is probably a Japanese species, on FlickR.  The Calodema Supplementary Paper No. 79 (2008) mentions a species Ptomaphila perlata.  We tried to find a photo of that larva and we found a drawing that looks very similar on Beetle Larvae of the World.  We then found a photo on Alum Cliffs, Dec 2009 that looks very close to your larva, but you must scroll down the page to view it.

A Different Opinion
December 9, 2013 4:16 am
Hi,
here another opinion. In my eyes this maybe the larva of a tenebrionid beetle, subfamily Lagriinae.
I found several pictures in the internet which are rather close. For instance here:
http://www.rbgsyd.nsw.gov.au/science/Evolutionary_Ecology_Research/Ecology_of_Cumberland_Plain_Woodland/woodland_wildlife/invertebrate_animals/ecnolagria_grandis
I could, owever, not find a picture that matches 100%.
larva of Lagriinae is, however, only a possibility, I am not sure…
Erwin
Signature: Erwin Beyer

Thanks Erwin,
We also thought Darkling Beetles might be a possibility, but we couldn’t locate any matching larval images.  Thanks for supplying a link.

Hi Daniel
It does look very similar to Carrion beetle larva Ptomaphila lacrymosa (Silphidae), except for the side pieces? where the legs are attached, which are more pronounced (larger and flatter) in your example.
The brick: Please note, that this brick has holes in it, which allows many insects to climb in/out and die in and under it. It hasn’t been moved in about 15 years or so. Therefore, it is probably a bit of a bug cemetery. I just turned over another larva and it wasn’t as lime green on the belly, as the one in my photo, more cream in colour.
There only appears to be a few crawling around now, so their obvious activity appears to only last a few days. I wish I could provide more information. Perhaps I should preserve one or two somehow?

More questions from Nina
Hi Daniel
Yes, the tenebrionid beetle larvae is VERY close! This is image is the closest I have found http://beetlesinthebush.wordpress.com/2011/02/14/answers-to-id-challenge-5-artropodes-em-casca-de-arvore-morta/
The fact that they live off and on dead trees? is a bit disconcerting, if they’re heading for my house. Although, I’m a tad paranoid after having battled termites for nearly 2 years.
If they’re in the larvae stage, I may seem an influx of a particular beetle soon? Being ignorant to the cycles of insects, how long would the larvae stage last?
thanks
Nina

Hi again Nina,
The link you provided does look very close.  We don’t believe you need to worry about these larvae infesting your home.  Most larvae live less than a year before metamorphosing into adults, but some may live several years in the immature stages.  We are uncertain how long the larval stage of this creature will last.

Thanks for your efforts Daniel. I’m happy with the conclusion that it’s some type of beetle larvae. No doubt this will not be the last time I submit a bug for identification. We live on 5 acres of bushland, so there’s an abundant supply!
Enjoy your festive season and have a merry Christmas!
Cheers
Nina

Letter 19 – Woolly Darkling Beetle

Subject: What’s this beetle
Location: North East Los Angeles
February 15, 2017 11:21 pm
Found this beetle on the floor of our house in the Montecito Heights area of Los Angeles. Can you let us know what it is?
Signature: Thanks,

Greetings from Mount Washington, right across the Arroyo Parkway from you.  We recognized your beetle as a member of the Darkling Beetle family Tenebrionidae, so we turned to Charles Hogue’s “Insects of the Los Angeles Basin” and we located your Woolly Darkling Beetle, Cratidus osculans, on page 299 where it states:  “It is often seen in vacant lots and along paths through brushy or wooded areas.”  Based on BugGuide, the genus has been reclassified as Eleodes osculans.

Letter 20 – Soldier Beetle from Peru

Subject: Beetle
Location: Moyobamba area Peru
January 15, 2017 4:07 am
Please could you help ID this beetle we saw at Waqanki Lodge, Moyobamba, Peru – September 2016? Thank you
Signature: Lynne Demaine

Dear Lynne,
We wish we could make out the detail on the antennae better as that is a big help in classification.  We are pretty certain this is NOT a Longicorn in the family Cerambycidae, we also believe we can eliminate it being a Darkling Beetle in the family Tenebrionidae.  We are pursuing research that this is a member of the superfamily Elateroidea, possibly the Soldier Beetle family Cantharidae.  While there are some similar looking Soldier Beetles pictured on Scielo, we were not able to locate a conclusive match.  Perhaps our readership can assist with this identification.

Thank you Daniel for your quick reply – I will hope someone out there can ID it for me!
I have attached a second photo that I took – it does show one of the antennae slightly better.
Best wishes

Facebook comment from Tina
Plausibly Chauliognathus heros, a type of soldier beetle.
Coleopteres du Panama

Ed. Note:  We also found a matching image on Project Noah of an individual from Costa Rica.