Do Giant Mesquite Bugs Bite? Dispelling Myths and Uncovering Facts

Giant mesquite bugs are large, impressive insects that are often found in areas with mesquite trees. These bugs, belonging to the family Coreidae, are known for their striking appearance and the crucial role they play in the ecosystem. However, many people wonder if these fascinating creatures have a downside, like the potential to bite humans.

Although their needle-like mouthparts might appear intimidating, the good news is that giant mesquite bugs are herbivores and primarily feed on mesquite tree sap. Their mouthparts are adapted for piercing and sucking plant fluids, not for biting humans or animals. This means you can appreciate their presence without worrying about being bitten.

Despite their harmless nature, it is essential to understand the broader context of mesquite bugs and their relationship with their environment. They serve as essential pollinators, crucial for the survival and growth of mesquite trees. So, while they do not pose a threat to humans through their bites, they do play a vital role in maintaining the ecosystem of regions where they reside.

What Are Giant Mesquite Bugs

Thasus Neocalifornicus

Giant mesquite bugs, scientifically known as Thasus neocalifornicus, are large insects native to the southwestern United States and Mexico. They belong to the insect family Coreidae, commonly referred to as leaf-footed bugs, and are known for their striking appearance.

Insect Family Coreidae

Coreidae is a family of insects containing over 2,000 species, and they bear a characteristic leaf-like structure on their hind legs. These insects, including the giant mesquite bugs, typically feed on plant sap and are not known to bite humans. Here are some features of giant mesquite bugs:

• Large body size: they can measure up to 1.6 inches in length
• Striking coloration: Black and red markings on their wings and bodies
• Leaf-like structures: Found on their hind legs

Sonoran Desert Habitat

Giant mesquite bugs mainly inhabit the Sonoran Desert, which covers parts of the southwestern United States and Mexico. In this ecosystem, they are commonly found on mesquite trees, their primary food source. These bugs play a role in their environment by feeding on and assisting in controlling the population of mesquite trees.

In conclusion, giant mesquite bugs, or Thasus neocalifornicus, are large, visually striking insects belonging to the Coreidae family. They inhabit the Sonoran Desert and feed on the sap of mesquite trees. While they may appear intimidating, they are harmless and do not bite humans.

Biology and Life Cycle

Nymph Stages

Giant mesquite bugs are known for their distinctive nymph stages. They go through five different instars, each with unique color patterns and morphological features:

• 1st instar: Bright red with black markings and black legs
• 2nd instar: Red-orange with black markings and black legs
• 3rd instar: Red-orange, more black markings and wing pads start developing
• 4th instar: Reddish-brown, wing pads growing, and yellow spots appear
• 5th instar: Dark brown, with wing pads almost fully developed, yellow spots turn into distinctive bands

Univoltine Life Cycle

Giant mesquite bugs exhibit a univoltine life cycle, meaning they produce one generation per year. Adults usually emerge during early spring, mate, and lay eggs on mesquite trees. The eggs hatch into nymphs, which feed on the mesquite plant and undergo several molting stages.

Lifespan

The total lifespan of these insects is still not well-studied, but the univoltine nature of their life cycle suggests a relatively short lifespan for individual bugs. Adult giant mesquite bugs typically die shortly after mating and egg-laying, while the nymphs that hatch from these eggs will become the next generation of adults.

Here’s a comparison table for the life stages of giant mesquite bugs:

Some notable features of giant mesquite bugs are:

• Attractive color patterns, especially in nymph stages
• Their unique ability to feed on mesquite trees
• A univoltine life cycle with one generation per year

Giant Mesquite Bugs and Mesquite Trees

Diet and Nutrition

Giant mesquite bugs, also known as large milkweed bugs, are insects that primarily feed on mesquite trees. Their diet mainly consists of:

• Mesquite tree seeds
• Young shoots
• Leaves

These bugs extract the nutrients they require from these tree parts. Nevertheless, giant mesquite bugs do not bite humans, as they aren’t harmful to people.

Nectar Consumption

Although mesquite bugs predominantly depend on their host tree for nutrition, they also consume nectar occasionally. Nectar provides them with an additional energy source. However, their nectar consumption does not negatively impact mesquite trees.

Do Giant Mesquite Bugs Bite Humans

Stingers Vs Proboscis

Giant mesquite bugs and mosquitoes have different mouthparts, affecting their ability to bite:

• Giant mesquite bugs have a proboscis, which is a long and thin feeding tube primarily used for sucking plant sap.
• Mosquitoes have a needle-like proboscis, allowing them to puncture human skin and extract blood.

As a result, giant mesquite bugs do not bite humans, while mosquitoes do.

Pallid Bat Predators

• Giant mesquite bugs serve as food for pallid bats, a species known for hunting insects.
• Pallid bats primarily feed on insects with more substantial exoskeletons, such as scorpions, crickets, and grasshoppers.
• While the bites of mosquitoes may be itchy and annoying to humans, they pose no threat to pallid bats, who generally do not feed on them.

In summary, giant mesquite bugs and mosquitoes differ in their ability to bite humans due to their mouthpart structure. The giant mesquite bug has a proboscis adapted for sucking plant sap, while the mosquito’s needle-like proboscis is designed for extracting blood from its host. Giant mesquite bugs are part of the pallid bat’s diet, whereas mosquitoes generally do not serve as a primary food source for these predators.

Prevention and Control Measures

Neem Oil Application

Applying neem oil is a great natural solution to prevent and control giant mesquite bugs. It is:

• Environmentally friendly
• Biodegradable
• Derived from neem tree seeds

Dilute neem oil with water and spray it on affected areas. Neem oil tends to be more effective on smaller bugs, so apply it early in their life cycle.

Mesquite Twig Girdler Management

Mesquite twig girdlers are another pest that affects mesquite trees. These pests can be damaging, but there’s a silver lining: they’re not known for attacking healthy trees. Maintain your tree’s health, and you’ll likely keep mesquite twig girdlers at bay. Examine and prune damaged branches to limit their spread.

Tree Borer Control

Tree borers are an additional pest that can infest mesquite trees. They can cause significant damage, making prevention crucial. Here are some methods:

• Keep trees healthy
• Apply insecticides (where appropriate)
• Monitor and inspect trees regularly

Giant Mesquite Bugs Vs Mosquitoes

Similarities and Differences

Giant mesquite bugs and mosquitoes are both insects found in various environments. While not all types of mosquitoes bite humans, those belonging to the Culicidae family are notorious for their bites¹. On the other hand, giant mesquite bugs are mostly plant feeders and do not bite humans. Let’s compare some of their characteristics:

Zika Virus and the CDC

One major difference between mosquitoes and mesquite bugs is their potential to transmit diseases to humans. For example, mosquitoes can transmit the Zika virus, which is a concern for public health. The Centers for Disease Control and Prevention (CDC)² provides guidelines on managing mosquito populations to prevent the spread of diseases.

In summary, although giant mesquite bugs and mosquitoes are both insects, they have distinct differences in their feeding habits, biting tendencies, and associations with disease transmission.

Interesting Facts About Giant Mesquite Bugs

Carbon Dioxide Sensitivity

Giant mesquite bugs, which can be found on mesquite trees during May-August, are known to be sensitive to carbon dioxide. This sensitivity enables them to detect the presence of humans and other animals. For instance:

• They can sense an increase in carbon dioxide levels in their surroundings
• This helps them avoid potential predators

Sweat Attraction

Interestingly, these bugs are attracted to human sweat. The reason behind this attraction lies in the various chemicals present in our sweat, such as:

• Salts
• Organic compounds
• Amino acids

These substances may serve as a potential food source or play a role in their behavior.

Communication through Pheromones

Giant mesquite bugs use pheromones as a means of communication within their species. Some key aspects of their pheromone communication include:

• Attracting mates
• Signaling danger
• Marking territory

Though these bugs may be a common sight on mesquite trees, they cause no significant plant damage, are harmless to humans, and do not have a venomous bite or sting, as mentioned in this source.

Comparison between Giant Mesquite Bugs and other common insects:

In summary, giant mesquite bugs have intriguing abilities and behaviors such as their sensitivity to carbon dioxide, attraction to sweat, and communication through pheromones.

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 – Giant Mesquite Bug from Mexico

Unidentified Hemiptera
Tue, Dec 9, 2008 at 3:58 PM
Hi!
I was hoping you can help me identify this insect. I know it belongs to the true bug or Hemiptera group.
They are abundant in a small area of tall grasses and spiny bushes near Ciudad Guzman, in the Mexican state of Jalisco, within sight of the Zapotlan lake. Although they are most common during the warm season, this one I photographed during winter.
There seem to be several species with different markings on their wings and body. This one is rather dull colored (except for the metallic blue section between the wings, which Im afraid didnt get too well represented in the photos), there are others with bright white, black and orange spots. Some are much bigger than this one.
They usually hide underneath leaves or spiny branches, and if they see you look at them, they move so that they remain hidden. If handled for too long, they shoot a red-orange or brown liquid that smells like a marker and is seemingly absorbed by skin within seconds. I haven´t felt any kind of effect after being shot with this fluid.
They fly, but not often. They seem to be fond of spiny bushes and acacia, but I’ve also found them in pine trees, sometimes in groups. I’ve seen some eaten from the inside by fungi.
I hope this information is useful.
Dragonfly Man
Near Zapotlan lake, Jalisco, Mexico

Dear Dragonfly Man,
This is a Giant Mesquite Bug, Thasus acutangulus. The winged adults are considerably less colorful than the wingless nymphs, which are black, orange and white as you describe. The thorny shrub you describe is probably mesquite, the favored food plant.

Letter 2 – Giant Mesquite Bug

A new bug for me
Hello,
I’m having a hard time identifying a bug and was wondering if you could put a name to a face for me. It is about 2.5 inches long. I couldn’t get a good picture, but instead of jaws it has a ‘snout’, for lack of a better term. Much like a tool it would use to gather nectar… maybe. I’m in Southeastern Arizona right near the border between the Sonoran and Chihuahuan deserts. We are currently in the monsoon season which brings out all sorts of little crawlies. This is just one I’ve never seen before. Thanks.
Mark P

Hi Mark,
Your letter is the second today with images of the Giant Mesquite Bug, Thasus acutangulus.

Letter 3 – Giant Mesquite Bug

Bug??
I searched your website but could not find anything similar to this bug. This bug was sited on the Anza trail between Tumacacori and Tubac along the Sant Cruz River. The trail was littered with these bugs, they were a bright red with white and black markings ranging from the size of a dime to the size of a quarter. The time of day was early morning. A fellow hiker said that he had heard them referred to as Mexican Generals, but I can’t find anything on the internet. Thank you
Patty Giles

Hi Patty,
We have several images of Giant Mesquite Bugs in the genus Thassus on our True Bugs pages. We love the name Mexican General. Your photo is of a nymph. Adults have fully formed wings.

Letter 4 – Giant Mesquite Bug

red mesquite bug
Hi there.
I live in southern Arizona and wonder about this fellow. He’s about an inch and a half long, seems to suck the young peas inside mesquite (velvet variety). Any idea? I run a newspaper, so, I’ll give your website credit with a description if you name him.
Thanks,
Joseph Birkett

Hi Joseph,
This is a Giant Mesquite Bug. About a year ago, we identified it as Thasus neocalifornicus. Bugguide currently has a very similar looking species identified as Thasus acutangulus. We are not certain if these are separate species or if the taxonomy is changing. To add confusion, we have also found internet references with the genus spelled Thassus, probably an error. At any rate, your photo is of an immature specimen. Adults have wings. They feed on juices from mesquite at all stages of development.

Letter 5 – Giant Mesquite Bug

found this beetle on my front porch.
My son and I came home and found this beetle on our front porch. It is roughly an inch long. After checking it out we saw another one hanging around. I cannot find this bug any where on the internet or in books. Please help to identify it. We live in Southeast Tucson, AZ.
Thank you
John

Hi John,
Your visitor is not a beetle. It is an immature Giant Mesquite Bug.

Letter 6 – Giant Mesquite Bug

What is this beautiful bug
Would you be so king as to tell me what bug this is? Thanks you for your time and attention in this matter. Take care,
Suzanne

Hi Suzanne,
This is an adult Giant Mesquite Bug, Thasus acutangulus. We get photos of the even more brightly colored nymphs more often than we get images of the adults.

Letter 7 – Giant Mesquite Bug

Mystery bug found in Tucson AZ
Hi, we’ve been trying to ID this insect on your site for several hours to no avail. We found it yesterday evening crawling across the ground in Tucson, AZ. Thanks!
Connie

Hi Connie,
This is a Giant Mesquite Bug, Thasus acutangulus. We get more requests to identify the colorful nymphs than we do the winged adults.

Letter 8 – Giant Mesquite Bug

giant mesquite bug
Hi, I just have to say I love your website!!! I sent in 2 photos of a colorful ‘beetle’ a few days ago, and have been eagerly awaiting your response. Someone told me the bug I found was a ‘Walapai Tiger’ -which freaked me out because I read it can make you really sick. (and we let it crawl all over our hands!) However, as I only looked on your pages from 2007, I was not able to correctly ID my ‘beetle’. I looked through some of your older pages and found out that my ‘beetle’ was actually a giant mesquite bug. I am much relieved to find out its not dangerous. The pictures I sent had my dog, Layne’s, nose in them and I was more concerned for him than myself. I would like to urge readers to look in your archives as some of these insects emerge seasonally (like the Palo Verde Beetle) and there may be info from years past. Thanks for such a wealth of knowledge and a bunch of nice photos! Kudos!!!
Jen

Thank you so much Jen,
First, we must appologize for not answering you sooner, but people don’t realize how long it takes to do a single posting to our site. You original letter and image was on our back burner, but it seems there has been a backlog on the front burners as well due to summertime being peak insect season. We want to thank you for your praise and suggestions as well as for using our archives since that is the reason they are there. Your point about seasonal occurrances is totally accurate. Many casual visitors to our site do not get past the “Ask WTB?” link when the object of their desire is a scroll down the homepage. We have answered countless requests this month for Cicada Killer identifications despite it being the featured Bug of the Month. In this world of instant gratification, many people have gotten lazy. They also don’t realize that here at What’s That Bug? we are artists, not trained entomologists. We derive all of our responses by doing internet research. We are not getting paid and we do not have the time nor energy to research every blurry photo or vague description that is sent our way. Many a letter just goes directly to the trash icon. Again, we had plans to post your lovely image of an adult Giant Mesquite Bug because most of the images of the species Thasus acutangulus are of immature nymphs with their bold coloration. The wings of the adult hide the colorful patterns on the abdomen.

Letter 9 – Giant Mesquite Bug

stunning bug on Cassia fistula
Dear Bugman,
Can you help me with this one? This beautiful insect is on Cassia fistula, a small, quite common tree in the Guadalajara, Jalisco, Mexico area. Very calm, not easily disturbed by being moved around or photographed, but I haven’t seen it on any other plant except the cassia. Many thanks if you can identify it.

Hi Nancy,
This is a Giant Mesquite Bug nymph, Thasus acutangulus. They nymphs are much more colorful as the adults wings cover the patterned abdomen. Most of our U.S. reports of the Giant Mesquite Bug come from Arizona.

Letter 10 – Giant Mesquite Bug

What’s this bug
Found this bug in the Riviera Maya area in Mexico. Any idea what it is. It is about the size of a kidney bean. Thanks
Nancy

Hi Nancy,
This is a Giant Mesquite Bug nymph, Thasus acutangulus, or a very closely related species.

Letter 11 – Giant Mesquite Bug

A Gorgeous Kooky Striped Bug from Sierra Madre

S/he’s a little early for Halloween, but sporting fancy socks
and ready for any hootenany. This ~2.5′ damsel/fellow lives
on Altavera Street in Guanajuato, Mexico, in the Sierra Madre
mountains. Anyway, we met her in June when the entire city
had flooded and everybody was trapped in their/our houses.
We waded out seeking food and came across this quite jubilant
bug – s/he was cruising pretty fast and being studiously avoided
by all (albeit otherwise traumatized) town inhabitants. Except
us. We did the opposite, came over for a visit with her, and
hoped for the best. What IS she? Many many thanks,
Quintan Wikswo
Los Angeles, CA

Hi Quintan,
What a wonderful description of a Giant Mesquite Bug, Thasus acutangulus.

Letter 12 – Giant Mesquite Bug

Blue, red and white bug, with orange and black legs Fri, Nov 7, 2008 at 5:57 PM
We found this bug while doing some sightseeing in Oaxaca, Mexico. My friend noticed it first, I almost walked right into it! We just had to take a picture of it, though neither of us could tell what it was. The colors are just stunning, and you can see the patterns continue underneath the body too. We thought it almost looks like a beetle or stink bug, but we have no idea. Any help in figuring out what this bug is would be appreciated!
Sightseeing in Mexico
Oaxaca, Mexico

Dear Sightseer,
This is either a Giant Mesquite Bug, Thasus acutangulus, or a closely related species. Your specimen is an immature nymph. Interestingly, we just posted an image of another nymph from Peru that reminds us of this species.

Letter 13 – Giant Mesquite Bug

Central Mexico Beetle
May 21, 2010
This colorful beetle was observed on some rock steps near hot springs in the Guanajuato province of Mexico. There was lots of vegetation around the area along with springs. At first I thought someone had painted this and put it there for a joke, but on closer look, it started to move and walk away. I have yet been unable to identify this guy.
Harvey A.
Guanajuato near San Miguel de Allende

Dear Harvey,
The immature Giant Mesquite Bug in the genus Thasus in your photo will lose its bright coloration upon incomplete metamorphosis into a winged adult.  We are not certain that it is Thasus neocalifornicus, which is found in the American Southwest and Mexico, or Thasus acutangulus, which ranges further south.  We profiled the latter species in an earlier letter.

Letter 14 – Giant Mesquite Bug from Mexico

Found in Mexico, Satelite: Aug 27, 2011
Location: Mexico, Satelite
September 19, 2011 9:31 pm
Can you tell me the name of this bug and what family it belongs to. Also, does this bug have a stinger?
Signature: Rosa Maravillas

Hi Rosa,
This is a Giant Mesquite Bug or a close relative in the genus Thasus.  Giant Mesquite Bugs are in the family Coreidae, the Leaf Footed Bugs or Big Legged Bugs and they do not have stingers.  We frequently get requests to identify the brightly colored nymphs of the Giant Mesquite Bug, and you can see photos of the entire life cycle on Colin L. Miller’s wildlife website.

Letter 15 – Giant Mesquite Bug

Subject: Souther Arizona flying beetle?
Location: Tubac, Arizona
August 25, 2015 8:08 pm
Hey Bugman!
My friend, Tim, is visiting Tubac, Arizona and sent me this.
“so this guy is big, 1 1/4” snout to tail. good flyer, has mouth parts like an assassin bug, and has 1/8” circles 2/3 of the way out on his antennae.
i was thinking kissing bug, but never found a pic of that crazy antenna.”
Thank you!
Signature: Tim via Tomas

Dear Tim vie Tomas,
Thank you for providing such a detailed description of this Giant Mesquite Bug.  The Giant Mesquite Bug does not have the evolutionarily evolved legs of many other members of the Big Legged or Leaf Footed Bug family Coreidae.  Immature nymphs are quite colorful and often congregate until they grow wings and can disperse.  Your detailed description included the enlarged antennae segments of the Giant Mesquite Bug, but alas, you need a faster shutter speed, probably quicker than 1/250, to keep the rapidly moving antennae from blurring.

Letter 16 – Giant Mesquite Bug

Subject: Cricket with wings or a Beetle
Location: Arizona
September 24, 2015 10:11 pm
A friend of mine was traveling in Arizona and she almost stepped on this big 2 inch bug/beetle,
It looks kind of like a big black fly but also looks lie a cricket with wings.
Can you tell me what it is?
Signature: Darlene

Dear Darlene,
Your friend encountered a Giant Mesquite Bug.  Most of the images of this species on our site are of the colorful immature Giant Mesquite Bugs that feed in groups.  The flattened segment on the antennae is quite distinctive, and the powerful legs on your individual indicates it is a male.

Letter 17 – Giant Mesquite Bug from Costa Rica

Subject: Costa Rica Bug ID
Location: Costa Rica – Altitude approx. 2500 feet.
March 18, 2016 5:51 pm
Hi Bugman, My husband found this fellow crawling on our car. We live in the central valley mountains of Costa Rica at altitude approx. 2500 feet. His body was approx. 1″ long and he was a fast mover… not standing still for anyone.. (even a man with a camera). I assume it’s some kind of beetle, but it also seems to have a shield shape like the Stink bugs back in the US. Is it maybe a tropical version of the the stink bug?
Thanks,
Signature: Jackie

Dear Jackie,
We believe this member of the family Coreidae is a Giant Mesquite Bug in the genus Thasus.  We get numerous images of the colorful immature nymphs, and your winged adult resembles this image on FlickR.

Hi Daniel…  Thank you for your quick reply and the identification.
After looking at your links, I would agree with you on your identification…  Although I will pass on the reply that stated they can be used as a food source/flavoring agent.   LOL…  Just not “in to” serving my family bugs for dinner.  😉
Thanks again and have a great Sunday!
Jackie

Letter 18 – Giant Mesquite Bug from Mexico

Subject: Mexican Red Abdomen Winged Beetle
Location: Puebla, Mexico
December 6, 2016 9:06 pm
Hi! I have been searching around using different key words but I don’t have the knowledge to sufficiently describe at least the curious antennae of this winged beetle found in Mexico in the state of Puebla. It would be amazing if either you know the beetle and its genus/latin name, and I would be very Very curious to read your scientific description of the beetle. The language for these descriptions are fascinating (something we take for granted all too often). Whenever possible, I’d love to know more. Thank you in advance and my sincere appreciation for your support!
Signature: Sean Aguirre Buckley

Dear Sean,
There are very few online images of Giant Mesquite Bugs from the genus Thasus online that show the red abdomen, but we did locate this image on BugGuide.  The Giant Mesquite Bug is a True Bug in the family Coreidae, the Big Legged Bugs or Leaf Footed Bugs, not a beetle.  We get numerous requests to identify the colorful nymphs of Giant Mesquite Bugs that tend to feed in groups.