Square Headed Wasp: Quick Facts for the Curious

Square-headed wasps are a fascinating group of insects with unique features and behaviors. These remarkable creatures belong to the subfamily Crabroninae, which hosts a diverse range of 4,700 species, 520 of which can be found in a particular region like the United States source. As their name suggests, they are recognized by their distinct square-shaped head, which sets them apart from other wasps and insects.

These wasps are solitary by nature and are known to construct nests using their impressive jaws. They create homes in a variety of places such as the ground, hollow stems, pith of broken stems, and old galleries source. Although they might appear intimidating, square-headed wasps play a crucial role in the ecosystem as predators of other insects, helping to keep their populations in check.

Stay with us as we reveal more interesting facts about the square-headed wasp, from its life cycle and hunting strategies to its role as a pollinator. You’ll soon be an expert on these extraordinary insects, unlocking an even greater appreciation for nature’s beauty and complexity.

Exploring the Square-Headed Wasp

The square-headed wasp, a member of the subfamily Crabroninae in the Crabronidae family, is a fascinating insect to explore. These wasps belong to the Ectemnius genus and are known for their unique appearance and behavior.

One distinct feature of square-headed wasps is their appearance. They are easily recognized by their square-shaped head and medium size, around ½ inch long. With an unmarked but hairy gray thorax and blue-gray markings on their abdomen, they stand out from other wasps. Adults also have mostly yellow legs, which makes them even more distinguishable from other wasps.

These wasps are not just interesting to look at but also helpful to the ecosystem. Adult square-headed wasps feed on nectar and pollen. They contribute to pollination while feeding, as the pollen sticks to their hairy thorax, allowing them to transport it efficiently.

As a square-headed wasp, you’ll also have some fascinating nesting behaviors. Females of this species progressively provision their nests rather than providing a finite food supply. In doing so, they ensure the continuous growth and development of their offspring.

In summary, square-headed wasps are captivating insects that play a vital role in the ecosystem. By feeding on nectar and pollen, they contribute to pollination and plant growth, essentially helping the environment thrive. Their unique appearance and nesting behaviors make them a fascinating study subject, offering more insight into the diverse world of wasps.

Physical Features

Head and Antennae

The Square Headed Wasp, also known as Ectemnius spp., is named for its unique and impressive head shape. The wasp’s head resembles a small, equilateral square, which is quite distinct from other wasps. Their antennae are relatively longer than those of regular wasps, assisting in detection and communication.

Abdomen and Waist

The abdomen of the Square Headed Wasp features a narrow waist and longitudinal grooves. This characteristic not only gives the wasp its signature appearance but also plays a role in their agility and flexibility.

Legs and Wings

Square Headed Wasps have six legs and two pairs of wings like other wasps, but they exhibit distinct differences:

  • Their legs have adaptations for enhanced climbing and digging.
  • The wings offer better maneuverability for these solitary wasps.

Distinguishing Traits

Here are some key identifying traits of Square Headed Wasps:

  • Square-shaped head: The head is smaller compared to other wasps and has a unique square shape.
  • Impressive jaws: These wasps have powerful jaws, essential for hunting and nest building.
  • Special grooves: Longitudinal grooves in the abdomen provide flexibility and distinction from other wasps.

In conclusion, the physical features of Square Headed Wasps make them easy to identify, agile, and equipped for their solitary lifestyle. Paying attention to their head shape, antennae, abdomen, legs, and wings will help distinguish them from other wasps species.

Family and Relative Species

The square-headed wasp belongs to the family Sphecidae, which consists of various wasp species, including digger wasps, thread-waisted wasps, and more. They share several key characteristics:

  • Most species prey on insects
  • Many have distinctly slender bodies
  • They often have a narrow waist

Let’s briefly explore some of their relatives within the family.

Digger Wasps:

  • Examples: great golden digger wasp, great black wasp
  • Known for their digging behavior
  • Nest in soil

Thread-waisted Wasps:

  • Examples: blue mud dauber, black and yellow mud dauber
  • Recognizable by their elongated waist
  • Prefer to nest in mud

Potter Wasps:

  • Known for constructing small pot-like nests
  • Feed on caterpillars
  • Unique circular shaped nests

Let’s take a closer look at a comparison table of selected species:

Species Nesting Material Prey
Great Golden Digger Wasp Soil Grasshoppers
Great Black Wasp Soil Grasshoppers
Blue Mud Dauber Mud Spiders
Black and Yellow Mud Dauber Mud Spiders
Organ-pipe Mud Daubers Mud Spiders

Remember, this is just a brief overview of the Sphecidae family and some of its notable members. As there’s always ongoing taxonomic tweaking, the classification and relationships might change over time.

Behavior and Habits

Square-headed wasps, also known as sand wasps, are part of the Crabronidae family. These fascinating insects display interesting behaviors and habits that revolve around their nesting and feeding activities.

A key aspect of sand wasp behavior is progressive provisioning for their offspring. They provide their carnivorous larvae with a steady supply of prey. Sand wasps are predators on many kinds of insects, with most of them being fly predators1.

When it comes to nesting, sand wasps prefer sandy or light soil landscapes. You might spot them using their powerful jaws to excavate their nests. These nests often feature dense aggregations, as multiple females can nest in the same area1.

They are also known to show some adaptability in nesting locations. For example, they may utilize hollow stems and the pith of broken stems as alternative nesting sites2.

Here’s a quick overview of sand wasp nesting behavior:

  • Selection of sandy or light soil landscapes
  • Use of jaws to excavate nests
  • Creation of dense aggregations with multiple females
  • Adaptability in utilizing alternative nesting locations such as hollow stems

The lifecycle of a sand wasp involves an egg chamber3 where the female lays her eggs. The wasp then brings paralyzed prey, like beetle larvae, for the growing wasp larvae to feed on. Nourishment from the captured prey allows the wasp larvae to grow and develop4.

Remember, sand wasps play an important role in controlling the population of flies and other insects.

Diet and Predation

Square Headed Wasps are fascinating creatures with an intriguing diet and predatory behaviors. They play an essential role in controlling the population of other insects, which can be both beneficial and interesting to observe.

In their search for sustenance, these wasps are known to consume nectar as a source of energy. This particular diet allows them to garner enough strength to pursue their primary prey: spiders. In fact, Square Headed Wasps are considered a spider’s worst nightmare.

As adept predators, you might find these wasps actively hunting spiders, capturing them with their powerful mandibles. Once they have secured their prey, they often use their venomous sting to paralyze the spider before carrying it off to their nest.

At the nest, the incapacitated spider serves as a food source for the wasp’s developing larvae. Square Headed Wasps are known to be selective in their choice of prey, primarily focusing on spiders like orb weavers and jumping spiders. They also hunt flies, another common insect that often falls victim to their predatory tactics.

Their remarkable hunting skills and preferences can be summarized in the following bullet points:

  • Nectar provides energy for hunting
  • Predominantly hunt spiders (orb weavers and jumping spiders)
  • Flies are also part of their prey list

Square Headed Wasps stand out as highly efficient predators, helping to maintain a balance in the ecosystem. By understanding their diet and predatory habits, you can gain a deeper appreciation for the role these wasps play in our environment. So, when you encounter a Square Headed Wasp, remember its interesting diet and the important role it plays in controlling the populations of its prey.

Geographic Distribution

The Square-headed wasp is an interesting insect with a wide distribution across various regions. In this section, you will learn a bit about where these wasps can be found.

The Square-headed wasp belongs to the subfamily Crabroninae, which includes over 4,700 species worldwide, with about 520 of them found in the U.S. You might encounter these wasps in different parts of the country, depending on the specific species.

These wasps are often spotted in sandy or light soil landscapes. They create their nests in such areas, making it the perfect habitat for them. The nesting sites tend to have large aggregations of females, who work together in building their nests.

When comparing states, it’s important to note that the distribution of Square-headed wasps can vary significantly. Species native to one state might not be found in another. As a result, it is essential to study each region in detail to understand where these insects might reside.

In conclusion, while the Square-headed wasp is found throughout the U.S, their distribution depends on factors like geography, habitat, and the specific type of wasp species. Be sure to keep an eye out for these fascinating creatures when exploring your local area or traveling across the country.

Advice for Naturalists

As a naturalist, you play a crucial role in understanding and preserving our diverse natural world. To share your knowledge and experiences with the Square Headed Wasp, it’s crucial to rely on accurate information and expert professional advice.

One reliable resource for information about insects, including Square Headed Wasps, is BugGuide. This online platform provides detailed information, photographs, and personal accounts from other naturalists and entomologists.

To expand your knowledge further, consider connecting with your local extension office. They often offer resources and expert advice on native insects in your area. By contacting them, you can gain valuable insights into the Square Headed Wasp and other species in your region.

Additionally, utilizing citizen science platforms like iNaturalist can help you document and share your encounters with the Square Headed Wasp. This tool not only enhances your understanding of the species, but also contributes to the larger scientific community’s knowledge.

Remember to stay open-minded, curious, and respectful of the natural world. Unraveling the mysteries of the Square Headed Wasp and other insects will enable you to better appreciate and protect the fascinating world around you.

Additional Species Information

Square headed wasps are fascinating insects that can pique the interest of bug fans and bug ladies alike. Let’s explore some interesting facts and features of these wasps.

Female square headed wasps play important roles in their species, such as laying eggs and parasitizing other insects, like caterpillars. Females also tend to have yellow legs, which can help with identification.

These wasps are often found in the vicinity of milkweed plants. Due to their predatory nature and their preference for other insects, they can be helpful in controlling populations of pests like caterpillars found on milkweed.

Here are some key features and characteristics of square headed wasps:

  • Small to medium-sized, with a characteristic square-shaped head
  • Predatory and parasitoid nature
  • Can be found around milkweed plants
  • Female wasps have yellow legs
  • They can be recognized by their two pairs of wings and distinctive antennae

Comparing square headed wasps with other common wasps can provide insights into their unique attributes. Let’s look at a comparison table highlighting their differences:

Feature Square Headed Wasp Common Wasp
Size Small to medium Medium to large
Head shape Square-shaped Rounded
Legs color (females) Usually yellow Varies by species
Preferred habitat Around milkweed plants Various habitats
Prey Insects, caterpillars Insects, spiders, other prey

Overall, if you spot a square headed wasp around your milkweed plants or in your garden, know that they are likely helping to keep pesky insects in check. Enjoy observing these fascinating creatures as they go about their daily activities, and perhaps even share your newfound knowledge with fellow bug fans.

The Open Source Connection

In the world of software development, the term “open source” often comes up. Open source software is software that anyone can access, modify, and distribute. This leads to greater collaboration, higher-quality code, and a stronger sense of community among developers. Some examples of open source software are Linux and Python.

When it comes to Square Headed Wasps, there is a fascinating connection to the open source concept. The way these insects build their networks and collaborate can be compared to the open source software development process.

Just as developers contribute to open source software by sharing their code, Square Headed Wasps work together to construct their nests, each contributing their own unique skills. The entire network benefits from this collaborative effort.

In both scenarios, clear documentation is essential for success. Like open source developers, these wasps use a form of documentation to communicate with each other and provide instructions to complete crucial tasks within their network.

Here is a comparison table highlighting the similarities between open source software development and Square Headed Wasps:

Open Source Software Development Square Headed Wasps
Collaborative and open to all Work together to build nests
High-quality code High-quality nest construction
Strong sense of community Strong sense of unity within the network
Clear documentation Clear communication to complete tasks

In conclusion, the Square Headed Wasp’s way of life embodies the spirit of open source software development, with collaboration, clear communication, and a shared sense of purpose at its core. As you explore the fascinating world of Square Headed Wasps, remember that their social structure is not too different from the world of software development, especially when it comes to open source projects.


  1. Hortsense 2

  2. Clemson University Extension

  3. UMN Extension

  4. North Carolina State University

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 – Square Headed Wasps


Subject: rose borer wasp?
Location: Floyd County Virginia
August 6, 2014 11:45 am
Cutting off some sickly stems of my knockout roses, I found the stem (about 1/2″ in diameter) to be hollow inside. I slit the stem lengthwise and found these guys inside. I looked them up using whatever search terms I could think of, but found nothing similar. The wasps (?) are about 1/4″+ in length, and they appeared to be newly “fledged”…just beginning to spread their wings. Perhaps they were about ready to bore their way out, having passed through their larval stage?
Signature: Laurel Pritchard

Small Carpenter Bees
Square Headed Wasps

Hi Laurel,
We didn’t think these seemed like the usual suspects, Small Carpenter Bees in the genus
Ceratina, so we checked with Eric Eaton.  Here is his response.

Eric Eaton identified Square Headed Wasps
These are square-headed wasps, family Crabronidae, and probably Ectemnius continuus.  They nest in pith like small carpenter bees, certain mason bees….but they stock the tunnels with paralyzed flies as food for their offspring.  So, still beneficial, just in a different way.

Square Headed Wasps
Square Headed Wasps


Letter 2 – Square Headed Wasp and Nest


Whats this?
Location: Wigan
August 23, 2011 5:56 am
Hi, can you identify what this bug is and if it needs getting rid of? its in my dogs yard and quite near to our front door. I see them coming in and out of the nest frequently.
Signature: Jenny

Square Headed Wasp

Hi Jenny,
As we prepared to post your identification request, we needed to research Wigan since we were uncertain if it was a location or a typographical error.  We did locate a Wikipedia entry that identified Wigan as a town in greater Manchester, England, so we are indicating your location as U.K.  We believe this is a Square Headed Wasp in the subfamily Crabroninae, and we learned on BugGuidethat “Some nest in hollow stems or in abandoned galleries in wood, others burrow in the ground. Prey is mostly flies, but some utilize other insects.”  Assuming that your individual is one that hunts flies, you can determine if you want a predator that reduces the number of flies attracted to your dogs’ feces and potentially entering your front door or not.  These are solitary wasps, and though you may have numerous individuals nesting in the same vicinity, each is excavated by a single female who provisions the nest with flies for her developing larvae.  Solitary Wasps do not defend their nests in the same aggressive manner as social wasps like Yellowjackets.

Square Headed Wasp Nest


Letter 3 – Male Square Headed Wasp: Crabro latipes


Don’t think its a sawfly!
I love your site! I’m always taking pictures of bugs in my garden in Seattle, Washington. But I was really confused by the little "wings" by his head! Can you help identify? Thank-you

Hi Beth,
We searched on BugGuide, thinking this looked like a Square Headed Wasp. We found a photo of a male Crabro latipes that matches along with Eric Eaton’s explanation: “This is, believe it or not, a male sphecid wasp in the genus Crabro, probably C. latipes. His front tibia are greatly expanded into those shields so easily visible here. He covers the female’s eyes with those things during mating. The plates don’t blind her, but apparently filter light in such a way that she recognizes this is a male of her own species. How weird is that? “

Letter 4 – Possibly Square Headed Wasp


Subject: Unknown Pollinator for Orange Coneflower
Location: North Carolina, United States (near Chapel Hill)
September 14, 2014 8:36 am
Hello, I have recently been studying bugs and have been unable to identify the little bugger you see below. The bug itself seems to hang around the orange coneflower (rudbeckia fulgida) quite a bit and always lands on the outer extensions of the head of the flower before heading to the center portion. Thanks!
Signature: Connor McFadden

Possibly Square Headed Wasp
Possibly Square Headed Wasp

Dear Connor,
Your image is not sharp enough to be certain, but we believe this might be a Square Headed Wasp in the subfamily Crabroninae, and it looks similar to this image posted to bugGuide.

Letter 5 – Square Headed Wasp


Subject: Mystery wasp
Location: raymond james stadium FL
October 16, 2015 5:43 pm
based on some peoples opinions, I believe this might be Trypoxylon, but I wanted to here your opinion on it as well.
Thank you!
Signature: Cicada Lover

Square Headed Wasp
Square Headed Wasp

Dear Cicada Lover,
We believe that this is a Square Headed Wasp in the subfamily Crabroninae which is well represented on BugGuide.  Though the subfamily contains the genus
Trypoxylon, we cannot state with any certainty that is the correct classification.  Perhaps one of our readers will supply additional information.

Letter 6 – Square-Headed_wasp


Subject:  bee or wasp
Geographic location of the bug:  Baltimore Ontario
Date: 09/18/2017
Time: 10:11 PM EDT
I found this little guy walking back and forth on a milkweed plant. I did not realize (until I reviewed my photos) that one of his wings is damaged. I feel sorry for the little guy. I don’t know if this is a bee or wasp. I am leaning towards a bee. Hope you can tell me would be great to know. Thanks
p.s. may have sent this twice computer issues.
How you want your letter signed —
terri martin

Square-Headed Wasp

Dear Terri,
The head-on view you provided made it easy for us to identify your Square-Headed Wasp in the subfamily Crabroninae, and though it is not the same species, it looks very similar to this BugGuide image.  Because of the striping pattern on the abdomen, and the yellow legs and antennae, we suspect your individual is in the genus
Crabro like this BugGuide image.

Square-Headed Wasp


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