Scoliid Wasp: Quick Guide to Identification and Behavior

Scoliid wasps are fascinating insects that often go unnoticed by many people. These wasps are robust, slightly hairy creatures with unique coloration, including dark or metallic shades and patterns of yellow spots. Their large size and solitary nature make them intriguing subjects for those interested in learning more about the insect world.

As you explore the world of scoliid wasps, you’ll discover that they play an important role in controlling beetle populations. Females search for beetle grubs in soil, sting them to paralyze, and then lay their eggs on the grubs. The wasp larvae feed on the grubs, effectively controlling their numbers in the natural environment.

One of the most common species, especially in North Carolina, is the blue-winged wasp (Scolia dubia) known for its stunning metallic blue wings and black antennae. Thanks to their interesting behaviors and appearances, scoliid wasps make a captivating topic of discussion for anyone eager to delve into their world.

Physical Characteristics

Color

Scoliid wasps have a unique color combination which makes them easily identifiable. Their main body is usually a deep blue-black shade, with yellow stripes on the sides of their abdomen and blackish-purple wings. The hairs covering their body can range from reddish to yellowish in color.

Size

These wasps are not very large but have a substantial size, measuring typically around 5/8 inch long. Their stout bodies make them look more robust and resilient, which helps them in their daily tasks and hunting habits.

Distinct Features

Scoliid wasps have a few characteristics that make them stand out:

• They are covered in hairs, with longer hairs on the back part of their abdomen
• Yellow stripes on the sides of their abdomen are a noticeable pattern
• Their blackish-purple wings are a distinct trait that makes them more recognizable

Males Vs Females

There isn’t a significant difference between male and female scoliids in terms of appearance, but you can spot some minor distinctions. Here is a comparison table to make it easier to identify the genders:

It’s important to remember that both male and female scoliid wasps play vital roles in controlling the population of soil-inhabiting scarab beetle larvae, ensuring the preservation of a healthy ecosystem.

Behavior and Habits

Daily Activities

Scoliid wasps are mostly active during the day. They can often be seen flying around in search for food. These wasps enjoy a wide variety of flowers, such as white clover and mountain mint.

Their primary target, however, are soil-inhabiting scarab beetle larvae. Scoliid wasps are not only fascinating creatures, but they also help control the population of these beetles by acting as their natural predators.

Seasonality

You may spot Scoliid wasps primarily in late summer, particularly in the early evening. They are more active at this time due to the increased number of scarab beetle larvae which are more abundant during late summer months. Keep in mind the following points regarding their seasonal behavior:

• Active during the day, particularly early evening
• Late summer sightings are more common

As the season progresses, Scoliid wasps will gradually disappear, signifying an end of their active season. This pattern allows them to sync with the life cycle of their prey, the scarab beetle larvae.

Habitat and Geographic Range

North America

Scoliid wasps are ground-nesting insects commonly found in gardens and lawns throughout North America. They favor soil-inhabited areas where their primary prey, scarab beetle larvae, are present. One of the most common species in the United States is the Scolia dubia, also known as the blue-winged wasp¹. This species is particularly prevalent in states like Florida and other parts of the southeast².

Worldwide Distribution

While Scoliid wasps’ habitat can vary, they are typically found in areas with warm climates. Besides North America, they can also be found in other regions such as:

• Europe
• Asia
• Africa
• Australia

Regarding their distribution across these areas, Scoliid wasps are not as widespread in the southwest of the United States compared to the southeast³. This regional variation might be due to differences in environmental factors or availability of prey.

Life Cycle of Scoliid Wasps

From Egg to Larva

Scoliid wasps have a fascinating life cycle that begins with the female wasp laying an egg. The female digs into the soil to find a beetle larva, stinging and paralyzing it before laying her egg on it. This provides the developing wasp larva with a nutritious food source.

As the scoliid wasp larva grows, it feeds on the paralyzed beetle larva. The feeding process usually lasts a few weeks until the wasp larva has consumed the entire beetle larva, ultimately leading to the pupation stage.

Adult Stage

Once the wasp larva reaches maturity, it transforms into the adult stage. Adult scoliid wasps are large, hairy solitary wasps and are often handsomely colored. Their body colors typically range from dark or black with yellow, red, or white patterns.

Adult scoliid wasps have two primary objectives: mating and laying eggs. They are not aggressive towards people, and their primary focus is searching for beetle larvae to lay their eggs on. During the adult stage, scoliid wasps also play a crucial role in pollinating plants as they feed on nectar.

In summary, the life cycle of scoliid wasps begins with the egg-laying stage, followed by the larval feeding stage, pupation, and finally, adulthood. These wasps are essential contributors to ecosystems by controlling beetle populations and assisting with plant pollination.

Diet and Prey

Adult Diet

In their adult stage, Scoliid wasps are mostly nectarivorous creatures. They get their energy from consuming nectar and pollen from a variety of flowers. For instance, Scoliid wasps are known to enjoy white clover and mountain mint. These wasps do not pose a threat to people, and their presence can actually help with a garden’s pollination.

Larval Diet

On the other hand, Scoliid wasp larvae have a different type of diet. They primarily feed on beetle grubs, such as the Japanese beetle and Green June beetle. The adult female wasp digs into the soil and searches for these beetle grubs. Once she finds one, she will paralyze it with a sting and lay her egg on it. When the larva hatches, it consumes the grub as its primary food source, acting as a natural form of biological control for these beetles.

The diet and prey preferences of Scoliid wasps showcase their unique adaptive characteristics—nectar and pollen consumption for adult wasps, while increasing their larvae’s chances of survival by targeting specific beetle grubs.

Classification and Species

Scoliidae Family

The Scoliidae family consists of fairly large, stout-bodied wasps, often brightly patterned in red and yellow, white, or one of these colors in combination with black. They are commonly known as Scoliid wasps, and they can be found around the world, primarily in tropical and subtropical regions¹. These wasps are known for their parasitic relationship with soil-inhabiting scarab beetle larvae².

Notable Species

• Scolia dubia: One of the most common Scoliid wasps, Scolia dubia is sometimes referred to as the blue-winged wasp³. The adult is over one-half inch long with black antennae and a dark body, often metallic, with light yellow spots or other markings. Their wings are blackish purple with a metallic blue sheen⁴.

• Scolia guttata: This species can be identified by a series of yellow markings on a mainly black body. It is similar in size and shape to other Scoliid wasps.

• Scolia mexicana: A species found in Mexico and southern regions of the United States, Scolia mexicana features a dark-colored body with distinctive red markings.

• Genus Scolia: Within the Scoliidae family, Scolia is a diverse and widespread genus, containing many different species. They share similar characteristics such as size, metallic coloration, and parasitic behavior on scarab beetle larvae⁵.

• Genus Xanthocampsomeris: Another notable genus within the Scoliidae family, Xanthocampsomeris species can be identified by their yellow markings on a black body. Like other Scoliid wasps, they are parasitoids of scarab beetle larvae⁶.

In conclusion, the Scoliidae family comprises various species of Scoliid wasps that share unique coloration and ecological interactions with soil-dwelling scarab beetle larvae. By understanding the different species and classifications, you can better appreciate the diversity and ecological roles of these fascinating insects.

Interaction with Humans

Stings and Aggression

In general, Scoliid wasps are not aggressive towards humans. They usually go about their day searching for food and mates without bothering you. However, if they feel threatened or believe their nest is in danger, they may sting in self-defense. It is essential to remember that a sting from a Scoliid wasp can be painful, but typically does not pose a significant risk to humans, as it is a solitary wasp, unlike social wasps.

If you happen to get stung by a Scoliid wasp, it is recommended that you clean the area thoroughly with soap and water, then apply a cold compress to help minimize swelling. It might also be a good idea to take pain relievers or antihistamines to ease discomfort and reduce inflammation.

In the Garden

Scoliid wasps can be considered beneficial insects when it comes to your garden. These wasps are natural predators of grubs, particularly those of Japanese beetles and June bugs. The female lays her eggs on the grubs, and once the eggs hatch, the young wasps feed on the grubs, helping to control their population.

When you see Scoliid wasps in your garden, it’s a sign that you might have a grub infestation. They are nature’s way of trying to bring balance to your garden’s ecosystem. So, instead of perceiving them as a threat, you can appreciate their role in pest control.

Remember, the key is to respect their presence and allow them to carry out their essential role in your garden. In return, they will help you maintain a healthy ecosystem without posing any harm to you or your plants.

Beneficial Role and Impact

Ecological Roles

Scoliid wasps play a vital role in maintaining the balance of ecosystems. They are known for their parasitoid behavior, targeting soil-inhabiting scarab beetle larvae. When a female wasp finds a beetle grub, she stings it and lays an egg on it. The wasp larva then feeds on the beetle grub, eventually killing it¹. This helps keep the beetle population in check, preventing them from becoming a nuisance in your garden.

Pollination and Pest Control

In addition to their ecological role, scoliid wasps are also beneficial pollinators. While searching for nectar, they inadvertently transfer pollen between flowers, contributing to the pollination process². As pollinators, scoliid wasps help maintain the biodiversity of your garden, allowing different plant species to continue thriving.

Moreover, their ability to control beetle populations is a form of natural pest control. By controlling the number of soil-dwelling beetle larvae, scoliid wasps prevent these pests from damaging the roots of your garden plants³. This offers you an environmentally friendly alternative to chemical pesticides.

In conclusion, scoliid wasps are beneficial insects to have in your garden. They play important roles in maintaining ecological balance, acting as pollinators, and serving as a form of natural pest control.

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 – Scoliid Wasps: Campsomeris ephippium

Wasp
I emailed you once before about these humongous awesome wasps. They are still visiting us from time to time. They seem to like the passionflower vines and blossoms. I live northwest of San Antonio, Texas. If possible I’d like to have an ID on these. Thanks.
Linda Williams

Hi Linda,
We will need additional time to research the species, but we are relatively certain this is a Scoliid Digging Wasp in the Family Scoliidae. Texas is one of the states that often makes identification more difficult because of the proximity to Mexico. Often tropical species that are not found in U.S. Guidebooks can be found in more localized areas. We will confer with Eric Eaton to see if he recognized your gorgeous wasps. Eric Eaton responded: “You are correct on both counts. I don’t recognize the scoliids to species, and actually don’t know of any specialists on that family, either. We’d love to have both the images in Bugguide, too, as we are low on Urocerus images, and I don’t think that particular scoliid is as yet represented there. Eric”

Update January 20, 2016:  Campsomeris ephippium
Thanks to a comment that just arrived, we went back to this 2006 posting and then turned to BugGuide to attempt an ID.  Seems the species Campsomeris ephippium is now represented on BugGuide, but the oldest posting there is 2008, two years after we first posted this image.  We are happy we finally have an ID on this gorgeous Flower Wasp or Mammoth Wasp or Scarab Hunter Wasp, all common names for the family members.  This species has only been reported from the southern portions of Texas and Arizona.

Letter 2 – Scoliid Wasp

yellow n orange wasp
hello again, so now i found this one on the desert milkweed……. and did not seem to find it in your listing, could you id for me…. tx,
Jim and Daniele BOLLER
Surprise, Arizona

Hi Jim and Daniele,
We found a match for your wasp on BugGuide. It was identified as Trielis octomaculata.

Letter 3 – Moroccan Wasps

Location: Morocco
November 24, 2016 10:09 am
Dear Daniel Marlos:
Just happened upon your site and decided to let you know about my own minor efforts in entomology. I spend a good deal of my time (retired) in Morocco and one thing I do is take photos of all sorts of subjects, including plenty of ‘bug’ pictures – especially bees and butterflies. Many are as yet to be uploaded since I’m trying to learn the basics about taxonomy but, alas, it’s slow going!
… Thanks for any help or suggestions you might offer.
Signature: Jearld Moldenhauer

Dear Jearld,
WE believe the hairy Hymenopteran is a Scarab Hunter Wasp in the family Scoliidae.  Here is an image that looks similar that is posted to PicClick, but we can’t find any information on the species.  Though the colors are quite different, the body morphology of this Scolia dubia posted to BugGuide looks similar to that of your individual.  Your other wasp might be a Paper Wasp in the subfamily Polistinae.

Letter 4 – Giant Scoliid Wasp from Ecuador

Subject:  Pygodasis ephippium wagneriana
Geographic location of the bug:  Ecuador
Date: 08/22/2021
Time: 10:41 PM EDT
Your letter to the bugman :  It’s dead so I can take tons of pics for more research.
How you want your letter signed:  Paola Davalos

Dear Paola,
This is definitely a wasp in the family Scoliidae, sometimes called Digger Wasps.  Scoliid Wasps prey on the grubs of Scarab Beetles.  This might be Pygodasis ephippium, The Giant Scoliid Wasp, which is pictured on Project Noah where it states:  “A truly monstrous wasp measuring 4 cm in length! This is a Scollid wasp, often called Digger Wasps. They have a characteristically corrugated pattern on the tips of the wings (2nd picture). These are parasitic on Scarab larvae under ground, tunneling down to the larva to lay her egg on its body. Some will make a side chamber to store the larva while her own offspring grows. Because of her size, she must parasitize one of the larger scarab species. She also has enormous mandibles (1st & 5th pictures) for handling the larva underground. This species has two large orange-red bands on the abdomen and is otherwise entirely black. This is the 4th individual I have seen over the past 30 years. These have been reported from the southern US, Mexico, Central America and northern South America “

Letter 5 – Scoliid Wasp from Arizona

Bug covered in pollen
November 12, 2009
I photographed this bug near the San Pedro River 5 miles east of Sierra Vista, AZ August, 26, 2008. It caught my eye because it was covered in pollen. I am interested in knowing what it is called.
Juanita
South East Arizona near San Pedro River

Hi Juanita,
We are requesting assistance from Eric Eaton with your identification.  We believe this is a Scoliid Wasp or Flower Wasp, a family that takes nectar and pollen as an adult, and feeds upon Scarab beetle grubs as a larva.  The Scoliid Wasps are robust wasps with hairy bodies that will attract pollen.  Your photo doesn’t show any markings on the abdomen, but we believe your specimen may be Scolia nobilitata, as pictured on BugGuide.

Eric Eaton Concurs
You are correct.  So much pollen that I can’t make out which genus, let alone species:-)
Eric

Thank you for your information.  I too have been searching other web-sites and have seen a similar picture at the following site:
http://www.flickr.com/search/groups/?q=Wasp&w=1115180%40N22&m=pool
The third photo does show a Scolid Wasp that looks very much like the insect I photographed.  The individual who took the picture did so in South East Arizona about 70 miles from the place where I took the photo.
Juanita

Letter 6 – Scoliid Wasp

Bee fly
Sat, Jun 20, 2009 at 9:55 AM
I racked my brain trying to figure out what species bee this is, only to find out it’s not a bee at all. I’m still having trouble determining which genius it is. It has a very bright orange color. And is about the same size as a Bumble Bee.
Sincerely, Audrey Wilkison
Long Island, New York

Hi Audrey,
This is a Scoliid Wasp, a family of wasps that parasitizes the grubs of Scarab Beetles, especially June Beetles.  Scoliid Wasps are large, robust, hairy wasps. Your photos are quite blurry, so we are not certain of the exact species identification, but we believe this may be Scolia nobilitata which is pictured on BugGuide.  According to BugGuide, its “Range Includes southeastern United States. Noted from Illinois, West Virginia, North Carolina, south Florida.”   We would have eliminated the larger Campsomeris quadrimaculata because BugGuide indicates it is found “Throughout Southeastern United States,” yet there is  one report on BugGuide from New Jersey and it was in June.  Again, your photos look too blurry to be certain, but we believe your specimen looks more like Campsomeris quadrimaculata, and the sighting from New Jersey makes that a distinct possibility.