Mydas Flies: Fascinating Facts About Nature’s Stealthy Predators

Mydas flies are fascinating insects known for their large size and striking resemblance to wasps. They can be found in various parts of North America and are often considered beneficial due to their predatory nature during their larval stage. These eye-catching insects have jet-black bodies with smoky wings, often sporting bright orange markings on their second abdominal segment, making them quite noticeable in nature.

These insects spend a significant portion of their life underground as larvae, feeding on soil-dwelling insects such as grubs. When they pupate, they use specialized spines to move up to the soil’s surface before emerging as adults. Adult mydas flies have a more ambiguous diet, with debate surrounding whether they maintain their predatory habits or shift to nectar-feeding.

Although they may appear intimidating due to their size and appearance, mydas flies are in fact harmless to humans. Their striking looks and unique life cycle provide an interesting subject for entomologists and nature enthusiasts alike, making them a captivating topic for those interested in learning more about the world of insects.

Mydas Flies Overview

Family Mydidae

Mydas flies belong to the family Mydidae and are known for their medium to large size and wasp-like appearance. They have long, clubbed antennae and display a distinctive pattern of curved cells in their wing venation1. Some key features of Mydas flies include:

  • Medium to large size
  • Wasp mimicry
  • Clubbed antennae
  • Curved cells in wing venation

Order Diptera

As members of the order Diptera, Mydas flies are classified as true flies. As true flies, they possess only one pair of wings2. Key characteristics of Diptera include:

  • One pair of wings
  • Short antennae (in most species)

Class Insecta

Mydas flies fall under the class Insecta, which comprises all insects. Insects are characterized by having:

  • Three pairs of legs
  • A three-part body (head, thorax, and abdomen)
  • Usually one or two pairs of wings3

Phylum Arthropoda

Insects, including Mydas flies, belong to the phylum Arthropoda. This phylum is home to the largest group of animals on Earth and includes animals such as insects, spiders, and crustaceans. Arthropods are characterized by:

  • Exoskeleton made of chitin
  • Segmented body
  • Jointed appendages4

Kingdom Animalia

Finally, Mydas flies are part of the kingdom Animalia, which encompasses all animals. Key features of Animalia include:

  • Multicellular, eukaryotic organisms
  • Heterotrophic (obtain food by consuming other organisms) life forms
  • No cell walls5
Taxonomic Rank Mydas Fly Classification
Kingdom Animalia
Phylum Arthropoda
Class Insecta
Order Diptera
Family Mydidae

Physical Characteristics

Size and Length

Mydas flies are known for their large size, typically measuring between 1.0 to 1.5 inches in length. To put this into perspective, they often resemble wasp species like the spider wasps of the family Pompilidae.

Colors and Patterns

These flies display an interesting variety of colors and patterns, such as:

  • Black
  • Dark
  • Tan
  • Red
  • Orange
  • Yellow

Some species even have an attractive combination of these colors in the form of bands, making them stand out visually.

Winged Adult Features

The adult Mydas flies exhibit remarkable features that set them apart from other flies:

  • Two wings: Like all true flies, Mydas flies have just one pair of wings. This is a distinguishing characteristic when comparing them to other insects with more than two wings.
  • Clubbed antennae: Unlike most flies, Mydas flies possess clubbed antennae, similar to those found in butterflies. This unique feature can serve as an identifier when trying to distinguish them from other fly species.
  • Wing venation: Mydas flies’ wings exhibit a distinctive venation pattern, adding to their overall intriguing appearance.

To help visualize the differences between Mydas flies and other fly species, here’s a comparison table:

Feature Mydas Flies Other Fly Species
Size and Length Large (1.0-1.5″) Varies
Colors/Patterns Diverse Varies
Wings Two wings Two wings
Antennae Clubbed antennae Varies
Wing Venation Distinct Varies

Behavior and Habitat

Diet and Feeding Preferences

Mydas flies adults are known to feed on nectar, flowers, and pollen. They mostly prefer white flowers with open structures that provide easy access to nectar sources:

  • Nectar
  • Flowers
  • Pollen

For example, flies are attracted to plants like rattlesnake master in gardens. Mydas fly larvae, on the other hand, act as predators and feed on grubs of beetles in soil and rotting wood, providing biological control of pests.

Mating and Reproduction

Limited information on mating and reproduction of Mydas flies is available from the search results provided.

Range and Distribution

Mydas flies inhabit various environments across North America, including tropical, subtropical, and dry regions:

  • Tropical forests
  • Subtropical grasslands
  • Woodlands
  • Meadows
  • Prairies
  • Desert Southwest and dry areas, such as Sonoran Desert summer

Below is a comparison table of some habitats where Mydas flies are found:

Habitat Region
Tropical forests Various locations
Subtropical grasslands Various locations
Woodlands North America
Meadows U.S.
Prairies North America
Desert Southwest Sonoran Desert summer

Mydas flies are considered wasp mimics, also known as Batesian mimicry. This means they resemble wasps, which helps deter predators, but they are actually harmless. Their role in conservation includes their predatory nature, helping control pest populations, and their involvement in pollination as they visit flowers in search of food sources.

Life Cycle and Development

Egg

Mydas flies, like other insects, start their life as eggs. The female lays eggs, and when they hatch, grublike larvae emerge. These larvae have the primary objectives of eating and growing during this stage in their life cycle.

Larval Stage

The larval stage is vital for the development of Mydas flies, as they spend most of their lives in this stage. It’s common for Mydas flies to spend at least a year as a larva, during which they molt several times.

  • Early instars feed on beetle grubs
  • Late instars switch to a more armored source like prey eggs

A well-known Mydas fly is the Mydas clavatus. Their larvae are known for feeding on beetle grubs, helping to control beetle populations in the environment.

Pupal Stage

When a Mydas fly larva is ready to transform, it undergoes the pupal stage. The pupa is the stage where the insect metamorphoses into an adult Mydas fly. The duration of the pupal stage varies depending on environmental conditions and species.

Adult Stage

During the adult stage of the Mydas fly life cycle, they focus mainly on reproduction. Adult Mydas flies resemble wasps, but they are harmless. They typically have darker colors like black, dark, or tan, with red, orange, or yellow bands. Like all true flies, they have only one pair of wings and clubbed antennae.

Characteristics of Adult Mydas Flies:

  • One pair of wings
  • Clubbed antennae, similar to butterflies
  • Wasp-like appearance, but harmless

In conclusion, the life cycle of the Mydas flies consists of the egg, larval, pupal, and adult stages. Mydas clavatus, a well-known Mydas fly, helps control beetle populations, providing essential ecological benefits. Their unique wasp-like appearance, clubbed antennae, and roles in their environment make them fascinating subjects to study.

Interactions and Relationships

Batesian Mimicry

Mydas flies exhibit Batesian mimicry, which means they resemble wasps in appearance, but they are actually harmless. This helps protect them from potential predators that would be deterred by a dangerous-looking insect. They often have black, dark, or tan bodies with red, orange, or yellow bands.

Predators and Prey

  • Larvae: Mydas fly larvae are predators of soil-dwelling insects, such as beetle grubs found in soil and decaying wood. Due to their feeding habits, they have been proposed as a biocontrol agent for sod farms to control root-eating beetle grubs that can damage lawns.
  • Adults: There is debate regarding the feeding habits of adult Mydas flies. Some scientists believe they may continue to be predators, while others suggest they might be nectar feeders.

Footnotes

  1. https://genent.cals.ncsu.edu/insect-identification/order-diptera/family-mydidae/
  2. https://mdc.mo.gov/discover-nature/field-guide/mydas-flies
  3. https://education.mdc.mo.gov/discover-nature/field-guide/mydas-flies
  4. https://arthropod.uark.edu/mydas-fly/
  5. https://www.canr.msu.edu/news/michigan-insects-in-the-garden-season-2-week-10-mydas-flies

Authors

    by
  • Bugman

    Bugman aka Daniel Marlos has been identifying bugs since 1999. whatsthatbug.com is his passion project and it has helped millions of readers identify the bug that has been bugging them for over two decades. You can reach out to him through our Contact Page.

    View all posts
  • Piyushi Dhir

    Piyushi is a nature lover, blogger and traveler at heart. She lives in beautiful Canada with her family. Piyushi is an animal lover and loves to write about all creatures.

    View all posts

25 thoughts on “Mydas Flies: Fascinating Facts About Nature’s Stealthy Predators”

  1. Is it common for this bug to be in south eastern Massachusetts? If not would it be considered to be an evasive species?

    Reply
  2. We have a very large fly that is burrowing underneath our raised patio. It appears to be all black in color. Do mydas flies burrow or could it be something else? Could they cause damage? We are in upstate ny.

    Reply
  3. Mydas Fly in Gila Bend, AZ
    /Users/Hubbard/Pictures/Photos Library.photoslibrary/Thumbnails/2015/07/31/20150731-173624/yWg03wpnSzmXeOLvJWl9vQ/thumb_IMG_3558_1024.jpg

    Reply
  4. Hello everyone.Ok i live in south Georgia and while sitting in the back yard i spotted this red bodied with black wings that did more crawling around but did fly away.It was not aggressive.I’m trying to figure out what it is.I never seen this bug before.The closest i found out was it being a Mydas fly but does not look exactly like the mydas fly.anybody got any more imfo to share.Thanks………………………..Brian J

    Reply
  5. I had a similar species in my garden this afternoon (SE IN). It had a fatter abdomen and was flying around marigolds. It had been in a hibiscus plant that had caterpillars all over it and I disturbed it when I was moving the leaves. It had the same kind of wings but a more distinct and varied pattern of black, yellow and orange striping. It flew off before I could run inside and get my camera.

    Reply
  6. A very special, and beautiful, fly!! And, though a large wasp mimic…totally harmless to humans!

    The mydas fly here is definitely in the genus Opomydas, and my best shot would be O. limbatus…which has a record from Whitewater Canyon (at ~1000′ elevation) on June 26, 1976.

    This species is not yet represented on BugGuide, and would be a wonderful addition! It would be great if Christina would register on BugGuide (super-easy to do at http://bugguide.net/user/register ) and then post this image. Then BugGuide experts could work give a definitive ID it, and leave comments under Christina’s BugGuide post documenting the process.

    Reply
    • Thanks so much for the identification. We don’t know if Christina will log onto this posting again, but hopefully she will take your advice.

      Reply
  7. A very special, and beautiful, fly!! And, though a large wasp mimic…totally harmless to humans!

    The mydas fly here is definitely in the genus Opomydas, and my best shot would be O. limbatus…which has a record from Whitewater Canyon (at ~1000′ elevation) on June 26, 1976.

    This species is not yet represented on BugGuide, and would be a wonderful addition! It would be great if Christina would register on BugGuide (super-easy to do at http://bugguide.net/user/register ) and then post this image. Then BugGuide experts could work give a definitive ID it, and leave comments under Christina’s BugGuide post documenting the process.

    Reply
  8. Oops…realized I misspelled Christena’s name after I made posting my previous comment. (My apologies to you, Christena, if you read this!)

    I do hope Cristena sees my comments here (e.g. if, per chance, comments generate an email alert to the person originally posting?) It turns out there are a number of interesting members of Mydidae that range in the Whitewater/Palm Springs area, and she may find more as she and her children are in the habit of rescuing interesting bugs from her pool 🙂 So it would be good for them to know that mydids (of all kinds) are harmless to humans, and thus “safe to save”.

    And if the opportunity arises, good diagnostic photos would include details of the hind legs; wing venation; and a profile of the head showing antennae and mouthparts as clearly as possible.

    Reply
  9. Oops…realized I misspelled Christena’s name after I made posting my previous comment. (My apologies to you, Christena, if you read this!)

    I do hope Cristena sees my comments here (e.g. if, per chance, comments generate an email alert to the person originally posting?) It turns out there are a number of interesting members of Mydidae that range in the Whitewater/Palm Springs area, and she may find more as she and her children are in the habit of rescuing interesting bugs from her pool 🙂 So it would be good for them to know that mydids (of all kinds) are harmless to humans, and thus “safe to save”.

    And if the opportunity arises, good diagnostic photos would include details of the hind legs; wing venation; and a profile of the head showing antennae and mouthparts as clearly as possible.

    Reply
  10. I have looked all over trying to find this fly! I have them in my vegetable garden. I too thought it was a beautiful wasp and watched with delight as it stopped on every plant!

    Reply
  11. I just saw a mating pair connected flew by me and landed on a tree I live in Putnam county,NY amazing looking fly!

    Reply
  12. We just found a large one in our backyard today (7/20/2019) in metro Phoenix, Arizona. It looked just like the picture above, black upper-body and wings with a full orange-lower body. It was huge, about 2 inches. We captured it in a jar and inspected it before letting it go. It certainly looked like a giant fly with the shape of the eyes, long mouth parts, legs and antenna.
    I’ve lived in Arizona my whole life and never seen one before. Are they native to Arizona?
    Thanks

    Reply
    • We cannot currently access BugGuide to verify the range of Archilestris magnificus, but this FlickR image from Arizona leads us to believe it is a local species for you.

      Reply
  13. I just happened on this site while searching for ID on an unfamiliar insect seen in my garden area today. It was on an old wood pile and flew away quickly into nearby Green Giant Thuja trees. There appeared to be two of them. I am glad to know it is not an invasive or destructive pest.

    Reply
  14. Hi I saw something like it but top and was orange and bottom was was purple front was black head it was very pretty non aggressive it that the same thing or something else

    Reply
  15. I live in Christiansburg VA.
    While flipping my compost pile a jet black wasp with an orange band landed.I never seen one until yesterday.after a Google I came across this site.It is a mydas fly so glad it’s not a wasp that stings.

    Reply
  16. I have these bugs in my backyard and there’s lots of them flying around my lawn and I said hundred of them and they look like mydas fly but they are tiny with orange but and black body. Can someone tell me if they have this kind of bug in their backyard? I noticed them a couple months ago, they are the size of a regular fly but cuter they are fast.

    Reply

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