Picture Winged Fly Facts: Unveiling the Tiny Insect’s World

Picture-winged flies are fascinating insects closely related to fruit flies. They get their name from the striking patterns adorning their wings, which often display colorful spots or bands. Some species are even known to wave their wings in circles while perched as if they are rowing, adding to their visual appeal.

Not only are their wings uniquely patterned, but the body shape of many picture-winged fly species closely resembles that of ants. A common example, Delphinia picta, features a distinctively large snout that makes their face appear similar to an old-style gas mask. These fascinating features make picture-winged flies a captivating subject of study for entomologists and nature enthusiasts alike.

Picture Winged Fly Overview

Identification and Appearance

Picture-winged flies are small insects belonging to the family Ulidiidae. They are characterized by their:

• Striking patterns of spots or bands on their wings
• Ant-like body shape

For example, the Delphinia picta species has a large snout, giving its face an appearance similar to an old-style gas mask¹.

Species and Distribution

While there are many species of picture-winged flies, they can commonly be found in North America and other regions. Some species, such as those in the genus Drosophila, make up a significant portion of the insects found in Hawai’i².

Comparison Table

Biology and Behavior

Life Cycle

The life cycle of the picture-winged fly consists of four stages, including egg, larva, pupa, and adult. Female flies lay eggs using their ovipositor on suitable material for larvae to feed on.

• Egg: Usually laid near decaying plant materials, where larvae will find a food source.
• Larva: Upon hatching, larvae consume organic material and grow through several instar stages.
• Pupa: The larval stage ends when they form a cocoon-like structure, called pupa, where they undergo metamorphosis.
• Adult: Upon emerging from the pupa, the adult picture-winged fly is ready to mate and reproduce.

Diet and Feeding Habits

Picture-winged flies, akin to fruit flies, usually feed on decaying plant matter. Their spotted and banded wings are used not only for flight, but also to display during mating rituals.

Features of Picture-Winged Flies:

• Antlike body shape
• Spotted or banded wings
• Some species wave their wings in circles while perched

Comparison Table: Picture-Winged Flies vs. Fruit Flies

One noteworthy example, the Delphinia picta, has a large snout that resembles an old-style gas mask. These fascinating flies provide insight into the diverse biology and behavior of insects that share unique features and different feeding habits depending on their environment.

Relationship with Humans and Environment

Impact on Agriculture

Picture-winged flies are generally considered harmless. These flies belong to the family Ulidiidae, which is different from fruit flies (Tephritidae) that typically affect agriculture. Their unique wing patterns and large snouts make them easy to distinguish from more harmful species like lance flies, flutter flies, and signal flies. For instance, Ceroxys latiusculus is an example of a picture-winged fly that does not pose a significant threat to crops.

Indoor Infestations

Occasionally, these flies may find their way into homes, usually attracted by decaying matter, sap flows, nectar, or rotting vegetation. They might gather near windows, as they are drawn to light sources. However, picture-winged flies are not typically associated with indoor infestations or major issues in human environments. Their preferred habitats are more natural settings such as garbage dumps and areas with rotting organic matter.

Comparison Table: Picture-Winged Flies vs. Fruit Flies

Picture-Winged Fly Features:

• Unique wing patterns
• Harmless to agriculture
• Prefer rotting vegetation and garbage dumps

Fruit Fly Characteristics:

• Less distinct wings
• Cause crop damage
• Frequent human environments

Natural Predators and Defense Mechanisms

Antlike and Gas Mask Features

Picture-winged flies have some unique features that help them defend against predators. For instance, they often have an antlike body shape, which may deter potential enemies due to ants’ reputation for being aggressive and unappetizing. A common species, Delphinia picta, is characterized by a remarkably large snout resembling an old-style gas mask¹. These physical adaptations provide camouflage and mimicry, contributing to the fly’s defense mechanisms.

Common Predators

As for their predators, picture-winged flies face threats from various creatures like:

• Spiders²
• Birds
• Other larger insects

Overall, picture-winged flies employ both their antlike and gas mask features, as well as their unique wing patterns to evade numerous predators found in their habitat.

Additional Picture-Winged Fly Facts

Moist Habitats

Picture-winged flies, or Otitidae, are closely related to fruit flies and are known for their striking wing patterns. They are commonly found in moist areas, such as:

• Wetlands
• Marshes
• Garden edges near water sources

These insects are mostly active during late summer and fall, preferring to lay eggs in or near rotting vegetation, seed heads, or in small gaps in submerged plants.

Potential for Biting

Although picture-winged flies are often mistaken for biting insects, they are not known to bite humans. Their bite is primarily reserved for their prey, as some species are predatory. However, it’s essential to accurately identify these flies, as they can resemble other insects capable of biting, like certain mosquitoes or flies.

Comparison table: Picture-winged flies vs. Mosquitoes:

Keep in mind that the scientific name for picture-winged flies is Otitidae. So, when observing these insects in their moist habitats, remember that while they appear similar to mosquitoes, their unique wing patterns and lack of biting behavior set them apart from their more bothersome relatives.

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 – Picture Winged Fly

Subject: Odd ant – wasp looking creature
Location: Cumming, Georgia
July 18, 2014 8:47 am
I have a vegetable garden and this guy hangs out on the outer leaves, he will walk in a complete circle over and over or just hang out on the leaf, he seems to be busy doing something but I can’t tell what. He flies from leaf to leaf and is about 1/2 in long. I have been told to kill it because it doesn’t look like it would be a beneficial bug, but I won’t until I know for sure he is not a good bug for the garden. He has been here since beginning of season, May and still here now, July, with a couple more buddies. The wing colors vary on each, but body color and shape stays the same. I say he because he kind of looks like a bada##!
Signature: Robyn Hood

Dear Robyn Hood,
This attractive fly is a Picture Winged Fly, Delphinia picta, and according to BugGuide, it:  “Breeds in decaying organic matter, such as compost”  so you don’t need to worry about the Picture Winged Fly harming your garden.  More information is available on the Featured Creatures site, which states:  “Larvae of this fly feed on accumulations of badly decayed, sodden vegetation lying on the surface of the ground or partially buried in the soil, on rotting fruit, and on other kinds of decomposing vegetation, including bulbs of commercial onions and wild garlic … In northeastern Ohio, adults were found most commonly on herbaceous vegetation near garbage dumps and refuse heaps. “

Letter 2 – Picture Winged Fly

ant type insect with black wings
Location: Lexington, KY
May 7, 2011 1:11 pm
as of yesterday, I have many of these on both of my cars and walking along the front of my painted brick house and my neighbors stone house. (I live in Lexington, KY) Thanks for helping me to identify these and possibly assist me in treatment to use if they are destructive.
Signature: Diane Davis

Dear Diane,
The Picture Winged Fly, Delphinia picta, is a common species that according to BugGuide:  “Breeds in decaying organic matter, such as compost.”  Perhaps you have a compost pile or a newly fertilized lawn that is causing the significant numbers of Picture Winged Flies near your home.

Letter 3 – Picture Winged Fly

Better photos (hopefully) of” Looks like an ant but has strange wings”
August 8, 2009
Here are some new photos, maybe they are better than the last one I submitted. I am stumped, Bugman. Is this a fly or an ant? I see them on the west side of my house usually in the morning before it gets too hot. I have looked at hundreds of photos of flying insects on your site and on the web and have yet to figure out this mystery bug. They are the size of an ant with one pair of black roundish wings. Can you solve the mystery?
Kristin N.
Dallas, Texas

Hi Kristin,
This is a Picture Winged Fly, Delphinia picta, and according to BugGuide, it:  “Breeds in decaying organic matter, such as compost.”  ONe reader once described its head as looking like that of a horse.

Letter 4 – Two Picture Winged Flies including Black Onion Fly and a Signal Fly

3 different flies with patterned wings
November 29, 2009
Here are 3 similar but different flies that were all sitting near each other. Two were perched on squash leaves in a vegetable garden. The very black one (in the last photo) was nearby on a wall near a sunflower. I took the photos on July 23rd and it was a warm sunny day. They were all smaller than the common housefly. And the black one was larger than the other two. They all look related but the wing patterns are different on each one. The 2nd pic fly is eating a bird (or teeny lizard) dropping. Could one (or more) of them be a walnut husk fly? Our neighbor has a walnut tree. Is it just a coincidence that they are hanging out together?
I aalso have photos of a green jumping spider protecting her eggs…I photograghed daily until the eggs hatched, little spiderets everywhere and mom had left. I don’t need any identification, just wondering if you’d like me to send some pics of the process.Thank you……
swarner
Fredericksburg, VA

Hi swarner,
We have been very busy recently, and today we are randomly selecting older letters to look for good postings.  Your photos are awesome.  We believe all three of your flies may be Picture Winged Flies in the family Ulidiidae, and we have conclusively identified the Black Onion Fly, Tritoxa flexa, on BugGuide.  The species if found over much of North America, and it is associated with cultivated garlic.

A second Picture Winged Fly is Delphinia picta, also found on BugGuide, and it breeds in compost piles.  The two white triangles on the leading edge of the wings is a distinguishing feature.

Continued searching revealed your final fly to be a Signal Fly in the genus Rivellia.  According to BugGuide, they are found on foliage feeding on feces, exactly as your photo depicts.

Letter 5 – Picture Winged Fly

Winged ant?
May 1, 2010
I have seen this insect many times in Texas. The wings are oriented in a peculiar way on the thorax. They fan out rather than lay flat on the back. What is this insect and does it sting? Perhaps it is a fly?
Taylor
Texas

Hi Taylor,
You have submitted an image of a Picture Winged Fly, Delphinia picta.  According to BugGuide it:  “Breeds in decaying organic matter, such as compost.“

Thank you for the speedy response! You have a wonderful website!
Best,
Taylor

Letter 6 – Picture Winged Fly

Subject: Odd fly/wasp
Location: Charles Town, WV
August 11, 2016 9:06 am
Found in garden near Charles Town WV. What is it?
My neighbor found it, she is a Bee Keeper hoping this isn’t some weird bee thing!
Signature: Becky

Dear Becky,
This is a female Picture Winged Fly, Delphinia picta, and what appears to be a stinger is actually her ovipositor, as is evident in these BugGuide images.  According to BugGuide:  “Breeds in decaying organic matter, such as compost” and if your neighbor has bees and is an avid gardener, we suspect there is a nearby compost pile that Picture Winged Flies might find attractive.

Wow! Thank you very much! Yes, she does have garden compost. She will definitely appreciate this info.
Becky

Letter 7 – PIcture Winged Fly from South Africa

Subject: what insec
Location: standerton, south africa
August 29, 2015 9:17 am
I have never seen this insect before, living in the same town for 30 years….
Signature: solene

Hi Solene,
This reminded us of a Fruit Fly in the family Tephritidae, so we searched iSpot for South African species, and though we did not find an exact match, we did find several images that looked very similar, including this iSpot posting, though it is only identified to the family level.  The common name for the family in South Africa is Picture Winged Fly, but that same name is used on iSpot for the family Ulidiidae as well.  We are confident that in South Africa, Picture Winged Fly is an appropriate name for your individual, though we cannot say for certain to which family it belongs.

Letter 8 – Delphinia picta: Picture-Winged Fly

Strange Fly
Can you tell me what this is? I noticed a lot of them flying around this weekend (May 7-8) where I live in Newport News, Virginia and tried looking them up on the net, but the closest I could find was a Pyrgotid Fly, mostly because of the wing shape and coloring. It is about 1/4 to 3/8 inch long. A local entomologist said it could be a seed maggot fly.
Harry

Hi Harry,
We contacted Eric Eaton for assistance with your photo. He writes: “The fly may be an Otitidae (aka Ulidiidae) species rather than a Tephritidae. I am just learning about the flies, though:-) Try the Systematic Entomology Laboratory at the Smithsonian, going to the Diptera pages. Also try Bugguide, as I have seen this critter there, again, in Otitidae.” We did some additional internet checking, and while we couldn’t locate your exact species we did find that this family is known as the Picture-Winged Flies as well as this information: “Larvae of most Picture-winged Flies feed on decaying vegetation while a few are root feeders.” There is also some confusion between the Platystomatid and Otitidid Flies as both are commonly called Picture-Winged Flies. Your fly is definitely not a Pergotid.

NOTE: Delphinia picta
(05/11/2005) Hi, I saw the photo submitted on 05/09/2005 by Harry of the picture-winged fly. I’ve photographed several of these in Atlanta. They were identified as Delphinia picta.
Bill DuPree
Atlanta, GA

Thanks for the assistance Bill.

Letter 9 – Possible Picture Winged Fly from The Congo

Subject: Unidentifiable fly
Location: Republic of Congo (Odzala NP)
July 7, 2016 1:42 am
For almost a year now I have been trying to identify this fly. Still, I have not found what species it is. My guess is that it belongs to the Ulidiidae, but I am not sure. Does anyone have an idea what species this fly could be? I photographed it in the Republic of the Congo
Signature: Daniel Nelson

Dear Daniel,
We agree that this could be a Picture Winged Fly in the family Ulidiidae, but we would seriously consider expanding the possibilities to include the superfamily Tephritoidea that includes Ulidiidae.  The perspective of your image, while quite artful, is not ideal for identification purposes if considered alone.  We once recall reading that four different views are helpful in identifying Robber Flies:  dorsal, lateral, head showing eyes and one other view that currently escapes our memory.  Alas, we cannot locate where we read that.  Furthermore, while quite pretty, many small flies do not command the same attention as large and showy butterflies, moths and beetles that are all much better represented on the internet.  Species from Africa are far less well documented on the internet than North American, Australian and British species.  We feel if you are only depending upon the internet, exact species identification based on this single image might not be possible.  With all that stated, we are posting your gorgeous image and we appeal to our readership to provide comments with any suggestions they may have.