Robber flies are fascinating insects known for their predatory behavior and large size, often mistaken for horse flies or other biting flies. Although fierce hunters in their own right, attacking various insects such as butterflies, wasps, and grasshoppers, they are not blood feeders and typically do not pose a threat to humans when left alone ncsu.edu.
However, it is important to note that some larger species of robber flies can inflict a painful bite if mishandled wisconsin horticulture. Despite the pain associated with their bite, robber flies are not venomous like certain snake bites cdc – meaning their bite will not deliver toxins into your system. As a rule of thumb, the best way to avoid any unpleasant interactions with robber flies is to observe from a safe distance and give them the respect they deserve as skilled predators in the insect world.
Robber Fly Bite: Is it Poisonous
Venom and Neurotoxins
Robber flies are known to be efficient predators, capturing and consuming other insects. However, their bite is not considered poisonous to humans. Although robber flies do utilize venom to paralyze their prey, this venom is not harmful to humans and does not contain neurotoxins.
Example:
- Robber flies use venom to immobilize insects such as bees and wasps, which they later consume.
Comparison with Other Insects
Comparing robber flies bites to other insects, it is evident that they pose a relatively low risk.
Comparison table:
| Insect | Bite Poisonous? |
|---|---|
| Robber Fly | No |
| Venomous Snake | Yes |
| Horse Fly | No, but can be painful |
While a venomous snake bite delivers venom containing harmful neurotoxins that can lead to severe symptoms or even death in humans, a robber fly bite is considered non-poisonous. Horse flies, in comparison, may deliver a painful bite, but their bite is also not poisonous.
Characteristics of robber fly bites:
- Painful, but not poisonous
- Venom utilized only for immobilizing their insect prey
Remember, despite their intimidating appearance and painful bite, robber flies do not inject venom or neurotoxins harmful to humans.
General Overview of Robber Flies
Appearance and Identification
Robber flies, belonging to the family Asilidae, are a diverse group of predatory insects with varying sizes and colors. They typically measure between 0.2 to 2 inches in length, with wings that often resemble those of other insects like bees and wasps 1. Some key features of robber flies include:
- Large, forward-facing eyes
- Strong, agile wings
- A long and pointed proboscis (tubelike mouth) used for attacking prey
For example, some robber fly species are brightly colored and can be mistaken for bees or wasps. This mimicry helps them ambush their prey with greater success.
Habitat and Distribution
Robber flies are found in various habitats across North America, particularly in areas with abundant vegetation and prey 2. They are commonly observed perched on exposed surfaces, waiting for an opportunity to snatch a passing insect. The distribution of robber fly species can vary depending on their preferred habitat and prey. Some examples of habitats that robber flies inhabit include:
- Forest edges
- Meadows
- Gardens
- Agricultural fields
In conclusion, robber flies are a fascinating and diverse group of predatory insects with unique appearances and wide distribution across North America. Their ability to mimic other insects like bees and wasps and their knack for ambushing prey make them an interesting subject for further study.
Feeding and Predation Habits
Hunting Techniques
Robber flies are skilled predators, using various techniques to capture their prey. One common method is the ambush attack, where they wait on perches and surprise their victims. Another tactic involves aerial pursuits, where robber flies actively chase down insects mid-flight.
Common Prey
Robber flies have a wide range of prey, including:
- Insects: They primarily feed on other insects, making them beneficial for controlling pest populations.
- Grasshoppers: These large, hopping insects are a common target for robber flies.
- Wasps: Despite their stingers, wasps can still fall victim to the ruthless robber fly.
- Bees: Even bees, capable of stinging in defense, are not immune to the robber fly’s attacks.
- Other flies: Smaller flies, such as house flies and fruit flies, may also be consumed by robber flies.
- Dragonflies: These agile, flying predators can become prey themselves when facing a hungry robber fly.
| Prey | Characteristics |
|---|---|
| Insects | Controlled pest populations, varied size and flying abilities |
| Grasshoppers | Large, hopping insects |
| Wasps | Possess stingers, aggressive when threatened |
| Bees | Can sting in defense, important pollinators |
| Other flies | Smaller, less agile insects |
| Dragonflies | Agile, flying predators |
Life Cycle and Development
Larval Stage
- Robber fly larvae live in the soil
- They feed on eggs, larvae, and soft-bodied insects
The larval stage of the robber fly begins as a tiny egg, hatching into a legless, worm-like creature. Living below ground, these larvae are predators, consuming a range of small insects and their eggs. Examples include beetle larvae, aphids, and mites. This stage lasts several months, with the larvae growing and molting into a larger form before pupation takes place.
Adult Stage
- Robber flies have a distinct, tapering abdomen
- Predatory with strong, bristled legs
In the adult stage, robber flies develop a tapering abdomen and strong, bristled legs to aid in prey capture. These predators are known for their aggressive nature, attacking a wide variety of insects such as butterflies, wasps, beetles, and other flies. They do have sharp mouthparts and can deliver a painful bite, but it is not poisonous. Instead, the adult robber fly injects its prey with a saliva containing enzymes that paralyze and digest the victim’s tissue.
Robber Fly Bite Comparison Table
| Characteristic | Robber Fly Bite | Other Insect Bites |
|---|---|---|
| Painful | Yes | Varies |
| Poisonous | No | Some |
| Bite Purpose | Prey capture | Varies |
| Biting Humans | Rare, only when mishandled | Some bite, some sting, some don’t interact with humans |
In summary, the life cycle of the robber fly consists of a soil-dwelling larval stage, where they consume various small insects and their eggs, followed by an adult stage, where they are aggressive predators with strong, bristled legs and a tapering abdomen. Although robber flies can deliver a painful bite, it is not poisonous and is solely used for prey capture.
Importance and Benefits
Robber flies are a beneficial group of insects. They contribute greatly to the ecosystem, particularly in grasslands.
- Predatory nature: They are fierce predators, preying on a variety of insects, such as bees, wasps, dragonflies, spiders, and beetles.
- Biological control: Their predatory nature helps maintain a balance within the ecosystem, by keeping the population of pests in check.
Robber flies come in various colors and sizes, ranging from 0.2 to 2 inches. Some even mimic other insects like bumblebees and wasps. This makes them efficient in capturing prey.
Their bite, however, is not considered poisonous to humans. These predators inject venomous saliva into their prey, but its effects on humans are generally very minimal. Biting humans is typically not a concern, as they only bite if mishandled or threatened.
In conclusion, robber flies play a crucial role in maintaining the balance in ecosystems like grasslands. They are beneficial to the environment as they help reduce the population of pests and other harmful insects. However, they are not a threat to humans in terms of poisonous bites, making them a valuable part of our natural surroundings.
Symptoms and Treatment of Robber Fly Bites
Symptoms and Allergic Reactions
Robber flies are not poisonous, but their bite can be painful due to their strong mouthparts used for capturing prey. Some individuals may experience itching and swelling at the bite site. In rare cases, a person may have an allergic reaction to the bite, potentially causing symptoms such as:
- Hives
- Nausea
- Swollen lymph nodes
Treatment Options
Treatment for a robber fly bite primarily involves managing the pain and itching. Some options include:
- Applying a cold compress to reduce swelling
- Using over-the-counter antihistamines to alleviate itching
In case of an infection, a doctor may prescribe antibiotics. If you experience an allergic reaction, it’s essential to seek medical attention immediately.
To summarize, a robber fly bite can be painful and cause itching, swelling, and in rare cases, an allergic reaction. Treatment involves managing symptoms with cold compresses, antihistamines, and in some cases, antibiotics to fight infection.
Comparison with Other Biting Insects
Deer Flies and Tularemia
Deer flies are known for their painful bites, but they also have the potential to transmit tularemia, or rabbit fever. Some key points about deer flies and tularemia include:
- Deer flies are biting flies
- They can transmit the tularemia bacteria to humans
- Tularemia symptoms can range from mild to severe
Sand Flies and Leishmaniasis
Sand flies can transmit a parasitic disease called leishmaniasis. Here are a few aspects of sand flies and their role in spreading leishmaniasis:
- Sand flies are tiny biting insects
- They are responsible for transmitting leishmaniasis parasites
- Leishmaniasis can have varying symptoms and severity levels
Black Flies
Black flies, also known as buffalo gnats, are another type of biting insect. They do not transmit diseases like deer flies or sand flies, but their bites can be painful and cause irritation. Black fly bites can lead to:
- Painful swelling and itching
- Red welts on the skin
Biting Midges
Biting midges, also known as no-see-ums, are tiny insects that can cause discomfort when they bite humans. Here are some characteristics of biting midges:
- Biting midges are small, often less than 1/8 inch long
- Their bites can be painful and itchy
Stable Flies
Stable flies are another kind of biting insect that can cause annoyance and discomfort. They are similar to house flies but have a painful bite. Some key points about stable flies include:
- They are similar in size and appearance to house flies
- Stable fly bites can cause pain and irritation
Comparing these biting insects with the robber fly, also known as the assassin fly, they all differ in their behavior and impact on humans. While the robber fly does use venomous saliva to immobilize its prey (bees, wasps, dragonflies, spiders, beetles, and other flies), it is not considered harmful to humans unless mishandled (Smithsonian Institution). Therefore, robber fly bites do not pose the same risks as bites from other biting insects mentioned above.
Physical Characteristics
Robber flies are known for their unique physical features. They possess a prominent proboscis, which is a sharp tube or beak used for feeding. These insects also have large, widely-spaced compound eyes that aid in spotting their prey.
Another distinctive feature is the mystax, a patch of hair located on the robber fly’s face. This mystax helps protect them from potential retaliation by their prey. Moreover, they have antennae that assist in sensing their surroundings.
Here’s a quick comparison of some key robber fly features:
| Feature | Function |
|---|---|
| Proboscis | Used for feeding |
| Compound eyes | Aids in spotting prey |
| Mystax | Protects the face from prey retaliation |
| Antennae | Helps in sensing the environment |
When considering robber fly bites, it is important to know that these insects are not poisonous. While they are fierce predators, their venomous saliva is only used to immobilize their prey, such as bees, wasps, and other insects. A robber fly is unlikely to bite humans, and if it does so, it is usually a result of being mishandled. So, even though they have a fearsome appearance, robber flies are not considered to be a threat to humans.
Footnotes
39 Comments. Leave new
I found one of these while was at work a few years ago, it was just laying on the footpath and looked as if had only just died. I couldn’t believe how big it was and had never seen any thing like it before so i picked it up and took it home. I still have it.
If you ever take a photo of it, we would love to post it. Please title the subject line of the email “Giant Yellow Robber Fly from Australia” and it will get our attention.
Hello Bugman
I took a few pics of one of these beautiful creatures:-)
Sadly I only have a camera in my mobile phone but tried to get as close as I could:-) This was just after I noticed he had grabbed a wasp in the air and then landed to have his lunch.
I am having a hard time loading the pic to my comment.. so will email them to you:-)
Rob
Try using our standard submission form: https://www.whatsthatbug.com/ask-whats-that-bug/
I have a property about a hour out of Perth and I had one fly past me. the thing was huge and at first I didn’t take much notice but then the next day I saw it again and then the day after and so on before I knew it we now have about 4 living around our house. I have only recently decided to study them because of the growing population. they let you get very close but its scary when they take off because you don’t know if its going to bite you or not. so I can get photos if you want.
We would love photos. Please use our standard form and label the title Robber Flies from Australia.
cught one in Bridgetown, WA last week
(can send pics if sombody is interested)
We would love to get photos. Please use our standard form: https://www.whatsthatbug.com/ask-whats-that-bug/
cught one in Bridgetown, WA last week
(can send pics if sombody is interested)
We found one of these Robber Flies at our stable today, been searching all over for an identification for him! We see them often, located in benson Az, and they are often confused on fly by’s with our tarantula wasps, except their body shape is quite different if you get that good a look at them!
We would love a more recent photo if you are able to get one. Please use our standard submission form and the subject line “Mexican Robber Fly from Arizona” if you send an image.
It’s a Giant Yellow Robber Fly. I captured one today in Williams, Western Australia but at first could only find reference to them being in QLD and SA. I have since found a few reports of them being sighted in WA so they are definitely here! 🙂 The one I captured looks exactly like this. It is huge and has a huge giant golden yellow abdomen with “serrated” edges. It makes a very loud buzzing sound when it flies. When at rest it looks completely black with it’s black wings neatly overlapping and folded over top of it’s abdomen. When in flight the abdomen is very visable (alarmingly so). It is a very impressive insect and scared all of our kids as they thought it was a giant wasp. The photos I got were not very good as they were taken while it was inside a clear bucket… as soon as I released it, it flew away very quickly. There are some excellent photos of them here: http://www.brisbaneinsects.com/brisbane_robbers/LargeRobberFly.htm
Thanks for the comment and the information about the range of the Giant Yellow Robber Fly. We also have this posting of a Giant Yellow Robber Fly our archives that shows the abdomen.
I see one on my farm near Vryburg North West South Africa about n week agou.
Good day
I Live in Kloof in Kwazulu Natal in South Africa , just wanted to say i have seen the same type of Fly/Bee and it was Big and Hairy and 100% certain its the same or the giant in this species .
Kind regards
Adam
Good day
I Live in Kloof in Kwazulu Natal in South Africa , just wanted to say i have seen the same type of Fly/Bee and it was Big and Hairy and 100% certain its the same or the giant in this species .
Kind regards
Adam
I have a problem with theses Carpenter bee robber fly boring into my exposed roof trusses in my house in Pretoria, South Africa. The exposed ends were treated with creosote, but obviously not recently as it didn’t stop them penetrating. Any advise please as I need to get rid of them?
We do not provide extermination advice.
we have found a Giant Yellow Robber Fly in our garden on a Diosma Bush in Geelong ive never seen anything like it before. Are thay common in this part of the country?
I live in South Texas. This insect was in my yard this morning.
I thought it was a bee but could not understand why it was black and white. Then I noticed it was more fly like. It was struggling to get out of my watered lawn. I put a large leaf under it, raised it up, and it flew away. We get “African Dust”. Could this insect have traveled all the way from Africa or be something entirely different? I know it lookef just like the photo above.
We suspect you witnessed a local species, possibly the Belzebul Bee Killer.
I live in South Texas. This insect was in my yard this morning.
I thought it was a bee but could not understand why it was black and white. Then I noticed it was more fly like. It was struggling to get out of my watered lawn. I put a large leaf under it, raised it up, and it flew away. We get “African Dust”. Could this insect have traveled all the way from Africa or be something entirely different? I know it lookef just like the photo above.
This appears to be the thing terrorising my wife and kid the last few days at our residence in Cunderdin WA.
I have been trying to research and find out what it might be over the past few weeks, but hadn’t had much luck till I saw this post.
It’s a massive insect that eats bees and large hornets for breakfast!
It usually sits up high in the backyard waiting for the moment to descend on a unsuspecting insect.
When they fly, the wings uncover to reveal a bright orange/yellow abdomen.
That sounds like the behavior of a Robber Fly.
This appears to be the thing terrorising my wife and kid the last few days at our residence in Cunderdin WA.
I have been trying to research and find out what it might be over the past few weeks, but hadn’t had much luck till I saw this post.
It’s a massive insect that eats bees and large hornets for breakfast!
It usually sits up high in the backyard waiting for the moment to descend on a unsuspecting insect.
When they fly, the wings uncover to reveal a bright orange/yellow abdomen.
We have returned from the beach in lower Mozambique where both these flies and carpenter bees were in abundance. They often try to land on the surfers and it’s comical to see them trying to wave them away. They are very persistent though… it doesn’t matter how many times you wave them away they will always come back. They also seem to be attracted to very bright colors… i had a red air lounger on the beach and they were constantly
resting on it. They look like they could have a nasty bite or sting… can anyone confirm this ?
We have returned from the beach in lower Mozambique where both these flies and carpenter bees were in abundance. They often try to land on the surfers and it’s comical to see them trying to wave them away. They are very persistent though… it doesn’t matter how many times you wave them away they will always come back. They also seem to be attracted to very bright colors… i had a red air lounger on the beach and they were constantly
resting on it. They look like they could have a nasty bite or sting… can anyone confirm this ?
.An Hyperechia imitator somehow landed on my hand near Kirstenbosch. Very large, pure black – no brown band on the thorax. After examining it I released it into a bush – it did not attempt to fly away – was sluggish.. When I retrieved it to show to someone it “stung” me. It was not particularly painful. I have been stung many times by wasps/bees and have suffered an anaphylactic shock after being stung (unsolicited) by a vespidae species (not identified).
I presume it was a “bite”. It itched considerably for a couple of days thereafter.
.An Hyperechia imitator somehow landed on my hand near Kirstenbosch. Very large, pure black – no brown band on the thorax. After examining it I released it into a bush – it did not attempt to fly away – was sluggish.. When I retrieved it to show to someone it “stung” me. It was not particularly painful. I have been stung many times by wasps/bees and have suffered an anaphylactic shock after being stung (unsolicited) by a vespidae species (not identified).
I presume it was a “bite”. It itched considerably for a couple of days thereafter.
Hi, I have a couple of photo’s of these insects alive in the wild,if you send a reply email I would be happy to share these pics.
Kind Regards
Bazil J
We would love to post your images. Please submit them using the Ask What’s That Bug? link on our site.
Hi, I have a couple of photo’s of these insects alive in the wild,if you send a reply email I would be happy to share these pics.
Kind Regards
Bazil J
I was just researching this and read your story. I too use tea tree products and was pursued and attacked by robber flys on my walk here outside of houston tx last night. I managed to kill a couple of them as they bit my arms and legs. I started running and they pursued me for about 50 yards or so and then gave up. I’ve never experienced anything like that before….
Good day I would just like to find out what can happen to a person if the carpenter bee robber fly bites you. We had a incident where someting bit my son that was black and flew away he couldn’t see how it looks was to fast he lost is index finger from te bite
I am from Tyler, TX and just a few days ago I was bit by a fly just like this! It was in Flint, TX, which is just outside of Tyler. The abdomen was slender, just like this Robber Fly. I definitely saw it biting me, as I had to swat it away after I felt it. I’ve been bit by horse flies before, my entire life! This bite hurt much worse (I thought I was being stung by a wasp or bit by a spider!) Days later, it was raised and itchy, like a bad mosquito bite.
The only other thing I remember about it is the way it flew away. It moved almost like a hummingbird (fast and agile!) I think it flew underneath our wooden deck, between the boards. It bit me on the inside of my ankle, so it’s possible it came from under the deck to begin with.
I did some research and found that Robber Flies are predators (not blood-sucking parasites) but I’m confident that it was a fly just like the one in this picture, and it wasn’t provoked (unless maybe it was under the deck and we disturbed it?) Are these flies aggressive?
I am from Tyler, TX and just a few days ago I was bit by a fly just like this! It was in Flint, TX, which is just outside of Tyler. The abdomen was slender, just like this Robber Fly. I definitely saw it biting me, as I had to swat it away after I felt it. I’ve been bit by horse flies before, my entire life! This bite hurt much worse (I thought I was being stung by a wasp or bit by a spider!) Days later, it was raised and itchy, like a bad mosquito bite.
The only other thing I remember about it is the way it flew away. It moved almost like a hummingbird (fast and agile!) I think it flew underneath our wooden deck, between the boards. It bit me on the inside of my ankle, so it’s possible it came from under the deck to begin with.
I did some research and found that Robber Flies are predators (not blood-sucking parasites) but I’m confident that it was a fly just like the one in this picture, and it wasn’t provoked (unless maybe it was under the deck and we disturbed it?) Are these flies aggressive?
I saw one in Sierra Vista eating those big wasps we get at the end of the year. It was hugeeee
got a photo of green eyed robber fly..just researching..
I was working night shift on a buffer (when landline phones still existed). One of these bit me so hard I dropped the handset which roichocheted and flew past my head about 40 mph. I knew what bit me because it casually flew a few feet and landed on the wall next to me. I always called these things horsefly’s ever since. They do bite, maybe the loud vibrating machine triggered it.