Currently viewing the category: "Flies"
What's That Bug? does not endorse extermination

Subject:  Flies
Geographic location of the bug:  Cootamundra, NSW. Australia
Date: 02/20/2018
Time: 12:55 AM EDT
Your letter to the bugman:  Wanting to know what sort of fly this is? Thank you.
How you want your letter signed:  Graham

Horse Fly or Bee Fly???

Dear Graham,
Our initial thought is this must be a Horse Fly (called March Flies in Australia) from the family Tabanidae, but there are no similar looking images on the Brisbane Insects site.  The white edge on the compound eye is a trait found in several Bee Flies on the Brisbane Insect site that share that trait.  We are going to request assistance from our readership with this identification.

What's That Bug? does not endorse extermination

Subject:  March fly?
Geographic location of the bug:  Tampa bay fl
Date: 02/19/2018
Time: 04:17 PM EDT
Your letter to the bugman:  We were on the beach and everyone assumed it was a love bug but it was solid black the size of  my Fingernail.   They were in a swarm landing on people some people were covered in about 20 of them .
How you want your letter signed:  Nicole

March Fly

Dear Nicole,
This is indeed a female March Fly.  The Love Bugs that are well known in parts of Florida and the South are also March Flies, but Love Bugs,
Plecia nearctica, which are pictured on BugGuide, are red and black.  So, all Love Bugs are March Flies, but there are many species of March Flies that are not Love Bugs.

What's That Bug? does not endorse extermination

Subject:  What is this?
Geographic location of the bug:  Caribbean side of Costa Rica
Date: 02/15/2018
Time: 09:18 AM EDT
Your letter to the bugman:  This bug is about an inch and a half long. The body is orange-ish.  It came out at night but was still here in the morning.
How you want your letter signed:  Sherry Lidstone

Male Timber Fly

Dear Sherry,
This is one beautiful fly, and the large eyes indicate it is a male Fly.  Our best guess is that it might be a male Horse Fly, but we have never seen any images of Horse Flies with such unusual markings.  Perhaps one of our readers will be able to assist us with a proper identification.

Thanks to Cesar Crash, we now know that this is a male Timber Fly in the family Pantophthalmidae.  We have images of a female Timber Fly in our archives.

What's That Bug? does not endorse extermination

Subject:  Bug in freshwater fountain
Geographic location of the bug:  Victoria Australia
Date: 02/07/2018
Time: 05:00 PM EDT
Your letter to the bugman:  Hello,
We have a fresh water pond with running water along a pot. This is at the top of the pot and these hanging in the water. Fixed by their back end, hanging down, and with two antennae like.
They are 6-8mm in length and in a group of about 20!
They seem the wrong shape for the mosquito larvae I have seen, but not sure if they are!
Thanks for your help
How you want your letter signed:  Julien

Black Fly Larvae

Dear Julian,
Your query has us quite intrigued.  We concur that these are NOT Mosquito Larvae.  Mosquito Larvae breathe through a siphon and they congregate at the surface of generally stagnant water.  We suspect these are larvae and that they are members of the Fly order Diptera.  We also suspect that in their natural environment, they affix themselves to rocks in flowing streams.  We located this image on SlideShare of some aquatic Dipteran larvae and several resemble your individuals.  At this point, we suspect this might be a member of the Black Fly family Simulidae, and according to BugGuide:  “Larva: brown, gray, or black with light brown head; body cylindrical, somewhat club-shaped; head with prominent pair of mouth brushes used for filtering food from the water” and “larvae develop in running water of all types, from the smallest seepages and streams to the largest rivers and waterfalls; they attach themselves to underwater rocks and other objects by means of small hooklets in a sucker-like disc at the tip of the abdomen.”  Bug Eric has some very similar looking images.  Though they are not Mosquitoes, female Black Flies are blood suckers.  According to BugGuide:  “Black flies attack most severely about sunrise and at sunset — either massively and viciously or in such small numbers that they are scarcely noticeable. They bite painlessly so that you may not be aware of having been attacked until small droplets of blood start oozing from your skin. Black flies often crawl into your hairline or through openings in your clothes before they bite you. Therefore, the bites are usually behind your ears, around your neck and beltline, and on the lower parts of your legs. A typical bite consists of a round, pink, itchy swollen area, with a droplet of fresh or dried blood at the center. When the blood is rubbed away, a minute subcutaneous hemorrhage is visible. This hemorrhage and the surrounding pink area become diffuse and larger, and then disappear within a few days. Itching may continue intermittently for weeks, whenever the bitten area is rubbed. Scratching may cause severe secondary skin infections. Toxins injected during an extended severe attack can cause a general illness sometimes called black-fly fever, characterized by headache, fever, nausea, and swollen, painful neck glands. Attacks occur throughout late spring and early summer (sometimes throughout the summer). (Fredeen 1973)  often ranked third worldwide among arthropods in importance as disease vectors, but only ~10-20% of the world’s spp. are pests of humans/livestock.” According to Atlas of Living Australia:  “Most black flies gain nourishment by feeding on the blood of mammals, including humans, although the males feed mainly on nectar.”

Black Fly Larvae

Dear Daniel,
Thank you so much for looking into that!! Your suggestion and pictures are very convincing. We do have these flies around as well. I have taken pictures again and I think that we can see the one in their cocoon on the bottom and the other one on top!
Your site is a great help!
Best wishes

Black Fly larvae and pupae

What's That Bug? does not endorse extermination

Subject:  robber fly identification
Geographic location of the bug:  New Jersey
Date: 02/04/2018
Time: 01:18 PM EDT
Your letter to the bugman:  Greetings:
I’m having trouble identifying Robber Flies. I’ve uploaded 2 fairly similar pictures (more pictures can be found at and respectively). The first has been IDed as a  Promachus hinei and the other as a Red-footed Cannibalfly (Promachus rufipes). Are these IDs correct and these are different species? If so, what’s a good way to distinguish them? And are there any other similar Robber Flies I’m likely to run into in New Jersey?
P.S. I think Robber Flies are interesting, but don’t really know much about them except that they’re considered fairly tough predators in the arthropod world.
How you want your letter signed:  Baffled By Robberflies

Red Footed Cannibalfly

Dear Baffled,
Sometimes it is not possible to identify a species conclusively from a photograph alone, and the Giant Robber Flies in the genus
Promachus can be a challenge.  We are somewhat inclined to doubt the accuracy of the individual identified as Promachus hinei on iNaturalist because BugGuide lists the range of the species as being considerably west of New Jersey with Ohio being the easternmost sighting.  Because of the proximity of your two sightings in both location and time, we would be most inclined to suppose them to be the same species, and the Red Footed Cannibalfly is a likely possibility, especially since both of your individuals have red “feet” and the physical description on Encyclopedia of Life states:  “Adults are 28 – 35 mm long. Typical of robberflies, the eyes are large and separated by a deep trough on top of the head. The body is covered in yellow bristles, particularly on the head and abdomen. The legs are black, except for orange tibia and pulvilli. As with other members of the genus Promachus, this species has sharp claws and an abdomen that extends beyond their folded wings. ”  We apologize for not being able to provide a conclusive identification and we suspect that if actual specimens were to be identified by a dipterist specializing in Robber Flies, many of the individuals identified on our site as Red Footed Cannibalflies might actually be members of a similar looking species in the same genus.  Like many other large Robber Flies, Red Footed Cannibalflies and other members of the genus are able to take large prey, often stinging wasps and bees, on the wing.  Thank you for becoming a Patreon member and helping to support the free service we are able to supply on the World Wide Web.

Red Footed Cannibalfly

Thanks for telling me what you know about these guys. I suspect that I’m going to have this problem with a lot of insects; too many similar-looking relatives. (I was kind of hoping you’d be able to tell me that no other species that looks like the Red-footed Cannibalfly lives in NJ.)
Hi again John,
We located this comment on BugGuide “As I understand it, there are three ‘tiger-striped’ species of 
Promachus in the eastern U.S., with P. hinei being the most common in the central U.S. It is distinguished from the more southern P. rufipes by the reddish rather than black femora and from the more northern P. vertebratus by the larger dark areas dorsally on the abdominal segments and distinctly contrasting two-toned legs.”  That supports our supposition that both of your individuals are Red Footed Cannibalflies, Promachus rufipes.
Greetings Daniel:
That was helpful. Just for due diligence, I then checked out BugGuide’s info on Promachus vertebratus to see if that could be a good candidate for my Robber Flies. And it really isn’t; P. vertebratus’s range is typically outside NJ, and it’s green or red eyes aren’t a match for any of my Robber Flies.

I’m cautiously optimistic that the Red-footed Cannibalfly is what I’m seeing.

Thanks again.


And we agree, so we are changing the subject line of the posting to reflect that.

What's That Bug? does not endorse extermination

Subject:  Horsefly or Drone?
Geographic location of the bug:  Chile central
Date: 01/06/2018
Time: 06:14 AM EDT
Your letter to the bugman:  This little fellow was spotted on a tree. Ive never seen this kind before in this region, we have gray horse flies and Scapia Lata in the south.  Seeing it from distance it looked like a queen bee or drone (because of the size), a “bumblebee male” someone suggested, but I believe is a smartly bee-colored horsefly. Can you identify the bug ?
How you want your letter signed:  Mr.

Robber Fly

Dear Mr.,
This is one impressive looking female, predatory Robber Fly in the family Asilidae.  We were unable to locate any Chilean individuals that resemble your submission, but it does remind us of the North American Bee Killers.  Large Robber Flies like this one often take large winged prey, including wasps and bees, on the wing.

Thank you very much!!! Your identification has been confirmed by a local entomologist, this specimen corresponds to Obelophorus landbecki species, apparently a stealthy hunter from the arid Chilean central zone.

Thanks so much for writing back with a species identification.  We did locate an image on the Pierre.Comte.Over blog as well as an image on Insectos de Chile, and in both instances they are images of mounted specimens.  We could not find any images online of living specimens, which makes the posting of your contribution to our site unique.

What's That Bug? does not endorse extermination