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

Subject: Massive black fly with distinct yellow spots
Location: Melkbosstrand, Cape Town, Western Cape, South Africa
January 5, 2014 4:25 am
This is the first time we have since this massive ‘fly’ – we took photos of him and thought it would be easy to identify him using our insect book, as he is so distinct, but it appears we are battling – real novices! Do you possibly know what type of fly it is? May not even be a fly…
Signature: Emma Theron

Male Horse Fly

Male Hippo Fly

Hi Emma,
Before we start our research, we will begin by telling you that the common family name for this fly in North America is Horse Fly, but in Australia, the same family is referred to as the March Flies, and that common name refers to a totally different family in North America.  We are going to use the scientific taxonomic name, which is Tabanidae.  It will be easier to begin our search of South African members that way.  We can also tell you that because of the close eye placement, this is a male Horse Fly and it is only the females that suck the blood from warm blooded mammals.  Horse Flies generally feed on livestock, but they can and do bite humans and the bite is somewhat painful.  Again, this is a male and only the females bite.
Continued research led us a matching photo and a very interesting answer. There was an identification request posted to ISpot and David Notton wrote in and identified it as a Hippo fly (
Tabanus biguttatus).  We found another image on Zandvlei Trust confirming the name Hippo Fly with the information:  “Adults attack large mammals such as hippos as blood suckers. Their larva feed on insect larva and tadpoles in mud pans.”  On South African Photographs, a photo of a female fly (space between the eyes) is identified as a Hippo Fly, Tabanus biguttatus, but the spotted abdomen is not visible.  Instead, the thoracic region is golden, leading us to believe there is pronounced sexual dimorphism in this species beyond the difference in the eyes which is characteristic of the entire family.  South African PHotographs indicates:  “These flies are huge – must be at least an inch in body length if not more. They attack large animals such as cattle and hippo’s driving them to spend the night underwater to avoid being bitten.” A similarly marked female is also pictured and identified on ISpotPHotos of both an identified female and unidentified male are pictured on the slide show of flies on Natures World of Wonder South Africa.  We would love to locate some reference that pictures both the male and female and discusses the distinctive differences between the coloration and markings of the sexes.

Thanks so much Daniel for the feedback and the good explanations and cross-references, I really appreciate it!
Kind Regards,
Emma

What's That Bug? does not endorse extermination

Subject: Loud & Fast; Scares the Dog
Location: Missouri, 60 miles from St Louis
September 30, 2013 2:31 am
Several of these show up around our house each spring-early fall. They will hover in place for a while, then take off really fast, zooming around for a while before suddenly stopping to hover in place. The hum/buzz of their wings is loud, my dog even refuses to go outside when he hears them. They fly very fast when they aren’t hovering (my grandpa started calling them ’bullet bugs’). I finally managed to catch one with a grocery bag so I could photograph it. If you can identify it, I’d love to know what this is that scares my dog (and if he has good reason to be scared!)
Signature: Cassie

Horse Fly

Horse Fly

Dear Cassie,
This is a Horse Fly in the family Tabanidae, and according to BugGuide:  “Females (but not males) suck vertebrate blood which they need to produce eggs.”  We are not certain of the species, but your individual resembles 
Tabanus calens which is pictured on BugGuide.  Your individual appears to be a male, which will not bite.  If you dog has had a bad experience with one or more females buzzing prior to biting, you dog might be remembering the experience.  Horse Flies generally feed on livestock, but when livestock is not available, other warm blooded prey, including humans, will suffice.

Thanks so much for that! I searched around for a while trying to find out what they are, but didn’t have luck. I’m usually better at identification when it comes to spiders (Love them so much).
Next time I get really good spider pics, I’ll be sharing them like I did my fishing spider before.

What's That Bug? does not endorse extermination

Subject: big fly
Location: catoctin mountains, maryland
September 9, 2013 10:42 am
I saw this fly outside on the table and ran to snap a picture. Is it a horse fly? It is about an inch long and entirely black.
Signature: jenny

Black Horse Fly

Black Horse Fly

Dear Jenny,
Yes this is a Horse Fly, and as you noted, it is black, so it makes sense that it is commonly called a Black Horse Fly, Tabanus atratus.  Your individual is a blood sucking female Black Horse Fly as evidenced by the space between her eyes.  The males of the species, like all Horse Flies, have much larger, more close-set eyes.  One can only speculate that such sexual dimorphism is due to mating and sexual reproduction.  We guess that male Horse Flies use their large eyes with 360 degree vision to spot females.

What's That Bug? does not endorse extermination

Subject: Silver & Black Insect
Location: Maryville, TN
July 22, 2013 11:29 am
This particular insect was found by a co-worker of mine today (07/22/2013) at approximately 1:30 p.m. in Maryville, Tennessee. To me, it seems to have many similarities to a horse fly but I have never seen one quite like this. Could you please help me indentify this insect? Thank you kindly.
Signature: Cody Moyers

Black Horse Fly

Male Black Horse Fly

Hi Cody,
This is a Horse Fly, and we believe it is a Black Horse Fly, Tabanus atratus.  This photo from BugGuide shows a similar coloration and we believe the eyes are reflecting back light, making them appear silvery.  The close-set eyes indicates this is a male.

What's That Bug? does not endorse extermination

Subject: Horse fly?
Location: NY lower Hudson Valley
July 12, 2013 11:23 am
Hello!
I found this large fly sunning itself on my deck umbrella this afternoon here in NY’s lower Hudson Valley. It’s body is shaped like a horse fly, but it’s markings do not match up with any horse fly pics that I’ve found. It is over an inch long in length. Is it a horse fly?
Signature: Don’t Bite Me

Horse Fly

Horse Fly

This certainly is a Horse Fly, and she does appear to be a female because of the space between her eyes.  Only female Horse Flies bite and feed on mammalian blood.  We believe we have correctly identified your Horse Fly as Tabanus trimaculatus based on photos posted to BugGuide.

What's That Bug? does not endorse extermination

Subject: Darth Vader bug
Location: north Illinois WI border
July 7, 2013 5:57 pm
This black insect died next to me . The insect is all black one inch long with a wingspan of 1 1/4 Inch. The eyes are the most interesting
Signature: jack Speer

Male Black Horse Fly

Male Black Horse Fly

Hi Jack,
This is a male Black Horse Fly,
Tabanus atratus, and this submission from 2010 also described it as looking like Darth Vader.  The eyes of male Horse Flies have no spacing between them, while the eyes of female Horse Flies have a noticeable space.  Only female Horse Flies suck the blood from warm blooded creatures, and they will bite humans if there is no livestock upon which to feed.  According to BugGuide:  “Females feed on mammalian blood, while males, which lack mandibles, feed on nectar and plant juices (Long 2001). This species especially prone to attack cattle and other livestock.”

What's That Bug? does not endorse extermination