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
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 ISpot. PHotos 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!