Deer Fly (Female) - Chrysops vittatus

Deer flies are incredibly annoying pests with a painful bite. Females have serrated, knife-like mouthparts that they use to slice and stab their victims, repeatedly. Then, they feed on the blood pool that is created using a sponge-like portion of their mouthparts. The males lack these specialized mouthparts and only feed on plant nectar.

Habitat: Rural garden

comments (12)

Ferdy Christant

Lion

Really wonderful post! Great photo, new species, and wonderful text.
I once heard that horse flies fly 10 times faster than a common house fly. I wonder if the same is true for deer flies. Posted 5 years ago
1. Christine Young
  
  Lion
  
  Horse and deer flies are both in the family Tabanidae, with horse flies usually being a bit larger than deer flies. There's a species in Maine that is about 35 mm long and it's referred to locally as the "moose fly" because of its size...As for speed, they are both really fast - among the fastest flying insects, in fact. And, they are both incredibly annoying as they like to ping off your head and inflict painful bites. Posted 5 years ago
2. 1. Ferdy Christant
    
    Lion
    
    Luckily, I rarely encounter them. I do have a lady friend that is into horse riding who says they are the most annoying thing ever. The flies always go for the horse's belly, where the horse can't do anything about it.
    
    The most annoying fly I've ever encountered is this:
    https://en.wikipedia.org/wiki/Tsetse_fly
    
    In Tanzania, we drove through an area with clouds of them. At any time, there were dozens to possibly hundreds in our open jeep. Most near our feet, repeatedly biting us. Amazingly, they bite straight through thick hiking socks.
    
    We got increasingly furious sitting through this but had no way to run, unless you want to get out of the jeep and enjoy a lovely hike on the Serengeti. Amidst the tall grasses that could be hiding anything. Posted 5 years ago
  2. 1. Christine Young
      
      Lion
      
      Oh, tsetse flies! They have such an odd reproductive biology. The females nurse the larvae in utero and give birth to live young. She only has one baby (maggot) at a time, but before birth, it will weigh nearly as much as she does! The females also pass on bacteria to her young that will establish themselves in the midgut and are necessary to synthesize certain nutrients so the young have a healthy immune system. Posted 5 years ago, modified 5 years ago
    2. 1. Christine Young
        
        Lion
        
        I encounter deer flies quite a bit in the summer, but not many horse flies. I despise them though and frequently get in shouting matches with them. One interesting thing - deer flies (probably horse flies too) and tsetse flies are attracted to the color blue. Posted 5 years ago
      2. Ferdy Christant
        
        Lion
        
        Yes, good point about the blue. In the area we drove through, there were blue flags attached to trees to distract them from biting people. Which didn't really work in this case. I don't recall the exact number but I believe that if you're bitten by these flies for an uninterrupted amount of days, you may develop some kind of sleeping disease. Tourists are fine as they won't stay that long but it's a serious danger for locals.
        
        Thanks for that reproduction information, it's bizarre. I figured a species like the tsetse would be of your interest given your study. Posted 5 years ago, modified 5 years ago
        
        Christine Young
        
        Lion
        
        Ha, you're right. I did study tsetse flies, but not in too much depth.
        
        The blue flags are actually traps of a sort. They are covered in insecticide, which kills any tsetse flies that land on the flag. It's a cheap method of control and fairly effective, but the flags do have to be replaced every so often.
        
        It only takes a bite from one fly to become infected with the parasite that causes sleeping sickness. BUT, few tsetse flies carry the parasites (Trypanosoma sp.) and the disease is thankfully becoming less common. The disease is fatal, but can be treated if caught early, which it often isn't. I don't think there is a vaccine yet, but there has been talk for years about attempting to develop one that targets antigens, I think. I don't know exactly as it's been a few years since my working days ;P.
        
        Posted 5 years ago
        
        Christine Young
        
        Lion
        
        Oh, and a scary thing about sleeping sickness is that it can be transmitted through blood transfusions, sexual contact, and from mother-to-child! Posted 5 years ago
        
        Ferdy Christant
        
        Lion
        
        I did not know that about a single bite, I think I misread the information I got back then. My assumption was that if bitten many times across several days, some "dose" builds up and comes towards a tipping point.
        
        In terms of an infection, in hindsight that makes very little sense. I guess what they were trying to say is that it's a lottery. The odds of one having the disease and biting you simply become ever worse as exposure is longer. Posted 5 years ago, modified 5 years ago
        
        Christine Young
        
        Lion
        
        Yes, exactly. The longer you're in the environment, the more flies are likely to bite you, which increases the chances that one of those flies will be infected. Posted 5 years ago
        
        Ferdy Christant
        
        Lion
        
        Well, ignorance is bliss. We were feeling so safe, knowing you'll only get this disease after a few weeks of bites.
        
        Except that it was entirely wrong. Posted 5 years ago
        
        Christine Young
        
        Lion
        
        Indeed - at least you weren't stressing about trypanosomiasis while you were there. The stress could have reduced your immune response and made you more susceptible to illness. Posted 5 years ago