Deerflies: here is what I know

I thought I might as well
macrophotograph them!

Aren't the eyes cool?!

Deer flies (also known as yellow flies, or stouts in Atlantic Canada) are flies in the genus Chrysops of the family Tabanidae that can be pests to cattle, horses, deer, (basically most mammals) and humans.

They live near bodies of water, hunkering down over winter. They complete their metamorphosis (see Purdue U. diagrams), from eggs, to larvae, to pupae, to adult, in a number of days. University website info tends to lump horse flies in with deer flies. Safe to say, it is about a week, but hardly matters. It is the adult that is the fierce one!

 The females require a blood meal for their eggs, but both males and females feed on nectar and plant juices for flight energy. They live near wetlands, requiring water. They can be merciless when you are swimming!

With wicked razor-sharp mandibles, injecting an anticoagulant into the wound, they suck for a few minutes. Ohio State U. says it is an hemorrhagic saliva.
The pain is horrible, with swelling around the open site. (I get a raised area of swelling the size of my palm. Heaven help you when you scratch it!) The flies suck the blood up from the wound for several minutes. "This process makes these flies potential mechanical vectors of such diseases as anthrax, tularemia, anaplasmosis, hog cholera, equine infectious anemia and filariasis." (*See U. Rhode Isl info page.)

Poor Bambi
she has five on her head.

Razor-sharp mandible rip at you

Deer flies and horse flies are also suspected of transmitting Lyme disease (New England Journal of Medicine 322:1752, 1990).

They are attracted to dark moving objects, as well as carbon dioxide. Bug repellants do not work on them. I often put on an oily lotion, Avon's Skin-so-soft, this reduces my tastiness, I think. It works for mosquitoes, as well. They do not come indoors, as mosquitoes do. Thankfully!

Dorah's face fur helps 

They love the heat, unlike mosquitoes, and thrive: swarming around their prey, landing on the back of your head preparing for attack.

Tred-not Deer Fly Patch, which is a non-chemical sticky patch for controlling horse and deer flies, works well to limit them.
They are odorless, adhesive patches, available in Crappy Tire, for example.

 The patches are 7.5 cm (3 inches) wide by 15 cm (6 inches) long, and are worn on the back of a baseball cap to trap and hold biting deer flies. The best thing I've found! They aren't cheap, two per package, and I can fill one in a 30 minutes garden weeding or walkabout, but they are well-worth it to

We weeded the garden again: 42 bodies
on the deerfly sticky paper.

me. The poor cats get so frustrated.
I wish I could stick them on for them! Their fur helps them, although Dorah got a bite on her nose the other day.

The trick is, what to do with them when you are done.
As I walk along, I can hear them buzzing! A weird sound. If I bring my cap indoors, the spiders feed on them. (That was a funny thing.)
I loathed hearing them buzz all night on the cap, so I drowned them. I fed them to my goldfish!
I decided to do some macrophotography, their eyes are amazing.