Dad Used to Call Them…
“Mayflies.” We all know those large, black flies that zoom around your head to snack on you in the summertime. These pests can often be found in fields and around sources of water, such as ponds and rivers. Though I grew up calling them mayflies, they are actually known as deer flies. Interestingly enough, they just so happen to emerge around the same time as the mayfly. This year I noticed the first one on exactly May 1st!
The mayfly is actually part of the dragonfly family and spends its life cycle in and around water, pretty much avoiding humans altogether. In fact, they are a large source of food for fish! They are used for bait, especially for bass, who eat their nymphs (babies) that develop in the water. So, my family has been mistakenly giving them a bad name, mayflies are great, it’s the deer fly that isn’t.
Deer flies emerge in May and generally are around until early September. Last year, it was exactly September 9th when I observed the last one. I hate them with every fiber of my being, even more than I hate fire ants. Here are some fast facts about these awful creatures:
Deer flies lay between 100 and 800 eggs in batches on vegetation near water or dampness, and emerge as adults in late spring and summer.
While male deer flies collect pollen, female deer flies feed on blood, which they require to produce eggs. Females feed primarily on mammals.
They are attracted to prey by sight, smell, or the detection of carbon dioxide. Other attractants are body heat, movement, dark colors, and lights in the night.
They are active under direct sunshine and hours when the temperature is above 71° F. When feeding, the females use scissor-like mandibles and maxillae to make a cross-shaped incision and then lap up the blood.
Parasites and diseases transmitted by the deer fly include tularemia, anthrax, anaplasmosis, equine infectious anemia, hog cholera, and filariasis. DEET is not an effective repellent against these creatures.
To summarize, deer flies are attracted to their prey by various factors, including carbon dioxide, body heat, movement, shiny surfaces, and dark colors. So how do we combat them? Make sure to wear light colors and a hat, and minimize time spent outside when the temperature is above 71 degrees. Other than that, we’ll just have to wait until September 9th to be safe!
