Drought-fearing Arkansans long for rain as summer reduces lush green to tan tinder.
But a dry summer has one excellent advantage over a damp one: fewer horseflies.
Horseflies are large flies whose biting females make life miserable for horses (duh) and other livestock. But as one exasperated poster commented on the Arkansashunting.net chat board in June, “Somebody thought by naming them horseflies they would leave us alone.
It didn’t work.”
They (and their cousin the deerfly) bite people, too. They are the stout little B-52s that drone at you, Mr. Hunter/ Hiker/Runner/Four-wheeling ATV’er - anybody - when you’re minding your own business along a trail beside a creek, pond, marsh, ditch, puddle.
ZZrrrr, ZZrrrr, they circle and circle and circle. So you go faster, but still, ZZrrrr, ZZrrrr.
Stupid horsefly. What on earth does she want?
What do you think she wants? She bumps into you and - hey! Ouch!
These relentless females were the loudest of the biting things that kept Conway resident Charlie Dunn flapping a spare handkerchief around his head March 19 to July 3, as he hiked 1,239.7 miles from Georgia to Pennsylvania on the Appalachian Trail.
“I would say it’s more dread than anything else because you know they are coming as soon as the coolness of the morning wears off,” Dunn recalls, safely indoors at home in Conway.
“And, they are incessant. They are not deterred by you swatting at them. They just dodge your hand and make another pass at your bare skin. In my case it’s the skin on top of my head that does not have a protective covering of hair.”
Peak attack times vary from species to species, but the longer you stay outdoors, the more likely they will come looking for you. Which means horses and cows are sitting ducks.
Alvin Draper owns horses and also East End Hardware in Saline County, and his animals suffer from horseflies in the summer. “There’s not really a whole you can do until they die,” Draper says.
He has his preferred brand of fly spray, and his customers have tried others, some of which say on the label that they last up to 14 days. “When I feed, I spray a fogger. Before I ride, I spray [the horses] down … just to get them away.”
Such products act as repellents rather than insecticides because the flies’ contact with their targets is too brief to poison them properly.
In Draper’s experience, however, the residue comes off when horses sweat. “It’s not going to last as long as they say it will,” he said. Which is not good, because horsefly bites are very painful, and even a mild-mannered horse could freak out when startled by pain.
If you keep horses or cattle, you know these flies come in different colors and sizes.
Entomologists have identified more than 300 species in North America. Arkansas is home to several, and the most troublesome are listed here for the benefit of those who find comfort in saying the names of all earthly creatures. According to “Arthropod Pests of Equines,” a publication of the University of Arkansas Division of Agriculture’s Cooperative Extension Service, we have reason to dislike:
Black flies (Tabanus atratus Fabricius)
Black-striped flies (Hybomitra lasiophthalma Macquart)
Lined flies (Tabanus lineola Fabricius)
Autumn flies (Tabanus sulcifrons Macquart)
Also we have the [insert your preferred cuss word here] deerflies, which are smaller - only a quarter to three-eighths of an inch long, while horseflies range from one-half to1¼ inches long. Pause here to imagine a biting fly that’s 1¼ inches long.
John Hopkins, UA Extension Service urban entomologist, says horseflies primarily feed on large animals, not people. But “if you’re on the outskirts of town and you keep horses and livestock or you live near pasture where cows are,” horseflies aren’t opposed to biting you, too.
“You may have a horsefly that hangs around a swimming pool and may bite somebody, and it’s a painful bite,” he says. “You can generally see them all summer long.”
All these biters belong to the family Tabanidae, and so we can refer to them in general as “tabanids.” And here is what most tabanids have in common: The females want your blood.
A FLY’S LIFE
MaryAnne Stansbury, park interpreter at Pinnacle Mountain State Park, is grateful that tabanids have been leaving her alone lately. They were “bad in the spring and much worse than last year,” she says, possibly because spring 2013 saw more rain.
Although “Arthropod Pests of Equines” notes that some species can develop in well-drained soil, moisture’s important to most.
Let’s begin with the eggs, which a female tabanid prefers to deposit on blade-type vegetation growing in or overhanging quiet water or boggy ground. One by one she cements 200 to 500 (or more) wee, narrow eggs into a blob that’s usually covered by waterproofing goo of her own manufacture.
The blob starts out white but soon turns brown.
According to the UA Extension pamphlet “Horse Flies and Deer Flies on Cattle,” the eggs hatch in four to seven days. Merrily wriggling maggots plop into the water or onto moist soil and quickly nuzzle down into mud. There they munch organic decaying mucky stuff and any soft-bodied grub-like wormy things that can’t wriggle out of their way. (Like earthworms.)
Larvae eat, grow, molt and … well, pretty much that’s it: eat, grow, molt, eat, grow, molt for a few months to more than a year, depending on species and weather. Eventually, when they’re three-quarters of an inch long (or shorter), they scootch upward into drier soil, stop eating and pupate.
Encased in a dark, segmented shell that’s kind of like translucent brown Bakelite, the pupa lies still, looking inert but actually busily rearranging biochemicals into body parts. After three weeks or so - tada! - the adult tabanid emerges.
YUMMY
Males and females first drink nectar from plants. Nectar provides carbohydrates to power flight and mating, says Kelly M. Loftin. Loftin is an Extension Service entomologist and associate professor at the UA at Fayetteville whose specialties include livestock pestsand imported fire ants.
“Mating occurs in flight,” he says. Once mated, the female is fertile for life. All she needs is a dainty sip - of blood - to produce some eggs.
“Males usually die soon after mating,” he says, adding that adult males live two to six days. “The longevity of females is not clearly known, but in the laboratory … females collected after taking a blood meal have lived as long as 42 days after capture if given a sugar water solution.”
Loftin adds that most adult females die of old age before winter or are eaten by predators (including birds and dragonflies).
And what does she do with her one and only life?
MOUTH PARTS
The female tabanid can lay blob after blob full of eggs. Although a few species will produce eggs without it, for most, Loftin says, the fertile tabanid needs a blood meal for each new batch.
She is well equipped to get what she wants. Her large compound eyes appear to distinguish shape, certain colors and movement, and she can sense carbon dioxide (from respiration) and other chemicals associated with large mammals, including, Loftin says, octenol, ammonia and phenols.
She has two kinds of mouth parts. Scissors-like parts cut deeply into the host’s skin and sponge-like parts lap up the blood. To ensure it flows, she produces a salivary anticoagulant, Loftin says. So in addition to the pain of the bite, the host will have an immune reaction to that chemical, creating a welt.
“There is not a tremendous amount of information about where they spend the time between engorgement and egg laying,” Loftin says, but it’s believed the females rest on foliage. They are daytime feeders, and they prefer sunny spaces to shade, and they like temperatures between 72 and 90 degrees. Loftin says they’re attracted to black and shades of blue and red.
Most tabanids are less active on overcast days, and they seldom enter sheds and stables when the lights are off - which horses seem to know. When flies are abundant, horses linger in their stable.
Loftin’s “not aware of anything effective as a camouflage” although wearing light-colored clothing could help. “In some situations, protective mesh outdoor gear can be worn,” he suggests.
EASY TO DISLIKE
Along with pain, they spread diseases among livestock and potentially people. Tabanids are efficient mechanical vectors of disease, as Loftin puts it, “because they are painful and persistent biters. With the pain they inflict during feeding, they are routinely dislodged during feeding and after being dislodged they may resume feeding on another animal.”
Whatever pathogens were in the first animal’s blood are quickly injected into the bloodstream of the next. Even if they aren’t made ill, fly-harassed animals lose weight.
Among livestock in Arkansas, the two most common disease concerns are:
Equine infectious anemia(EIA), which causes high fever, anemia, weakness, swelling of the lower abdomen and legs, weak pulse, irregular heartbeat and sometimes sudden death;
Anaplasmosis (a bacterial disease that causes severe anemia and wasting).
And what about people?
“In the U.S., horseflies are capable of mechanical transmission of tularemia, also called rabbit fever [a disease caused by the bacterium Francisella tularensis],” Loftin says. “However, in the U.S., most cases of tularemia transmission are from the bites of infected ticks or handling infected wild rabbits.
“In Africa, certain deerflies can transmit a disease called loiasis. Loiasis is a disease that is caused by the African eyeworm [Loa loa, a filarial nematode].”
Bottom line: Tabanids are a pain. But they don’t thrive in a dry summer. They will not pester us forever.
Information for this article was contributed by Alyson Hoge of the Democrat-Gazette.
ActiveStyle, Pages 23 on 07/22/2013