Tumblebugs and horn fly control

0
972

A few weeks ago, my friend Dr. Ralph Mirarchi, a wildlife biologist, told me about seeing green tumblebugs rolling balls of dung along the gravel road leading to his house. He lives in a secluded area north of Loachapoka. He concluded that the rolling balls were coyote poop. He said deer don’t have a habit of defecating on his road, but that coyotes regularly do. There are no livestock of any kind being farmed anywhere in the vicinity of his property.
I’ve seen a few of the green tumblebugs he described, but that was prior to to the disappearance of the common black tumblebugs that once were common in grassy pastures where cattle grazed. Back then, the tumblebugs would alight next to a pile of fresh cow manure , carve off a piece, form it into a ball, roll it some distance away, and bury it. Before covering the ball, the female would deposit eggs on it. Upon hatching, the larvae would feed on the manure ball until they pupated.
Prior to the precipitous decline in much of this dung beetle’s range, the American Institute of Biological Sciences estimated that tumblebugs saved the U. S. cattle industry $360 million annually by spreading the manure and improving the fertility and quality of the pastures they inhabited.
In addition to the tumblebugs’ obvious benefit in improving pastures, they and some other dung beetles are important in another respect. They reduce horn fly populations. Horn flies are blood-suckers, they annoy the cows, and are capable of spreading mastitis and possibly anaplasmosis. Their ability to rapidly develop resistance to insecticides makes them difficult to control. Horn flies breed in cow manure. Dung beetles, including tumblebugs, reduce the flies’ breeding places, and some dung beetles prey on the flies’ eggs and larvae.
As I recall, common tumblebugs disappeared from these parts about the same time imported fire ants became abundant. That coincidence led me to believe that fire ants, in some way or another, had caused the tumblebugs’ demise. I’ve since changed my mind. I now believe that the chemical, ivermectin, or a related chemical, was the causative agent. Ivermectin is injected into farm animals to kill worms and possibly some other internal parasites. Several reports I have read are in agreement, although some others disagree.
In “Feed Lot,” an article on “Alternative Methods of Horn Fly Control,” written by Heather Thomas, stated, “There are 90 species of dung beetles in North America, including some imported from Africa. The beetles bury 95 percent of horn fly eggs and larvae and 90 percent of internal parasites passes in manure.
“Some types of dewormers and pesticides destroy dung beetles, however, killing at their larval stage. Use of ivermectin products can decimate beetle populations because fresh manure of treated cattle is toxic to beetle larvae.”
Thomas also says Muscovy ducks can help stockmen with small herds to control horn flies. “This breed is not a water duck, it eats insects. They can range freely in pens and pastures, and are prolific breeders. They follow cattle around, searching through manure for fly larvae and scattering the piles. It takes about four ducks per cow to adequately control the fly population. The duck also eat adult flies and will pick the flies off the cattle when they are lying down.”
If you didn’t already know all this, you do now!
Bob Mount is a Professor Emeritus with the Department of Zoology and Entomology at Auburn University. He is also chairman of the Opelika Order of Geezers, well-known local think tank and political clearing house. He writes about birds, snakes, turtles, bugs and assorted conservation topics.

LEAVE A REPLY

Please enter your comment!
Please enter your name here