A recent study showed that cows painted to look like zebras attracted less biting flies.
Researchers from the Department of Biological Production of the Tokyo University of Agriculture and Technology released the study which claims that biting flies are “confused” by the stripes and therefore seek other animals on which to prey.
“The Japanese study was small but showed reductions in numbers of biting flies on animals and in defensive behaviors,” said Dr. Gary Brewer, Professor of Insect Pest Management for the UNL Department of Entomology. “The study involved painting white stripes on black cattle to mimic the appearance of zebras which have a degree of immunity to biting flies in Africa.”
The study, published in the journal Plos One, showed that painting zebra stripes on cows reduced fly bites by about 50% compared to unpainted cows. They believe this could be an environmentally-friendly alternative to pesticides.
“It appears there has been previous research with biting flies avoiding black/white contrast,” said Dr. Grant Dewell, a Beef Extension veterinarian for Iowa State University. “Potentially, either the vertical stripes confuse the fly or it could be the narrowness of stripes, in that polka dots seem to do the same thing.”
In Africa, where zebras are native, tsetse flies are important disease vectors of cattle and other livestock and humans, Brewer said. However, zebra and other African ungulates [hoofed mammals] are relatively free of bites from tsetse flies and of course are iconic for their black and white striping, he said.
“Tsetse fly traps using striped, contrasting black and blue colors are effective and captured stable flies in U.S. trials,” Brewer said. “However, other trials have shown that plain white traps are equally or more effective than the tsetse fly trap design in attracting stable flies.”
Dewell said he found it strange, since black contrast is used in most stable fly traps; but those are almost always horizontal. He said his understanding of stable fly traps is that the fly identifies horizontal contrast as potential prey.
“Probably very similar to how a newborn calf will seek a horizontal contrast when seeking the udder,” Dewell said. “A calf will try to nurse off of a saw horse, fence or cow.”
Nebraska cattle producers struggle with the same species reported on in the zebra-stripe trial done in Japan, Brewer said. In the U.S., stable flies and horn flies are wide-spread perennial problems and horse flies can be an intense problem in limited areas, he said.
“As far as I know it would only work against biting flies that move from host to host,” Dewell said. “It looks like stable flies are the main focus; but I assume horse flies are similar. Horn flies stay on the same host, and I don’t think sight is an issue.”
Brewer said it is important to keep in mind that biting flies, as reported in the study, use both vision and their sense of smell to locate hosts. They use chemical cues, odors, to locate their hosts, he said. As do mosquitoes.
“In Nebraska, we are testing simple white traps to capture stable flies,” Brewer said. “When we add a chemical lure to the trap, the capture rates increase.”
Dewell said he thought if the zebra ploy works on cows it would probably work on any animal you could paint. But, Brewer said, therein lies a practical question: How do you paint cattle in summer pastures that are shy of human contact?
“Painting stripes on cattle may help,” Brewer said. “However, not too many Nebraska cattle will be willing participants in the painting.”
Jon Burleson can be reached at firstname.lastname@example.org.