Page 30 - April 2022 Parker County 4-H Connection

Face flies

Face flies mainly affect cattle and horses. As the name implies, these insects feed on the secretions around the eyes and nose, and they are a
major vector of pinkeye infection in cattle. Like the horn fly, face flies usually lay eggs in fresh manure, but this pest will fly long distances
between feedings. Unlike horn and stable flies, face flies are not blood feeding insects, but the spongy mouth parts are highly abrasive.
“It can mechanically transmit a little bit of bacteria in some of these tissues, but they’re not a blood feeder,” Tarpoff said. “They’re difficult to
control, because they don’t spend much time on our animals.” Face flies have also been implicated in the transmission of eyeworm in cattle.

House flies

House flies are one of the most common pests. While annoying, they are not a major factor in disease spread in livestock populations.
“We’ve documented that they can transmit different bacteria from one animal to another, but really, this is a nuisance pest,” Tarpoff said.
House flies swarm in large numbers during different periods of the day. Adults feed on available blood, sweat, tears, saliva and other bodily fluids.
Instances of secondary wound myiasis have been recorded in which house flies lay eggs in open wounds.mm“They will lay their eggs and open
kind of perineal wounds,” Tarpoff said. “So even if we do have an infected—particularly vesicular stomatitis premise—some of those lesions may
secondarily get a little bit of fly strike, because these house flies will congregate to some of those lesions on the outside.”
House flies tend to rest in sunny areas, whereas stable flies prefer shade. “If you look on the side of your barn or the side of your house during the
heat of the day, and you see massive numbers of flies, believe it or not, those are house flies,” Tarpoff said.

Control and treatment of external parasites

Tarpoff noted there are many product and treatment options available to ranchers and livestock owners to help control external parasites.
Feed-throughs, ear tags, pour-ons, sprays, dusters or oilers, premise treatments and other options may be useful in controlling pests. “If I had a
list, it would be about a mile long and wide about how much we actually have,” Tarpoff said. Feed-through products are available for a variety of
livestock species. “These are products that are fed to the animal,” he said. “They do not affect the animal. It gets passed into the manure and into
the environment where some external parasites will lay their eggs, and that’s how they actually interfere with the general population in an area.”
Feed-throughs are most effective before the vector season begins, Tarpoff added. Ear tags impregnated with insecticide are another popular
control method used effectively in cattle. But producers must remove them at the end of the season to help with resistance, which Tarpoff warned
is a pressing issue. “If we don’t remove them at the end of the season, we can actually incur more resistance issues in the next few years,” Tarpoff
said. “We can have season-long duration with these as we have constant exposure, since they’re constantly on the animals.” Resistance generally
occurs because there’s either too low of a dose of product for a long period of time, or the insect has been exposed to the same insecticide classes
for multiple years in a row and has evolved some natural defenses against the product. Tarpoff said rotating insecticides is the best way to
prevent resistance as flies become resistant to pyrethrins more quickly than some other chemicals. “We can do a pyrethrin no more than one set
of every three years followed with an organophosphate for two years,” he said. “If you have questions about this, please visit with your local
veterinarian.”

Pour-ons and sprays are usually not as susceptible to creating resistance, because they don’t have much residual activity, he noted.
“The residual activity with ear tags is because we have constant exposure for up to five months,” Tarpoff said. “With pour-ons and sprays, they get
into the environment, they work, and they go away.” A variety of self-treatment applicators are available. These require animals to rub against or
walk under the applicator, which then dispenses product, but Tarpoff said not all animals will use them when in a group. “If you do have a group
of animals and you’re using some of the self-treatment dusters, oilers or rubs, make sure that there is a little bit of unique fencing around strategic
areas and force them to use them on a daily basis,” he said. “We’ll get maximum effectiveness.”
Tarpoff concluded one of the best methods of controlling parasites is environmental management. “Cleanliness is the key to external parasites,”
he said. “Managing manure, making sure we’re disrupting, and we’re not leaving piles of older manure areas that are heavy traveled.”
Undisturbed piles of manure, decaying hay and bedding and improper waste disposal all increase the availability of desirable habitat for flies and
other pests. “Making sure that if we can knock down vegetation on our fence lines and around our perimeter, that’s a pretty good step to take and
controlling external parasites,” Tarpoff said. “Any area that we have water holes and things like that. If it looks like it’s going to harbor mosquitoes,
it can probably harbor some of these other parasites, as well.”

For more information on the different insects and pests and a library of pesticides available for use in Texas, visit the Texas A&M AgriLife
Extension Service’s Livestock Veterinary Entomology division.
July 31st, 2020|0 Comments

29 PARKER COUNTY 4-H CONNECTION / APRIL