Horn Flies on Livestock

hornflies

Ag Biz News Column
Chad Gulley
County Extension Agent –Ag/NR
Smith County

 Protecting Cattle from Horn Flies

In Texas, one of the most damaging insect pests to cattle is the horn fly.  Horn flies are typically found on the animal’s back, shoulders, and sides.  Horn flies can be a problem for cattle from spring to early fall, with peak fly populations in early summer.

Research has shown that a calf infested with more than 200 horn flies will gain 15 to 50 pounds less than normal from birth to weaning and sale.  Horn flies can also reduce milk production in dairy cows by up to 20 percent.

Horn fly eggs are laid in cow manure where the eggs hatch into maggots.  The horn flies develop from the egg to the adult stage within 10 to 20 days.  The adult horn fly lives about 3 weeks feeding 20-30 times a day.  Horn flies have piercing mouth parts.

To control horn flies effectively and economically it is important to first identify the fly species on your livestock.  It is also important to know what control methods to use for the different stages of the fly’s life cycle.  Managers also need to know when to take action and how to reduce the pest’s resistance to various controls.

Three types of control methods are used to suppress horn flies.  These methods include biological, cultural and chemical controls.  Producers who use all three methods employing integrated pest management (IPM) will reduce horn fly populations the most while incurring the least expense.

Biological controls include some insects that naturally prey on the horn fly or horn fly larvae.  These insect species may suppress horn fly populations naturally.  Cultural controls include removing or disposing of fresh manure around barns and stalls.  This helps to interrupt the horn fly’s life cycle preventing new populations from developing.

Chemical control methods include sprays, dusts, and ear tags to name a few.  Be sure to read and follow all label directions when choosing to incorporate chemical control in the  management plan.  It is also important to rotate classes of insecticides every year to prevent the horn flies from building up a resistance to the product used.

Regardless of the method chosen, do not treat infestations of less than 200 flies per animal.   Treating too early or with few flies on the livestock can lead to resistance by the flies as well as not be economical.

There are other fly species that can be a problem for livestock.  The stable fly, face fly, and the house fly are other species that may be a problem around our livestock species.  Proper identification is important to insure the best plan of action in the control of these insect species.  Feeding habits and size of the fly are some distinguishing factors that may help decide which species we are dealing with.  Horn flies are much smaller than the other mentioned fly species.

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