As well as the horn fly, the Family Muscidae includes the house fly (Musca domestica), the face fly (M. autumnalis) and the stable fly (Stomoxys calcitrans). Male and female horn flies and stable flies blood feed on their hosts.
Host range and geographic distribution
Life cycle - direct
Adult male and female H. irritans are almost obligate parasites of cattle and spend most of their time on the hosts. They tend to congregate along the back and withers and around the head. The adult females mate only once, in the hair coat, and then leave the host for short periods to lay eggs in freshly passed cattle feces on the ground. Under ideal conditions the eggs hatch in a day. There are three larval stages lasting approximately a week and the larva then produces a cocoon and pupates. After approximately one further week, the adult fly emerges from the pupa and quickly finds a new host. Thus there can be several generations of horn flies in a summer.
Pathology and clinical signs
Treatment and control
A large number of topical products, including ear tags, as well as the topical (pour-on) preparations of the endectocides, are approved in Canada for treatment and control of horn flies on cattle. Some cannot be used in lactating dairy cattle. These products, properly applied, can be quite effective because the flies spend almost all their lives on the hosts. A major problem in Canada, however, is the widespread resistance of the flies to the synthetic pyrethroids used for control. In Canada, the use of the non-endectocide products is controlled by the Pest Control Products (PCP) Act.
Several avermectin products (most applied topically - pour-ons) are approved for horn fly control in Canada.
|Carbaryl||SEVIN, DUSTING POWDER|
|Cyfluthrin||CYLENCE POUR ON INSECTICIDE|
|Cypermethrin and Diazinon||ELIMINATOR EAR TAGS|
|Diazinon||PROTECTOR AND Y-TEX EAR TAGS|
|Dichlorvos with Pyrethrins||DISVAP III|
|Ivermectin||IVOMEC POUR-ON AND OTHERS|
|Lambda-cyhalothrin||SABER EAR TAGS AND POUR-ON|
|Pyrethrins in combination||DISVAP IV|
|Rotenone and Sulphur||DRI_KIL LOUSE POWDER|
|Tetrachloviphos||ENGAGE AND ECTOGARD CATTLE INSECTICIDE EAR TAGS|
Additional information on the product mentioned is available from the Compendium of Veterinary Products (Twelfth Edition, 2011), or from the manufacturers.
Public health significance
Although horn flies will sometimes cause annoyance to people, especially those working with affected cattle, other than horses they feed on other hosts only very rarely.