The spider fly, forest fly, or New Forest fly, Hippobosca equina, is widely distributed throughout Europe, Asia, and Africa. These winged keds parasitize horses and sometimes cattle (1). The forest fly's bite is characterized as a nuisance and disturbance to large domestic animals. It has a predilection for feeding sites in the perineal region and between the hind legs. (See images of forest flies on the and perineal areas of a and a .)
Hippobosca equina (forest fly) in the forefront on the head of a horse with other flies.
Hippobosca equina (forest fly) in the forefront on the head of a horse with other flies.
Courtesy of Dr. Steffen Rehbein.
Hippobosca equina (forest flies), biting flies in the Hippoboscidae family on the perineal area of a horse.
Hippobosca equina (forest flies), biting flies in the Hippoboscidae family on the perineal area of a horse.
Courtesy of Dr. Steffen Rehbein.
Hippobosca equina (forest flies), biting flies in the Hippoboscidae family, on the perineal area of a cow.
Hippobosca equina (forest flies), biting flies in the Hippoboscidae family, on the perineal area of a cow.
Courtesy of Dr. Steffen Rehbein.
Hippobosca equina (forest fly) in the forefront on the head of a horse with other flies.
Hippobosca equina (forest fly) in the forefront on the head of a horse with other flies.
Courtesy of Dr. Steffen Rehbein.
Hippobosca equina (forest flies), biting flies in the Hippoboscidae family on the perineal area of a horse.
Hippobosca equina (forest flies), biting flies in the Hippoboscidae family on the perineal area of a horse.
Courtesy of Dr. Steffen Rehbein.
Hippobosca equina (forest flies), biting flies in the Hippoboscidae family, on the perineal area of a cow.
Hippobosca equina (forest flies), biting flies in the Hippoboscidae family, on the perineal area of a cow.
Courtesy of Dr. Steffen Rehbein.
The winged adult is approximately 10 mm long with a flattened, shriveled body. The life cycle is similar to that of the sheep ked, Melophagus ovinus, in that the female produces one larva at a time, and at the time of maturity the larva falls away from the female fly and pupates in the soil.
Treatment is rarely indicated; however, many of the repellents used for other blood-feeding periodic parasites may be used.
For More Information
References
Maślanko W, Szwaj E, Gazda M, Bartosik K. Hippobosca equina L. (Hippoboscidae: Hippobosca)—an old enemy as an emerging threat in the Palearctic zone. Int J Environ Res Public Health. 2022;19(24):16978. doi:10.3390/ijerph192416978
