Parasitic Insects, Mites and Ticks: Genera of Medical and Veterinary Importance/Louseflies

Louse-flies and Keds (Diptera, Hippoboscidae)
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Characters of hippoboscid flies
These flies can be mistaken for large lice or ticks because of their sedentary feeding habits on their hosts. This is particularly the case for the Sheep-ked (Melophagus ovinus) which never develops wings, and Lipoptena species (Deer-keds) which shed their wings as soon as they have found a host after emergence from the puparium. Reproduction by hippoboscids is by larvipary. One egg at time develops into a larva within the female's oviduct. It develops fully and pupates as soon as it emerges from the female.
 * Photograph shows Melophagus ovinus adult Sheep-keds (male left, female center, and a puparium at right). These wingless flies remain permanently ectoparasitic on their hosts and the female glues each puparium she lays onto the hair of the sheep.

These flies have piercing mouthparts to feed on blood; the long thin mouthparts are retracted into head when not in use. Hippobosca species fly actively from host to host. Melophagus ovinus is resident on its sheep host for its complete life-cycle. Despite the active feeding by both sexes these flies are mostly important for biting-stress, not transmission of other pathogenic parasites.

Glossary

 * Ked = Vernacular term for Melophagus ovinus, the hippoboscid fly that infests sheep.
 * Larvipary = Reproduction in which an egg develops in the female to form a single larva which then develops fully within the female, the mature larva is then laid and rapidly forms a puparium inside which it develops into a pupa. Compare with larvipary by Tsetse-flies (see Houseflies and similar).
 * Palp = A pair of sensory organs associated with the mouthparts. On hippoboscid flies the piercing mouthparts are retracted within the head when not in use.
 * Puparium = A case that is formed from the body wall of mature larvae of some dipteran flies; inside this case the larva changes into the pupal stage of complete metamorphosis.

Melophagus (Hippoboscidae)
Characters: adult, dorsal. 1- Palps are prominent below the head. 2- Antennae are compacted into pockets in the head, and a few long setae protrude from them. 3- Eyes are relatively small, and brown. 4- Legs are long and stout and equipped with a pair of large claws. 5- Wings never develop. 6- Segmentation is not evident on thorax and abdomen; body is grey and brown and bears many setae.

Hosts: Melophagus ovinus infests sheep.

Signs and disease: Sheep-keds cause irritation, pruritus, biting-stress, soiling of wool with ked feces and depilation. Allergic dermatitis develops at the feeding sites causing to prepared hides the damage known as cockle.

Hippobosca (Hippoboscidae)
Characters: adult, lateral and dorsal. 1- Palps protrude prominently below head. 2- Antennae are compacted into pockets in the head and have a few long setae protruding. 3- Abdomen is either flattened dorso-ventrally or is stout (as shown) because it contains a developing larva; segmentation of the abdomen is not clear. 4- Legs are long and stout; they end in a pair of large claws. 5- Wings are well developed with thick veins toward the leading edge and no veins toward the trailing edge. 6- These are large, robust, shiny brown flies. 7- Eyes are large, widely separated, and brown.

Hosts: Hippobosca rufipes and H. variegata (Cattle louse-fly) feed on cattle and horses. Similarly: H. camelina (Camel louse-fly) on camels; H. equina (Horse louse-fly) on horses; H. longipennis on dogs.

Signs: Hippobosca species of Louse-flies move rapidly from one animal to another within a herd of livestock by flying. These flies take repeated small meals of blood. Also they will spend much time clinging to hair coat of their host.

Disease: Irritation and biting-stress are caused.

Distribution: Hippobosca flies inhabit Europe, Africa, Middle East, Central and South East Asia.

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