Do they really bite? Do they suck a small amount of the blood while on their host – or are they simply living off dry skin - as previously believed ?
The louse fly of cheetahs belongs to the genus Hippobosca within the family Hippoboscidae, but is commonly known just as the ‘louse fly’. Even though these flies have a pair of large wings and are strong fliers, they seldom leave their hosts to which they cling by means of two strong claws at the tip of each of their six legs. The high rainfall over the past few years has perhaps become one of the reasons, that we have noticed an increase in the number of the hardy ‘cheetah flies’ on the cats that are part of our Care Centre. After discussions with the vets who assist AfriCat and a noted concern from Team AfriCat, that their numbers seem to be increasing – we can now confidently support an article from Iowa State University and an article written by Professor Ivan Horak, which fully supports AfriCat’s theory that the Hippobosca longipennis or otherwise commonly known as ‘the cheetah fly’, are blood sucking and not detritus feeding. They scuttle between the fur, hair or feathers of their hosts and only fly off if they are in immediate danger of injury or capture. They have piercing mouthparts and their bites are irritating and painful and they live off the blood of their hosts.
What this means is that we have to start looking at a much more intensive control programme otherwise, with the numbers we have noticed over the last month, there is a good chance that some cheetah may become anaemic before long. Additionally, they are not obligate cheetah flies, but have also been found on a number of other carnivores.
So, to recap for all out there that have been introduced to this fly on a game drive or while tracking cheetah…
Hippobosca longipennis, is a blood-sucking parasite found mainly on carnivores. Its bites can be painful and irritating, although not all animals appear to be bothered. Heavy parasite burdens can occur on some animals: in one case, 180 specimens were found on a single captive cheetah. Extensive blood loss might be possible. H. longipennis is an intermediate host for Dipetalonema dracunculoides, a filarial parasite (thread-like, parasitic nematode worm) of dogs and hyenas. It may also be a vector or transport host for other pathogens.
Carnivores are the preferred hosts, as well as the only effective breeding hosts. H. longipennis has been found on a wide variety of carnivores including cheetahs, lions, leopards, lynx, servals, African wild cats (Felis silvestris libyca), African civets (Civettictis civetta), hyenas, jackals, African wild dogs (Lycaeon pictus), foxes, badgers, mongooses and domesticated dogs and cats. There have been occasional reports of infestations on other species including roe deer (Capreolus capreolus), antelopes, livestock, humans and a bird; it is uncertain whether all of these parasites were correctly identified.
- longipennis seems to be adapted best to warmer areas and its distribution seems to be limited by low temperatures and high humidity. This fly appears to have originated in Africa, where it is widespread in all but the more humid western and central regions. It can also be found in suitable habitats in much of the European and Asian Palearctic Region south of about 45º north latitude. H. longipennis is occasionally reported from countries on the fringes of this range (e.g., Ireland, Germany, Poland, Taiwan and Japan).
- longipennis has probably entered the Americas many times without becoming established. The most serious incursion was in 1970, when infested cheetahs were imported from East Africa to the San Diego Zoo in California. The fly was not identified until 1972 and not fully eradicated until 1975. In the interim, other infested cheetahs were discovered in zoos in Georgia, Oregon and Texas. They were also treated successfully. In 1983, H. longipennis flies were found in North Carolina on a shipment of bat–eared foxes from Africa. Outbreaks also occurred in Ireland in 1982 and Japan around 1990, both times on cheetahs imported from Namibia.
In contrast to most other fly species, louse flies do not lay eggs, but a single egg develops to a pupa within the uterus of the female fly. The pupa is large and gravid female flies can easily be distinguished from males by the size of their abdomens. The female fly leaves the host to deposit the pupa in a sheltered spot, where the pupa casing hardens and from which an adult fly emerges within a few weeks. The newly emerged fly then flies to a host animal and the life cycle commences all over again. The female fly can deposit a single pupa every seven to ten days and she can live for several months.
The winged adults seek out suitable hosts and feed several times a day. On dogs, they prefer the ventral neck and front axilliary regions. After approximately seven days, the flies mate on the host. The larvae develop internally for three to eight days, the female then deposits the larva on the soil, in cracks or crevices, under plants or on debris. After larviposition, she returns to the host to feed and begin another larval maturation cycle. Individual females may live for four or five months, but about half that is more typical. Each female usually bears 10 to 15 offspring over a lifetime.
- longipennis is a member of the family Hippoboscidae and order Diptera (suborder Cyclorrhapha). This fly is related to sheep keds. Hippoboscid flies have a sleek, dorsoventrally flattened head and body, powerful.
Wild louse flies, although irritating, never reach numbers at which they pose a threat to the health of their hosts. However, when hosts are kept in captivity, the numbers of flies increase considerably because of the ready availability of hosts and hence blood-meals. Consequently, cheetahs in breeding programmes and cattle in feedlots can become heavily infested with flies and the constant irritation of their bites can lead to extreme discomfort.
Because it is impractical to track down and destroy the pupae, one has to resort to treatment of the host animals to control the number of adult flies. This can be done by means of insecticides administered as powders, or as dips, or in topically applied formulations.