CASE NOTES

Wallaby louse flies (Ortholfersia phaneroneura, Speiser) infesting eastern grey kangaroos on the Central Tablelands of NSW

Bruce Watt, Central Tablelands Local Land Services, David Britton and Narelle Sales, Elizabeth Macarthur Agricultural Institute, Menangle

Posted Flock and Herd November 2023

Introduction

The Hippoboscids are a cosmopolitan family of aberrant flies that are markedly adapted to parasitism. Almost all live on the blood of mammals or birds and have dorso-ventrally flattened bodies and claws enabling them to move in a rapid spider-like fashion through the hair or feathers of their host. Most are capable of flight but tend to fly only short distances. Many have veterinary significance because their bites are irritating, their blood sucking can cause anaemia and because they can transmit blood-borne diseases (Maslanko W, Szwaj E, Gazda M and Bartosik K, 2022).

This paper contains a report of a native Hippoboscid, the wallaby louse fly (Ortholfersia phaneroneura, Speiser), infesting grey kangaroos (Macropus giganteus) in the Palmers Oaky district between Bathurst and Mudgee.

History

In early January 2023 a landholder from northeast of Bathurst noticed 10-15 flies on the body, particularly the inguinal area, of an eastern grey kangaroo that had just been shot. These flies appeared to be blood suckers and flew from the dead kangaroo to his dogs when they were disturbed.

IDENTIFICATION

One fly was killed and collected into an almost-empty coffee cup. In the fullness of time the fly was loosened from the coffee residue in 10% buffered formalin and submitted to the Elizabeth Macarthur Agricultural Institute (EMAI) for identification. The insect was grossly identified as a wallaby louse fly. It was confirmed and keyed to Ortholfersia phaneroneura (Hippoboscidae) by one of the authors (DB).

Image 1. Wallaby fly (Ortholfersia phaneroneura), Field Guide to the Insects of Tasmania

Discussion

An experienced local farmer (from the Palmers Oaky district) commented that he has observed wallaby louse flies on wallaroos (Osphanter robustus), eastern grey kangaroos and wallabies (Wallabia bicolour) for many years. He observed that they infest about half a percent of these animals, usually those in the poorest condition.

Wallaby louse flies feed predominantly on wallaroos, grey kangaroos, wallabies and pademelons (Thylogale spp) but freely transfer to other warm-blooded animals. They are mostly found along the east coast of Australia from Queensland to Tasmania. One of the authors (DB) commented that on his property at Wedderburn, NSW, wallaby louse flies never attempt to feed on non-macropod hosts (himself, family and dogs), even though they commonly end up on them via the dogs. When they land on people, they don't probe the skin, but cause irritation by running through their hair.

These flies are well adapted as ectoparasites with their flattened bodies and feet that can hook and hold onto hairs. The live young, deposited singly, pupate soon afterwards.

Other Hippoboscid flies are either a threat or a problem to both Australian and overseas animals (and people). Best known in Australia is/was the wingless sheep ked or sheep louse fly (Melophagus ovinus), an obligate parasite that completes its life cycle entirely on the sheep. It has been recorded as infesting sheep and goats in the cooler wetter parts of Australia, causing anaemia, weight loss, skin irritation and fleece derangement. In 1964-65, 73 NSW properties were under quarantine for ked, requiring compulsory dipping (Seddon 1967). Sheep ked has not been reported in Australia for many decades now, more due to potent insecticides used to control lice and flies than to regulatory efforts.

Many Hippoboscid flies parasitise birds. The cosmopolitan pigeon fly (Pseudolynchia canariensis) has been recorded in Australia causing painful bites, blood loss and irritation, especially in young birds. They also transmit the pigeon blood protozoan Haemoproteus columbae. Flies from the related genus Ornithomyia parasitise wild birds in Australia.

The cosmopolitan horse louse fly (Hippobosca equina) is a potential pest in Australia. It was first reported on horses and cattle in north-western Western Australia in 1907 and on horses near Buderim, Queensland in 1916. It was then found on horses near Proserpine in Queensland in 1941 and was regarded as a serious pest (Seddon 1967). These infestations were either eradicated or died out and the authors did not find any recent reports of its occurrence in Australia.

In Eurasia and Tropical Africa however, horse louse flies are an increasing animal and human health and welfare threat. They usually parasitise horses but can attack cattle, dogs, pigs and people. They are known to harbour Corynebacterium pseudotuberculosis equi, Bartonella spp. and Anaplasma spp. Horse louse flies attack people working outdoors and both their bites and habit of scurrying rapidly on the skin and through the hair is described as remarkably irritating. Horse louse flies are also potential vectors of zoonoses (Maslanko et al. 2022).

References

Speiser PGE (1902) Studien Uber Diptera Pupipara Z. Syst. Hym. Dipt. 2:145-180
Field guide to the Insects of Tasmania, accessed 4 April, 2023 tasmanianinsectfieldguide.com
Maslanko W, Szwaj E, Gadza M and Bartosik K (2022) Hippobosca equina L. (Hippoboscidae: Hippobosca) - An Old Enemy Emerging as a Threat in the Palearctic Zone International Journal of Environmental Research and Public Health 19(24)
Seddon HR (1967) Diseases of Domestic Animals in Australia Part 2. Arthropod Infestations (Flies, Lice and Fleas), pp 90-98