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Friday, April 15, 2016

SCIENCE: A salute - and solution - to the Australian bush fly

(Reposted from The Polynesian Times)

Demonstrating the Aussie wave, aka Australian salute:

Reporting on the experimental use of a virus to control burgeoning numbers of European carp Down Under, the Wall Street Journal lists "five animals that have gone wild in Australia". Four species are also European imports, but the fifth - flies, of the "bush" type that pesters everyone outdoors  - certainly isn't:

"... it's likely the fly got to Australia in an Aboriginal boat, the same way the dingo got here. In that case, the bush fly might have arrived in Australia as long as 45,000 years ago," says Jim Heath in his Seuss-like-titled 1989 book "The Fly In Your Eye"*

Heath explains that the bush fly needs protein to develop its eggs and is quite happy to find it in human tear ducts, noses, saliva and sweat, not to mention blood and raw meat; hence the plague of them at barbecues. As beef farming grew so did the fly population, feeding and breeding on the droppings of Australia's 28 million cattle. At up to 12 cowpats daily per animal, times up to 2,000 larvae per pat, the herds are potentially fostering quadrillions of flies.

Not just bush flies. Initial efforts to control flies focused on agricultural pests such as the blood-sucking buffalo fly and involved chemicals, to which the insects are increasingly becoming immune

So attention turned to biological controls, and this is where the dung-beetle comes in. Dr. George Bornemissza of the Australian CSIRO looked at native beetles and determined that they couldn't cope, so in April 1967 he began a project to import other species:

The first foreign beetles were from Hawaii, released in Queensland on 30 January 1968The dung-beetles disrupt fly-larval development by shredding and burying manure - which also improves soil quality and helps reduce contamination of run-off water, say the Kiwis, who are using the same strategy.

Because of Australia's diverse climate it was originally estimated that 160 different species would be required; in practice, "a total of 53 species were introduced and of these 23 have established," says CSIRO.

Unfortunately these species tend to cease their activity in early spring before the new season's flies begin to arrive, so two more kinds that are active at that time were introduced in 2012 from France and Spain to southern Australia by Dr Bernard Doube. The entomologist has been calling for a $50 million program to introduce 25 additional species, money which he says will multiply into several billions-worth of extra pastural productivity.

The real salute, then is reserved for the dung-beetle:

* Full text and illustrations on-line at:


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1 comment:

A K Haart said...

Useful little critters, dung beetles.