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Love the Summer but Hate the Flies? This Weaponised Wasp could Help Win the War
Could a tiny black wasp defeat that irritating invasion of flies that mars the splendour of summer holidays in the French countryside (and elsewhere)?
The common house fly — Musca domestica — is one of the most widely distributed (and detested) insects on earth, living in every corner of the planet where man is also found. If you are within fly commuting distance of a local farmer and his animals, the chances are more than certain that come this summer you will be sharing your home, your garden, your barbecue, yourrandonée, your sun lounger and your annual holiday with bothersome, buzzing, biting, pesky, persistent flies.
In France the people most at odds with the fly are the country’s thousands of livestock breeders many of whom produce award-winning and highly prized meat and poultry for France’s renowned cuisine de terroir.
Flies thrive wherever there is livestock in any shape or form forcing farmers to spend large amounts of money on chemical and physical control systems to contain the problem not to mention the discomfort they endure while working surrounded by these annoying insects.
The writer recently interviewed some goat farming neighbours in the south western département of the Lot who are trialing a new biological product they hope will change the landscape in terms of the War on the Fly. Supplied by Koppert, a Dutch firm making a wide range of biological agricultural products since 1967, the goat breeders are now experimenting with this biologically engineered product. During a visit they described what was involved: first they sprinkle specially supplied mini wasp larvae in various strategic locations around the barns and the farmyard. These larvae contain a small parasitic wasp known as Muscidifurax raptorellus. These tiny black wasps hatch from their pupal shell in two and a half days and the female then beings an immediate search for fresh fly pupae in which she lays her next generation of wasps. The wasps eat the fly larvae thus reducing the problem at source as it were. The wasps go on to repeat the cycle after two to three weeks. It is early days yet , the neighbours say, but the goat farmers are optimistic as first results seem promising, something not only the farmer but also us fly-victimized neighbours look forward to enormously.
Slightly further afield in the adjoining département of Corrèze (coincidentally home to one former and one current French head of state), livestock farmer Ubald Cheno began using the mini wasps five years ago after his fly problem became so bad he was forced to call in a livestock technical advisor. M. Cheno reports that from the second year of use he saw fly numbers decrease dramatically. He no longer introduces a new batch of wasp larvae each year as they appear to have established themselves in sufficient numbers to deal with the ongoing fly breeding cycle.
The house fly can complete its early life cycle from egg to adult in seven to 10 days and then continue to live as an adult for a further infuriating 15 to 30 days. In that time the female will lay an average of 500-600 eggs which take just 24 hours to hatch in warmer weather offering a multiplication potential that is staggering. In the United States the University of Nebraska released an scientific estimate showing that between April and August and providing the offspring of a single pair of flies all survived, the grand total of misery added by this pesky species would be 191 010 000 000 000 000 000 flies!
Man’s animosity toward the lowly fly seems to go back deep in time. Ancient Egyptian hieroglyphics depict flies even before their famous biblical appearance in the show down between Moses and Pharaoh. The animosity between them and us is not surprising when you consider that each fly is capable of carrying over one hundred different pathogens including typhoid, salmonellosis and anthrax. The amount of human disease and death they can provoke is inestimable.
Despite our disdain and loathing for an unhygienic, disease-carrying nuisance, one has to admire the fly for its ability to …well… fly. The puniest house fly is able to perform manoeuvres that are far beyond the reach of even our most sophisticated fighter aircraft. They can accelerate at twice the speed of gravity, make six turns per second and fly straight up down or backward. They beat their wings at an amazing two hundred beats per second and can reach top angular speed in two one hundredths of a second.
As Koppert the makers of the eco-friendly weaponised wasp note: “Stable flies can cause huge problems on poultry and pig farms. Large numbers of flies irritate the animals resulting in decreased production of eggs, meat and milk. The common housefly (Musca domestica) and stable fly (Stomoxys calcitrans) are the most commonly found species in the stalls. The housefly can produce 15 generations in one year. The white larvae, in the form of legless maggots, develop in stable manure and other substances. In favourable conditions they pupate after one week. The stable fly is often found sunning itself on walls, trees, and fences. It resembles a housefly, but has a stiletto-like mouthpart extending straight outwards, which it uses for sucking blood. The life cycle of this species is the same as that of the housefly. The stable fly bites animals and sometimes humans, particularly on the legs. The bite is quite painful”.
Writer: Mike Alexander
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