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Control Fly Takes On A Common Foe To Help Poultry Producers

GAINESVILLE—A small, shiny fly that feeds on pesky house flies may help Florida’s poultry producers save thousands of dollars and squash complaints from their neighbors.

By using the black garbage fly to rid poultry houses of the common house fly, Florida’s poultry industry could reduce the use of pesticides and help the environment, said Hillsborough County Cooperative Extension Agent Roger Jacobs, a poultry specialist with the University of Florida’s Institute of Food and Agricultural Sciences.

“We’ve seen this predator fly work well in controlling the house fly, and Florida’s poultry producers should be able to use this tool to take care of the problem themselves,” Jacobs said. “Not only will producers profit and the environment benefit from decreased pesticide use, but of course the people living around these poultry farms will find less problems with house flies as well.”

Commonly called the black garbage fly or dump fly, this shiny black fly is slightly smaller than the house fly. It can be found in garbage dumps and poultry manure like the house fly, but it prefers darker areas like the bottom floors and manure pits of deep-stack poultry houses and does not typically enter the upper floors or neighboring homes. Dump fly larvae live and feed similarly to the house fly, but they are also voracious predators of house fly maggots, making them important biological control agents, said Jerry Hogsette, a USDA research entomologist and UF/IFAS courtesy assistant professor.

Ranked ninth in the nation, Florida’s commercial egg production industry provides $100 million in farm value annually to the state. With most of Florida’s 10.5 million laying hens located in Central Florida, the state’s deep-stack chicken houses become prime breeding sites for the common house fly, creating a nuisance for both producers and their neighbors who spend hundreds of thousands of dollars a year on fly-killing chemicals, Jacobs said.

This is the first time the predator fly has been available to the state’s poultry producers. Originally trapped on a poultry farm in Hillsborough County, Hogsette established a colony of the dump flies several years ago at the USDA Medical and Veterinary Entomology Research Laboratory in Gainesville. It is the only research colony in the United States.

Unlike the house fly, the dump fly larvae have the ability to paralyze their prey. And unlike most animals in nature, Hogsette notes, the dump fly larvae will kill even more house fly larvae than they will eat.

Hogsette said residents living near Florida’s poultry farms seem to be increasingly concerned with the presence of house flies, and poultry producers want to prevent any possible adverse relationships with their neighbors. In addition, the house fly problem could become a health issue, as some current evidence suggests that house flies may transmit the salmonella bacteria from manure to chickens and potentially to humans, he said.

“What’s so great is that the chances of such problems developing are greatly reduced with the dump fly because it stays in the dark places of the chicken house and not on the upper floors where the hens are,” Hogsette said. “House fly control is super critical, but the emphasis should be on controlling its larval stage and not reliance on tons of pesticides as a remedy.”

Many producers now use insecticide sprays in poultry houses or as a larvicide mixed in the feed for house fly control. Not only are these methods expensive, but the prolonged use of pesticides can eventually result in the development of insecticide resistance by house flies. While poultry manure as a waste product costs producers an average of more than $3 million per year, this expense could be converted into revenue for the producers by having a pesticide-free manure to market to the organic gardening industry, Jacobs said.

Zephyr Egg Co. in Pasco County has more than 2 million laying hens on five farm complexes. To control house flies, Production Manager Frank Bennett has worked with Jacobs in maintaining colonies of the dump fly in five of six houses on one farm site. Bennett said using the dump fly has worked extremely well in controlling house flies, and that the chicken house without the benefit of the dump fly has continued to have house fly problems.

“Not only are we seeing a decrease in the number of house flies, but the value of the manure has increased because it’s purely organic now,” Bennett said. “Any type of natural predator is going to benefit poultry producers by lowering their pesticide costs and providing them with manure that no longer contains poisons and can be marketed for organic gardening. ”