AMHERST, Mass. (WWLP) – New UMass Amherst research suggests that we need to pay more attention to flies landing on our food.

“Synanthropic” flies, or non-biting flies that live with us, need their attention turned to them being disease carriers. Epidemiologists have focused on the biting flies that can spread disease by transferring injected blood from host to host, however the non-biting flies regurgitate is a greater risk to human health.

Nicknamed the “Lord of the Flies,” John Stoffolano has been studying the common insects for decades as a professor of Entomology at UMass Amherst. He said these flies don’t usually get the attention mosquitos do, but their impact on the spread of disease is important.

“I’ve been working on synanthropic flies since I was a graduate student in the 1960s,” says Stoffolano. “And synanthropic flies have largely been ignored. Blood-feeding flies have taken the limelight, but we should pay attention to the ones that live among us because they get their nutrients from people and animals that shed pathogens in their tears, feces and wounds.”

As the common housefly buzzes in and out of your house, it can feast on a variety of foods such as roadkill, animal dung, rotting garbage, and more. Each time it eats, it fills it crop. “The crop is like a gas tank,” says Stoffolano, “a place to store food before it makes its way into the digestive tract where it will get turned into energy for the fly.”

The crop is a place for storage, not digestion, and there are very few digestive enzymes or antimicrobial peptides, both of which neutralize most pathogens at work. In short, the crop becomes a place to store disease-producing pathogens.

When the fly takes off, crop filled with fresh dog feces or roadkill, it gets rid of excess water in its crop by “bubbling” or regurgitating the water out and mists everything it contacts. Then the fly comes into your home and lands on the sandwich you are making. When it lands, it regurgitates some of what’s left in its crop right onto your bread, along with whatever illness-causing pathogens that the fly happened to ingest.

A fly’s crop is just one of the cauldrons where microbes develop antibacterial resistance, what gets sprayed on your food might not respond well to conventional treatments.

“It’s the little things that cause the problems,” Stoffolano says. “Our health depends on paying closer attention to these flies that live with us.” 

What researchers don’t know is how much common house flies really regurgitate and if that would cause an infection. He said some important steps in the meantime are making sure we keep areas like bathrooms clean.

If your home is close to a dump and you see flies, you should use fly tapes. However, this doesn’t mean you need to panic.

“I would think that if a fly landed on your fried dough at the Big E that probably is not a problem but these are things that we’re looking into,” Stoffolano said.

Professor Stoffolano hopes this will inspire more research into how diseases spread amongst animals.