The grim trail of bacteria left by flies in hot weather is revealed

Aug 07, 2013

(Phys.org) —The current hot spell of weather has seen increased activities by flies whether in the kitchen or across picnic food and barbecues.

It may make grim reading but every fly leaves a calling card in the form of bacterial deposits.

These deposits come not only from their legs, but also from the way that they eat - that is vomiting and then sucking up the resulting mixture.

Now scientists at the University of Surrey have mapped out just how much the pesky insects leave behind.

The research involved trapping blue bottle flies in a Petrie dish and then "growing" the resulting .

The results are a bit startling, for example, if a blue bottle has recently fed on faeces it may carry as many as six million bacteria on its feet.

Dr Simon Park, of the Department of Microbial and Cellular Sciences at the University of Surrey, said: "This exploration was inspired by the current hot weather and the theory that both flies and bacteria seem to benefit from it.

With higher temperatures you get more fly activity and more , they grow faster.

"The blue bottle fly, Calliphora vomitoria -the Latin name seems appropriate - is a very common and cosmopolitan insect, with which we share many of our environments.

A fly's bacteria track.

"This fly seems to be equally at home feeding on dead animals, faeces and our carefully prepared making it an unparalleled transmitter of transmitting disease.

"It prefers to swallow liquid food, and usually regurgitates ingested material in order to liquefy its meal and to facilitate digestion.

"In this manner flies can contaminate clean surfaces with approximately 0.1mg of food per landing. In addition, of bacteria rich may be deposited during feeding, about every four to five minutes."

Dr Park added "I trapped three blue bottle files in a large square plastic dish filled with solid bacterial growth media and allowed the flies to walk over the surface for just 10 minutes.

"As the flies travelled over the un-inoculated surface they left behind a trail of the bacteria in their footsteps. These tracks were at first invisible. However, after a day or so the bacteria grow into visible points or colonies that reveal the activity of the flies and the extent of their contamination.

"I must admit that even as a well-seasoned microbiologist, these images make me slightly queasy."

As for the flies they were not harmed in any way and let go to get on with their lives.

Dr Park's advice for this current spell of hot weather is to keep your food covered up to prevent landing on and to put food into your fridge wherever possible to prevent the growth of any harmful bacteria.

Fridges can struggle to maintain cold temperatures in this so check that yours is working efficiently.

Explore further: From bacteria to lions – how tiny proteins which control our responses to both could be linked

add to favorites email to friend print save as pdf

Related Stories

Stopping flies before they mature

Nov 26, 2012

An insect growth regulator is one of the latest technologies U.S. Department of Agriculture (USDA) scientists are adding to their arsenal to help fight house flies that spread bacteria to food.

Hunger affects decision making and perception of risk

Jun 25, 2013

Hungry people are often difficult to deal with. A good meal can affect more than our mood, it can also influence our willingness to take risks. This phenomenon is also apparent across a very diverse range ...

Bugs on Bugs

Aug 16, 2007

Bacteria — you can live without ’em, but it won’t do you any good, according to a study of fruit flies by USC College biologists.

Fruit fly's 'sweet tooth' short-lived, research finds

Oct 16, 2012

While flies initially prefer food with a sweet flavor, they quickly learn to opt for less sweet food sources that offer more calories and nutritional value, according to new research by University of British ...

New type of bacterial protection found within cells

Nov 13, 2012

UC Irvine biologists have discovered that fats within cells store a class of proteins with potent antibacterial activity, revealing a previously unknown type of immune system response that targets and kills bacterial infections.

Recommended for you

For resetting circadian rhythms, neural cooperation is key

16 hours ago

Fruit flies are pretty predictable when it comes to scheduling their days, with peaks of activity at dawn and dusk and rest times in between. Now, researchers reporting in the Cell Press journal Cell Reports on April 17th h ...

Rapid and accurate mRNA detection in plant tissues

18 hours ago

Gene expression is the process whereby the genetic information of DNA is used to manufacture functional products, such as proteins, which have numerous different functions in living organisms. Messenger RNA (mRNA) serves ...

For cells, internal stress leads to unique shapes

Apr 16, 2014

From far away, the top of a leaf looks like one seamless surface; however, up close, that smooth exterior is actually made up of a patchwork of cells in a variety of shapes and sizes. Interested in how these ...

User comments : 0

More news stories

Scientists tether lionfish to Cayman reefs

Research done by U.S. scientists in the Cayman Islands suggests that native predators can be trained to gobble up invasive lionfish that colonize regional reefs and voraciously prey on juvenile marine creatures.

Deadly human pathogen Cryptococcus fully sequenced

Within each strand of DNA lies the blueprint for building an organism, along with the keys to its evolution and survival. These genetic instructions can give valuable insight into why pathogens like Cryptococcus ne ...

Biologists help solve fungi mysteries

(Phys.org) —A new genetic analysis revealing the previously unknown biodiversity and distribution of thousands of fungi in North America might also reveal a previously underappreciated contributor to climate ...

Leeches help save woman's ear after pit bull mauling

(HealthDay)—A pit bull attack in July 2013 left a 19-year-old woman with her left ear ripped from her head, leaving an open wound. After preserving the ear, the surgical team started with a reconnection ...

Venture investments jump to $9.5B in 1Q

Funding for U.S. startup companies soared 57 percent in the first quarter to a level not seen since 2001, as venture capitalists piled more money into an increasing number of deals, according to a report due out Friday.