SEPTEMBER
2001

 

 

 

By
Tom Turpin
 
Professor of
Entomology
Purdue University

 

 

 

 

 

9-13-01

Little Fruit Flies Cause Big Disturbance

Fruit flies are not one of the largest insects in the world. But they are one of the best known. These little flies get their name from their association with fruit. There are two groups of fruit flies.

One group, which belongs to the scientific family known as Tephritidae, has immatures that feed on a variety of plant materials. Some that feed on fruits have become major agricultural pests. Two of the worst pests of this group are the Mediterranean fruit fly and the apple maggot.

The Mediterranean fruit fly, sometimes called the medfly, attacks over 250 kinds of fruits and nuts. The adult fly lays eggs under the skin of fruit. The eggs hatch into headless maggots that bore into the fruit pulp. The feeding destroys the fruit and may introduce bacteria or fungi that will cause the fruit to rot.

The medfly is native to South Africa, but like a lot of pest insects it has managed to find its way to other parts of the world. It is found throughout Europe, Central and South America, Australia and Hawaii. It has appeared in Florida and California several times. Each time the medfly was found in these states, it has been eradicated with attractants and chemical controls.

Unlike the medfly, the apple maggot, is a native insect. It probably originally fed on hawthorn before apples were grown in North America. It is a major pest of apples and must be controlled in most apple production areas.

While the medfly and apple maggot are major pests, most people don't worry a great deal about these insects. There are other fruit flies, however, which are encountered by most people on a regular basis.

These fruit flies are classified as Drosophilidae and are known as Drosophilia. They are also known as pomace flies and are generally seen near decaying fruit or other vegetation. Breweries and vinegar factories frequently harbor populations of these insects, which give rise to another common name, vinegar flies.

Most of us will see these pesky fruit flies when we have ripe fruit around the house. Fruit fly populations are especially high during the fall when a high volume of fruits and vegetables begin to rot on the tree or vine.

Getting rid of these little flies is a matter of getting rid of the ripe fruits and vegetables. My grandmother would just leave a couple of slices of melon or tomato in a bowl sitting in the kitchen overnight. The next morning she would place a dishtowel over the bowl and carry it and the captured flies outside!

Annoying though they may be, Drosophilia fruit flies have played an important place in scientific discovery. These insects are easy to produce in the laboratory and have been used to unlock the secrets of genetics. In fact, scientists have mapped the entire DNA code of the fruit fly Drosophilia melanogaster. Who cares, you ask? Well, humans and fruit flies share many genes, and many of the genes identified in the fruit flies are the same as genes linked to diseases in humans. So the secret to a healthier life for humans might be found in the lowly fruit fly.

In the meantime, I'll let the scientists raise their fruit flies if they want. I'll continue to swat those that try to share my slice of ripe breakfast muskmelon!

 

Writer: Tom Turpin
Editor: Olivia Maddox