What are Tsetse Flies?

Mary McMahon
Mary McMahon

Tsetse flies are bloodsucking flies in the genus Glossina. These African natives are probably most famous for the trypanosomes that they carry; these pathogens can cause a variety of illnesses, most notably sleeping sickness, a disease which is characterized by extreme lethargy, leading to coma and death if not treated. Tsetse flies also have a few interesting biological traits which make them a topic of study for people in the scientific community.

Tsetse flies can cause sleeping sickness, a disease which can lead to coma and death if not treated.
Tsetse flies can cause sleeping sickness, a disease which can lead to coma and death if not treated.

A typical tsetse fly has a yellow to brown body, depending on the species, and is generally larger than a housefly. At rest, tsetse flies fold their wings over each other, a distinctive trait which makes them very easy to identify. The flies also have unusually long proboscises, which are used to suck blood from their prey. Other features of the tsetse fly, like their hairy antennae, are a bit harder to identify in the field.

Flies start out as maggots, like butterflies start out as caterpillars.
Flies start out as maggots, like butterflies start out as caterpillars.

The life stages of the tsetse fly are quite interesting. The females actually incubate the larvae inside themselves until they reach the third instar stage, at which point they burst out and pupate underground, developing into adult tsetse flies within a matter of hours. While the females incubate the young, they feed them with a secretion much like milk which is presumably derived from their blood-rich diets.

Tsetse flies can be a pest to livestock.
Tsetse flies can be a pest to livestock.

These flies are famous for feeding indiscriminately on the blood of other animals. Many tsetse flies actually favor reptiles, although they are perfectly happy drinking the blood of mammals as well. In all instances, the flies can pass an assortment of diseases through their blood; the parasitic trypanosomes which cause sleeping sickness can actually live in the body of a tsetse fly. In animals, sleeping sickness is known as nagana; both human and animal versions are treatable with drugs.

As a general rule, tsetse flies favor areas of high humidity with dense vegetation. In parts of Africa where tsetse flies are endemic, many people have adapted their lifestyles to avoid the fly. For example, farmers may stick to the cooler, drier uplands to reduce the risk of exposure, and livestock are pastured on higher ground as well. Travelers in areas with tsetse fly populations are typically advised by regional governments to take precautions such as sleeping under an insect net.

Incidentally, tsetse means “fly” in Tswana, an African language. As a result “tsetse fly” is a bit of a redundant statement, and some biologists prefer to drop the “fly” altogether when discussing tsetses.

Sleeping sickness caused by tsetse flies can cause extreme lethargy.
Sleeping sickness caused by tsetse flies can cause extreme lethargy.
Mary McMahon
Mary McMahon

Ever since she began contributing to the site several years ago, Mary has embraced the exciting challenge of being a wiseGEEK researcher and writer. Mary has a liberal arts degree from Goddard College and spends her free time reading, cooking, and exploring the great outdoors.

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Discussion Comments


@allenJo - Yes, I believe that the fly can be a carrier for any disease. It can contract diseases from one host and transmit them to another.

What makes it particularly harmful is that some diseases can remain dormant for quite some time. This makes it impossible to treat them right away, since you don’t know you’ve been infected.


@nony - I wonder if AIDS can be carried by this fly in addition to usual tsetse fly disease? I think this would make it fatal, although sleeping sickness is certainly fatal enough from what I’m reading in the article.


While the article doesn’t say, my guess is that the tsetse fly probably doesn’t respond to the usual insect repellants you would use for the typical household fly.

There may be specialized sprays for it. But since these infestations affect entire regions my guess is that there is some kind of widespread tsetse fly control program that developers implement.

Maybe they use crop duster airplanes to spread a region that is filled with these insects to make sure that they are thoroughly wiped out before developing the region. They probably try to immunize their vital livestock too so that they can remain resistant to any few stray flies here or there.


@julies - Your comment reminds me of many pictures I have seen of undernourished children from Africa who have flies on their faces.

It makes me wonder if these are tsetse flies. It would be interesting to know how many children get this tsetse fly African sleeping sickness every year.

If they live in conditions where the tsetse flies are endemic, they probably don't have access to the proper care and medicine that is needed to treat this sickness.


I never realized that flies could carry such diseases for humans and animals. For me, I just saw them as pesky creatures who were annoying.

We have horses, so always get more than our share of flies. I have always called them horse flies, because they are much bigger than the regular house flies.

We spray them for flies in the summer, but this is more for their comfort than worrying about the flies giving them any kind of disease.

I am sure our horses are glad when the first frost comes and they aren't bothered with these flies for the rest of the winter.

It makes you wonder how the people who don't have a choice to escape the African tsetse fly deal with it on a daily basis. We live in enclosed, air conditioned houses and only have to worry about one or two flies getting in the house.

If you had to live with these flies every day, it would not only be annoying, but also harmful to your health.

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