What are Tsetse Flies?

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.

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.

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.

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.

Tsetse flies are bloodsucking insects primarily found in sub-Saharan Africa. They inhabit rural areas, living in woodland and savannah regions near water sources. These flies are vectors for trypanosomes, the parasites responsible for causing African trypanosomiasis, also known as sleeping sickness in humans and nagana in animals.

Tsetse flies transmit diseases through their bite. When they feed on the blood of an infected host, they pick up trypanosomes, which multiply within the fly. After about three weeks, the fly can transmit the parasites to new hosts, continuing the cycle of infection. The disease transmission is particularly concerning for both human health and livestock productivity.

Sleeping sickness begins with fever, headaches, joint pains, and itching. As the disease progresses, neurological symptoms appear, including changes in behavior, confusion, sensory disturbances, and poor coordination. In its advanced stage, it leads to daytime sleepiness with nighttime sleep disturbances, hence the name 'sleeping sickness', and can be fatal if untreated.

Tsetse flies are endemic to Africa and are not naturally found in other continents. Their habitat is limited to the African region between the Sahara Desert and the Kalahari Desert. Efforts to control their population and prevent the spread of disease are focused within these geographical boundaries.

Control methods for tsetse fly populations include insecticide-treated cattle, aerial spraying, the use of insecticide-impregnated traps and targets, and the sterile insect technique (SIT). SIT involves releasing sterilized male flies to reduce breeding success. These methods aim to reduce the prevalence of the flies and the associated spread of trypanosomiasis.

For those in tsetse fly-infested areas, preventive measures include wearing long-sleeved shirts and pants in neutral colors, using insect repellent, and avoiding bushy areas during peak fly activity times. Tourists are advised to stay in well-screened or air-conditioned accommodations and to be vigilant about protective measures to reduce the risk of bites.