Many people are familiar with the tsetse fly by name, but fewer are aware of the unique way in which tsetse flies give birth to their young. While most flies lay dozens or even hundreds of eggs, the birthing process of the tsetse fly is more akin to that of a mammal. In a fascinating video, a female tsetse fly is seen giving birth to one larva at a time, each nearly the size of her body. Unlike other insects that produce large batches of eggs that develop externally, female tsetse flies nurture their young individually inside their uterus. This rare process is seldom witnessed in the wild by humans, but scientists have been able to observe it in laboratory settings. Let’s delve deeper into the world of tsetse flies and their unique reproductive methods.
What is a Tsetse Fly?
Tsetse flies have a distinctive proboscis appendage on their heads.
Tsetse flies (Glossina morsitans) belong to the Glossinidae family and are biting flies that survive as obligate parasites by feeding on the blood of larger vertebrate animals. Their significant role in disease transmission has led to extensive scientific studies on tsetse flies. While they may resemble other large flies, tsetse flies have a habit of folding their wings across their abdomens when at rest. They also feature an elongated proboscis appendage protruding from their heads. Tsetse flies are resilient creatures, unlike other large flies that are easily swatted with a flyswatter. They are commonly found in Africa between latitudes 15° north and 20° south, primarily inhabiting woodlands but venturing into open grasslands to feed on host animals. Blood serves as their primary source of sustenance, with tsetse flies feeding almost daily. While different species of biting flies are active at varying times of the day, tsetse flies typically become less active after sunset. Male tsetse flies tend to feed on humans, while females prefer larger game, possibly due to the greater nourishment needed for their unique birthing process.
How Do Tsetse Flies Reproduce?
Female tsetse flies give birth to one larva at a time in a unique process.
Female tsetse flies usually give birth eight times throughout their lifespan, with each birth occurring individually and the developing young making up a significant portion of the mother’s body size. This is because tsetse offspring undergo internal development during the initial three larval stages through a process known as adenotrophic viviparity. The larvae feed on a milky substance produced by a modified gland in the mother’s uterus during this period, which lasts between four and ten days, enabling them to share resources with their mother. Once they reach a considerable size, sometimes even surpassing their mother’s mass, the larvae are born, as demonstrated in the video. Subsequently, the larvae burrow into the ground and form a
The presence of tsetse flies can have a significant impact on both humans and animals. These flies feed on a variety of hosts, including antelopes, buffalo, bush pigs, and red river hogs. They are also known to feed on humans, which has led to the transmission of diseases. Tsetse flies can transmit parasites known as trypanosomes while feeding, causing diseases such as sleeping sickness in humans and nagana in livestock. Symptoms of sleeping sickness in humans include fevers, joint pain, headaches, numbness, confusion, coordination issues, and insomnia. If left untreated, sleeping sickness can be fatal and affects hundreds of people each year. Tsetse flies have a unique gestation and birthing process, with larvae feeding on their mother’s blood. This parasitic diet has significant consequences for human and livestock populations. To learn more about tsetse flies and their unique reproductive process, watch the video “The Bizarre Reason Tsetse Flies Don’t Lay Eggs” on A-Z Animals.
