Courses for Kids
Free study material
Offline Centres


Last updated date: 01st Mar 2024
Total views: 298.2k
Views today: 7.98k
hightlight icon
highlight icon
highlight icon
share icon
copy icon

What is a botfly?

Botfly meaning the most highly developed group of mammalian obligate myiasis parasites. In the Oestridae, they are divided into four subfamilies. The Cuterebrinae, or New World skin bot flies, are the most primitive. Botflies, also known as warble flies, heel flies, and gadflies, are members of the Oestridae family of flies. Their larvae are mammalian internal parasites, with some species developing in the host's flesh and others in the intestine. Dermatobia hominis is the only species of botfly known to habitually parasitize people, while other flies induce myiasis in humans. A botfly, sometimes known as a bot fly, a bott fly, or a bot fly in different combinations, is any fly of the Oestridae family. Their life cycles differ widely across species, but all larvae are internal parasites of mammals. They are also known as warble flies, heel flies, and gadflies, depending on the species. Some species' larvae develop in the flesh of their hosts, while others develop within their hosts' alimentary systems.

The Hypodermatinae, or Old World skin bot flies, are their equivalents. The nose bot flies belong to the Oestrinae family, and they are thought to have originated in Africa. The Gasterophilinae subfamily, which includes stomach bot flies, appears to have developed in Africa as well.

In this context, the term "bot" refers to a maggot. A warble is a skin lump or callus produced by an ill-fitting harness or the presence of a warble fly larva underneath the skin. The human botfly, Dermatobia hominis, is the only species of botfly whose larvae normally parasitize people, while flies from other families cause human myiasis on occasion and are occasionally more dangerous. Cuterebra fontinella, often known as the mouse botfly, parasitizes tiny animals across North America. The botfly will use a mosquito to implant the eggs into the host. All four of these subfamilies have previously been classified as families and have been handled as such in the literature. As third-instar larvae, the subfamilies of Oestridae may be distinguished by their overall appearance and the shape of their caudal spiracular apertures. 

All four of these subfamilies have previously been classified as families and have been handled as such in the literature. As third-instar larvae, the subfamilies of Oestridae may be distinguished by their overall appearance and the shape of their caudal spiracular apertures. Although there are exceptions in subtropical and tropical climates, cuterebrines normally overwinter as diapausing pupae free of the host.

Family Oestridae

As subfamilies, the Oestridae presently include the previous families Oestridae, Cuterebridae, Gasterophilidae, and Hypodermatidae. The Oestridae are a subfamily of the superfamily Oestroidea, which also includes the families Calliphoridae, Rhinophoridae, Sarcophagidae, and Tachinidae. The Oestridae family of flies that cause myiasis has the greatest number of species whose larvae live as obligatory parasites within the bodies of mammals. There are over 150 species recognized globally. The majority of the other insects implicated with myiasis are from similar families, such as blow-flies. 

Larvae of flies belonging to the families Oestridae, Calliphoridae, and Sarcophagidae feed on dead or living animal tissues, evolving from first to second and third instar larvae within the Oestroidea superfamily (L1, L2 and L3). Some of these larvae produce infestations known as myiases as a result of their feeding on and infesting living tissues (Colwell et al., 2006). While larvae of the Calliphoridae and Sarcophagidae can feed on both dead and live tissues, creating facultative myiases and being of forensic interest, the Oestridae comprises flies whose larvae solely induce obligatory myiases. There are over 150 species in the Oestridae family, and their larvae parasitize a wide range of animals, from mice to elephants. 

As a result of a long-term adaptation to the host, they show a high degree of host specificity, and their biological life cycle may be exceedingly complicated (Otranto, 2001). Gasterophilinae, Oestrinae, Hypodermatinae, and Cuterebrinae are the four sub-families of medicinal and veterinary relevance. The Oestrinae subfamily has nine genera and 34 species (also known as nose flies), the Cuterebrinae subfamily has six genera and 83 species, and the Hypodermatinae subfamily has six species of the genus Hypoderma that are of important veterinary interest (Russell et al., 2013).


Bot fly eggs are laid on hosts or, in the case of D. hominis, employ an intermediary vector such as the common housefly, mosquitoes, or a tick species. The female botfly grabs the phoretic bug after mating by clinging onto its wings with her legs. She then creates the slip, attaching 15 to 30 eggs to the abdomen of the bug, where they incubate. The fertilized female repeats this process in order to spread the 100–400 eggs she makes during her brief adult stage of 8–9 days. Larvae from these eggs are activated by the warmth and closeness of a big animal host and burrow underneath its skin. Because many animal hosts sense the approach of a botfly and flee, intermediate vectors are frequently utilized. 

The eggs are directly deposited on the skin of bigger animals, or the larvae hatch and drop from the eggs connected to the intermediate vector; the body heat of the host animal encourages hatching upon contact or close proximity. Some botfly species can be found in the digestive tract after being ingested by licking. Myiasis can be caused by larvae burrowing into the host animal's skin (or tissue lining). Mature larvae exit the host and finish the pupal stage in the soil. They are real parasites since they do not harm the host animal. Equestrian caregivers face periodic challenges with equine botflies, which lay eggs on the insides of horses' front legs, the cannon bone and knees, and, depending on the species, the throat or nose. 

To prevent infection in the horse, these eggs, which resemble little yellow droplets of paint, must be carefully removed throughout the laying season (late summer and early fall). When a horse brushes its nose against its legs, the eggs are carried to the mouth and then to the intestines, where the larvae mature and adhere to the stomach lining or the small intestine. The larvae's adhesion to the tissue causes moderate irritation, resulting in erosions and ulcerations at the location. The removal of the eggs (which stick to the host's hair) is difficult since the bone and tendons on the cannon bones are immediately beneath the skin; eggs must be retrieved with a sharp knife (typically a razor blade) or abrasive sandpaper and captured before they fall to the ground. The larvae remain connected to the host for 10–12 months until passing out in the faeces. 

What is botfly larvae? Horse owners occasionally report spotting botfly larvae in horse dung. These botfly larvae have a cylindrical form and a reddish-orange colouration. Adult botflies emerge from growing larvae after one to two months, and the cycle begins again. Botflies can be managed using dewormers such as dichlorvos, ivermectin, and trichlorfon. The sores generated by these flies in calves can get infected with Mannheimia granulomatis, a bacteria that causes lechiguana, which is characterized by rapid-growing, hard lumps underneath the animal's skin. An infected animal will die within 3–11 months if antibiotics are not administered. The human botfly, Dermatobia hominis, occasionally utilizes people as a host for its larvae.

As Human Body

During the butchery of animals in frigid locations sustaining reindeer or caribou-reliant people, vast amounts of Hypoderma tarandi (caribou warble fly) larvae are accessible to human communities.

"The Inuit - Survivors of the Future," the sixth episode of season one of the television series Beyond Survival, shows survival expert Les Stroud and two Inuit guides hunting caribou on the northern shore of Baffin Island in Pond Inlet, Nunavut, Canada. Numerous larvae are seen on the interior of the caribou fur after skinning and slaughtering one of the animals. Stroud and his two Inuit guides each eat one larva (although grudgingly), with Stroud remarking that the larva "tastes like milk" and was previously widely ingested by the Inuit people.

Numerous works of art going back to the Pleistocene epoch in Europe attest to their consumption in premodern times as well. Hullin 67b of the Babylonian Talmud examines whether the warble fly is kosher.

More about Bot Fly

Gasterophilus, a significant horse pest, is represented by horse bot flies (subfamily Gasterophilinae). The adult horse fly, also known as a gadfly, lays 400 to 500 eggs (nits) on the forelegs, nose, lips, and body of the horse. Until the horse licks itself, the larvae stay in the eggs. The larvae emerge and are swallowed as a result of the wetness and friction stimuli. They adhere to the horse's stomach or gut lining and get all of their nutrition and oxygen from the horse's alimentary canal. After 8 to 11 months, the larvae reach maturity and are expelled through faeces. 

Young larvae of warble flies (Hypoderma lineatum and H. Bovis; subfamily Hypodermatinae) enter bovine skin and move through the body for several months before resting underneath the skin of the animal's back.

Each larva produces a distinct lump, known as a warble, from which a cow grub emerges. The grub develops into a pupa, then a fly, which lays additional larvae. The North American and European deer nose bot flies (Cephenemyia) and the sheep bot fly (Oestrinae) are members of the Oestrinae subfamily (Oestrus ovis). Blind stagger is a neurological ailment caused by active larvae deposited in sheep's nostrils. Oestrinae members are known for their quick flight, which may reach speeds of 20–30 kilometres (approximately 12–19 miles) per hour. Cuterebra cuniculi, which infects rabbits, and Cuterebra emasculator, which targets the scrotum of squirrels and sometimes emasculates them, belong to the Cuterebrinae subfamily of rodent bot flies. The human bot fly is a parasitic insect that feeds on cattle, deer, and people. The female attaches her eggs to mosquitoes, stable flies, and other insects, which then transport the eggs to their intended host. 

The eggs hatch when the body is heated, and the tiny larvae enter the skin. Dermatobia is responsible for the loss of meat and hides in tropical America. Botflies are distinct from other myiasis producers in a number of respects. To begin with, the grownups do not eat or absorb nutrition. They are unable to eat since they have just primitive, nonfunctional mouthparts. Water is probably the only fluid consumed by those with functional mouthparts and an accompanying alimentary tract to maintain an internal fluid balance. Second, bot flies are either very host-specific or parasitize just a limited set of closely related hosts. Although certain bot fly maggots can be found on unusual hosts, vulnerability to bot fly maggots does not always suggest fitness for normal or successful bot fly development.

FAQs on Botfly

1. How Does a Bot Fly Reproduce?

Answer: Female botflies deposit eggs on blood-sucking arthropods like mosquitoes or ticks to reproduce. When afflicted arthropods attack a person or another mammal, they deposit larvae from the eggs. A botfly larva burrows into subcutaneous tissue after entering the host's skin through a bite wound or a hair follicle.

2. Is it Possible for Bot Flies to Murder Humans?

Answer: Botflies do not kill their hosts in the majority of situations. However, the discomfort caused by the larvae can occasionally result in skin ulceration, which can lead to infection and death.

3. How Long Can a Botfly Stay in the Body of a Human?

Answer: The larvae within the host live for five to twelve weeks on average (Acha and Szyfres 1994). Tissue exudates are the larvae's food (Haruki et al. 2005 and Kahn 1999).