US Federal List: no special status
CITES: no special status
Dermatobia hominis reach sexual maturity soon after emergence from the puparium, and viable eggs may be laid as of the second day of adulthood. An egg, after being glued onto a paratenic host for transport to the vertebrate host requires 5-9 days to develop, after which it requires an additional 27-128 days to pass through the three larval stages inside the definitive host. Normally, about 12, 18, and 12 days are required for a larva to pass through the first, second, and third instars respectively. At the end of the larval period, the third larval instar exits the definitive host's body and drops onto the soil, after which it burrows deeply into the soil or other available debris and pupates within a period of 2-3 days. At the end of the pupation period, which takes somewhere between 27-78 days depending on seasonal variation in soil temperature, the adult emerges and becomes sexually active within two hours.
Development - Life Cycle: metamorphosis
Infestation by D. hominis maggots, a form of myiasis, is a common condition in both humans and domesticated animals. It has been said that they surpass all other cuterebrines in terms of economic and public health importance. Dermatobia hominis larvae parasitize diverse regions on the human body, from the ankle to the brain of infants (through fontanelles, or gaps between incompletely formed bones of an infant's cranium) often causing tissue damage and bouts of severe pain from the boring activity of the larvae. In rare cases, fatalities have resulted, particularly from cerebral myiasis. Furthermore, lesions, or warbles, caused by the infestation may lead to secondary infections, which, if not treated with antibiotics, may result in fatality or other health complications. Treatment is by removal of larvae. Care must be excercised in doing so, since the larvae anchor themselves into the flesh using the spines on their tegument. Rupturing of larvae as the result of improper removal may lead to severe infection.
Although D. hominis infestation occurs among a broad range of domesticated animals, from dogs to sheep, their negative effects on the cattle industry is most severe in areas of the Neotropics. As a single animal may concurrently be infested by upwards of thousands of maggots, it is not suprising that losses have resulted from cattle mortality, from the rendering of the animal as unfit for slaughter, and from the destruction of the animal's hide. Negative impacts had been strong enough to cause a cessation in herding operations in Panama.
Negative Impacts: injures humans (bites or stings, causes disease in humans ); causes or carries domestic animal disease
Due to their unique egg dispersal strategy using mobile porters, D. hominis host range is more generalized than other bot-fly species. They have been found to parasitize many warm-blooded vertebrates and some birds (e.g., toucans and turkeys). And as suggested by the name, human bot fly, humans also frequently serve as hosts.
Ecosystem Impact: parasite
Like other species in the family Oestridae, adult D. hominis are non-feeding.
Larvae are endoparasites of birds and mammals. They bore into the skin of their hosts, either through pre-existing lesions in the skin or through active piercing, and become established in the subcutaneous layer. Breathing air through their posterior spiracles and employing body spines as anchors, D. hominis larvae use their sclerotized mouthparts to bore deeper into the host's body as they feed and grow on host tissue exudates. Feeding location on the host is not specific, as larvae have been found to establish at almost any exposed surface of the host's body, from the scrotum to the eye, although more frequently at more exposed regions of the body such as the leg and the back.
Animal Foods: body fluids
Primary Diet: carnivore (Eats body fluids)
Dermatobia hominis are endemic to the highlands of Central and South America. Their range extends from southern Mexico to northern Argentina.
Biogeographic Regions: neotropical (Native )
Dermatobia hominis, also known as the tropical warble fly or human bot fly, are found in tropical and semi-tropical areas of the New World. These places are typically coffee-growing highlands, as D. hominis prefer hilly, moist, and cool secondary-forests.
Habitat Regions: tropical ; terrestrial
Terrestrial Biomes: rainforest ; scrub forest
Other Habitat Features: agricultural
Adult D. hominis are 12-18 mm in length, are bluish in color, and resemble bumble-bees. They have three ocelli and a pair of large compound eyes, which are sexually dimorphic in that eyes are situated closer together in males than in females. Also, females are normally larger in size than males and bear a pseudovipositor at their posterior. As in other muscomorphans, the antennae of adult D. hominis each bear an arista -a tenuous, plumose projection- on the second of its three segments. The knob-like halteres, or functionally reduced hind-wings that are characteristic of dipterans, are also present. Peculiarly, the ancestral mouthparts have been lost in adult D. hominis, as well as in other cuterebrines.
Dermatobia hominis larvae, or maggots, are identified by the pyriform shape, the transverse rows of spines on their tegument, sclerotized mouthparts, and the pair of projecting spiracles at the posterior end. They may reach 25 mm in length and 7 mm in diameter.
Range length: 12 to 18 mm.
Other Physical Features: ectothermic ; heterothermic ; bilateral symmetry
Sexual Dimorphism: female larger; sexes shaped differently
Mating in D. hominis begins with "pouncing" displays performed by a male in response to sexual readiness in a female, which is indicated by the protraction of the latter's abdomen or pseudovipositor. Copulation is normally contingent upon female receptiveness; in other words, females seem to exhibit behavior suggestive of mate choice. Laboratory experimentation has revealed that males can pair with multiple mates in the average ratio of 1 male to 2.8 females. Perhaps due to the polygynous mating system, competition among males has been observed in the form of "pouncing" disturbances directed at copulating pairs. Copulation terminates after about 9 minutes.
Mating System: polygynous
Dermatobia hominis exhibit a homometabolous life-cycle. Being non-feeding and having a short adult life span (3-4 days in the laboratory), this stage in the life-cycle of D. hominis is allocated primarily towards reproductive efforts. Females lay 800 to 1,000 eggs.
Unique from other bot-fly species, which lay their eggs directly on the host or in the host's environment, is the peculiar egg dispersal strategy exhibited by females of the human bot fly; this process involves the use of porters (i.e., paratenic hosts) as vectors for transporting eggs onto the bodies of the vertebrate hosts. Under this strategy, a female captures a porter and glues her eggs onto one side of its abdomen using a water-insoluble glue, after which the porter is released without being harmed. Being sensitive to a sudden rise in temperature, the eggs instantly hatch upon contact with the warm-blooded body of a definitive host as the porter lands onto it, usually to feed on blood. Within 5-10 minutes, the larvae bore their way into the definitive host's body, often via the wounds inflicted by the porter's feeding, and establish themselves in the subcutaneous layer. Forty-eight species of flies--of which about half are mosquitoes--and a tick are reported to be involved in this paratenic relationship with female D. hominis. Porter species are often zoophilous, diurnal, moderate in size, and not too active. Potential advantages of this egg dispersal strategy include the protection of eggs from the elements and egg-parasitism, the prevention of egg loss from host grooming, and the adaptive allocation of energy in reproductive efforts.
Range eggs per season: 800 to 1000.
Key Reproductive Features: semelparous ; sexual ; fertilization (Internal ); oviparous
Myiasis is infection with the larval stage (maggots) of various flies. Flies in several genera may cause myiasis in humans. Dermatobia hominis (Diptera: Oestridae) is the primary human bot fly; its distribution ranges from Mexico into South America. Chrysoma bezziana (Diptera: Calliphoridae) is the Old World screwworm and Cochliomyia hominovorax (Diptera: Calliphoridae) is the primary screwworm fly in the New World. Cordylobia anthropophaga (Diptera: Calliphoridae) is known as the tumbu fly. Flies in the genera Cuterebra (Diptera: Oestridae), Oestrus (Diptera: Oestridae) and Wohlfahrtia (Diptera: Sarcophagidae) are parasites of other animals that also occasionally infect humans.
Adults of the Human Bot Fly (Dermatobia hominis) are free-living flies. Adults capture blood-sucking arthropods (such as mosquitoes) and lay eggs on their bodies, using a glue-like substance for adherence. Bot fly larvae develop within the eggs, but remain on the vector until it takes a blood meal from a mammalian or avian host. Newly-emerged bot fly larvae then penetrate the host's tissue. The larvae feed in a subdermal cavity for 5-10 weeks, breathing through a hole in the host's skin. Mature larvae drop to the ground and pupate in the environment. Larvae tend to leave their host during the night and early morning, probably to avoid desiccation. After approximately one month, the adults emerge to mate and repeat the cycle.
The human botfly, Dermatobia hominis (Greek δέρμα, skin + βίος, life, and Latin hominis, of a human), is a species of botfly whose larvae parasitise humans (in addition to a wide range of other animals, including other primates[1]). It is also known as the torsalo or American warble fly,[1] though the warble fly is in the genus Hypoderma and not Dermatobia, and is a parasite on cattle and deer instead of humans.
Dermatobia fly eggs have been shown to be vectored by over 40 species of mosquitoes and muscoid flies, as well as one species of tick;[2] the female captures the mosquito and attaches its eggs to its body, then releases it. Either the eggs hatch while the mosquito is feeding and the larvae use the mosquito bite area as the entry point, or the eggs simply drop off the muscoid fly when it lands on the skin. The larvae develop inside the subcutaneous layers, and after about eight weeks, they drop out to pupate for at least a week, typically in the soil. The adults are large flies lacking mouthparts (as is true of other oestrid flies).
This species is native to the Americas from southeastern Mexico (beginning in central Veracruz) to northern Argentina, Chile, and Uruguay,[1] though it is not abundant enough (nor harmful enough) to ever attain true pest status. Normally the greatest risk they pose to humans is increasing the chances of infection due to creating an open wound for their breathing holes. Since the fly larvae can survive the entire eight-week development only if the wound does not become infected, patients rarely experience infections unless they kill the larva without removing it completely.
The easiest and most effective way to remove botfly larvae is to apply petroleum jelly over the location, which prevents air from reaching the larva, suffocating it. It can then be removed with tweezers safely after a day. White glue mixed with pyrethrin or other safe insecticides and applied to the spot of swelling on the scalp will kill the larvae within hours, as they must keep an air hole open, so will chew through the dried glue to do this, consuming the insecticide in the process.
Venom extractor syringes can remove larvae with ease at any stage of growth. [3] A larva has also been successfully removed by first applying several coats of nail polish to the area of the larva's entrance, weakening it by partial asphyxiation.[4] Covering the location with adhesive tape would also result in partial asphyxiation and weakening of the larva, but is not recommended because the larva's breathing tube is fragile and would be broken during the removal of the tape, leaving most of the larva behind.[4]
Oral use of ivermectin, an antiparasitic avermectin medicine, has proven to be an effective and noninvasive treatment that leads to the spontaneous emigration of the larva.[5] This is especially important for cases where the larva is located in inaccessible places such as inside the inner canthus of the eye.
The human botfly, Dermatobia hominis (Greek δέρμα, skin + βίος, life, and Latin hominis, of a human), is a species of botfly whose larvae parasitise humans (in addition to a wide range of other animals, including other primates). It is also known as the torsalo or American warble fly, though the warble fly is in the genus Hypoderma and not Dermatobia, and is a parasite on cattle and deer instead of humans.
Dermatobia fly eggs have been shown to be vectored by over 40 species of mosquitoes and muscoid flies, as well as one species of tick; the female captures the mosquito and attaches its eggs to its body, then releases it. Either the eggs hatch while the mosquito is feeding and the larvae use the mosquito bite area as the entry point, or the eggs simply drop off the muscoid fly when it lands on the skin. The larvae develop inside the subcutaneous layers, and after about eight weeks, they drop out to pupate for at least a week, typically in the soil. The adults are large flies lacking mouthparts (as is true of other oestrid flies).
This species is native to the Americas from southeastern Mexico (beginning in central Veracruz) to northern Argentina, Chile, and Uruguay, though it is not abundant enough (nor harmful enough) to ever attain true pest status. Normally the greatest risk they pose to humans is increasing the chances of infection due to creating an open wound for their breathing holes. Since the fly larvae can survive the entire eight-week development only if the wound does not become infected, patients rarely experience infections unless they kill the larva without removing it completely.
Extracted human botfly larva: The arrow points to the larva's mouthparts.
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