Creatures of the Amazon
Botfly

By Mike Collis

Horse botfly (Gasterophilus intestinalis)

When most people think of the Amazon they think of hot and humid jungles where creatures are lurking in the undergrowth, waiting to pounce as you pass by! Stories of giant Anacondas, man-eating Piranhas, Alligators and Jaguars have all helped to create the image of a "green hell", images exaggerated by travellerís stories over the years.

Early in the last century the English explorer Colonel Percy Fawcett talked about man-eating Piranhas and giant Anacondas on his travels in "Darkest Peru". One of his strangest stories was about natives making tutting sounds to encourage 1 inch long maggots to come out of the sores on a manís back. Was this true, or just another amazing amazon myth?

The truth is, yes it is true because the real danger in the rainforest comes from small insects and their associated danger of disease.

One of these insects that is particularly partial to human flesh is the botfly. The botfly looks like a common housefly and it has a bizarre life cycle. When a female botfly feels the need to produce more botflies she catches a mosquito or another flying insect. The smaller fly is firmly held by the botfly female and rotated to a position where the botfly attaches about 30 eggs to the body under the wings. When the mosquito is released and lands on a larger animal and starts to feed on its blood the body heat of the host animal induces hatching upon contact. As the mosquito feeds on the blood of a victim the botfly larvae imerge and move across to the new host, and starts to feed.

After a short time the small maggot starts to burrow into its hosts flesh on which it will feed and live until the time comes for a change of address. The larva, because of its spines, can pose an extremely painful sub-epidermal condition. Removal processes include placing raw meat, especially raw bacon over the airhole, which in theory will coax the larva out. Additionally, one can attempt to seal the breathing hole of the larva with nail varnish, super glue or vaseline and then, after a day, squeeze out the suffocated, dead larva. Use of sticky tape can work, but carries the additional risk of infection because portions of the larvaís breathing tube can be broken off by the tape and cause the remainder of the body to remain inside and start to decay. Instead of using these tactics to remove the embodied botfly some amazonian indians have other ways to remove the unwanted tenant. One way is to blow the smoke of the jungle tabacco called mapacho into the breath hole of the botfly. Apparently botflies do not like mapacho smoke and very soon vacate the premises, or so they say. Another way, so the local people say is to make tutting noises over the swelling, rather like an old lady making noises of disapproval. Apparently the botfly peeks out of its hole to investigate the noise, at which point you squeeze hard to eject the maggot. Whistling at the right pitch is also supposed to work and this is the basis of Colonel Fawcettís bizarre story.

After a while the unwelcomed guest settles down in his or hers new home. At this time the area starts to swell, it is a bit painful but your guest adds a bit of anaesthetic from glands in its mouth to reduce the pain. Now the home of your botfly resembles a boil with a hole in the middle. If the botfly has taken up residence on an accessible part of the body you will actually get to see your guest. To breathe the botfly waves an appendage out of the hole every now and again.

Some victims will squeeze the swelling in an attempt to eject the botfly, but success is unlikely. It is very difficult to get rid of a botfly before it wants to vacate the premises because of the spines that cover its body. So they then resort to poking things down the hole and pouring all kinds of preparations into the cavity to get rid of the intruder. But this creates a catch-22 situation, if you manage to kill the botfly you can end up with a dead maggot in an unpleasant festering wound. Not the most ideal situation to get into in the sticky and sweaty conditions of the rainforest. After six weeks the bump will grow to the size of a large grape and will ache due to the stretched skin. Victims can feel the botfly moving from time to time, a distinctly odd feeling, but it never hurts because of the anaesthetic.

After a little while longer the botfly must move on. He quietly drops out of his hole and buries himself in the soil and waits to change into a full grown botfly and the process starts all over again.

Be warned botflies also lay eggs on sweaty clothing left in the open overnight. If someone puts on a sweaty shirt the next day they could get more than they bargained for.

The Human Botfly, Dermatobia hominis, is the only species of Bot Fly known to parasitise humans routinely.
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