MadSci Network: General Biology |
Dear Emma,
Thank you for your question about Houseflies. Houseflies belong to a
group of flies called Filth Flies. Filth Flies get their names
because they are important for breaking down decaying material. Any
species that is important for breaking down dead organic material is
called a saprophyte. If their were no saprophytes, then there
would be no top soil for plants to grow in. Saprophytes, such as the
Filth
Flies, digest dead trees, dead animals, and even animal wastes, such as
feces. (It is mostly because they break down feces that Houseflies and
their cousins are called Filth Flies!)
It is the young fly (called a maggot) that lives as a saprophyte. When
you see a fly buzzing around, it is in its adult stage. As an adult, the
fly is important for providing food for insect-eating animals, such as
frogs. (To see the different stages of a housefly's life, see this picture
on the website of Clemson University. The white ones are the
maggots. West Virginia University has a web site that describes the life cycle, and many
other interesting facts about Houseflies.)
While most of the Filth Flies play a role in their natural ecosystems,
Houseflies are a little different. They are a single species (Musca
domestica) that has adapted to living off of human waste. This
includes not only the organic material in their houses and dumps, but also
the fecal waste of their animals, such as cattle. Because Houseflies,
unlike most Filth Flies, do not play a role in maintaining a natural
ecosystem, they are considered pests.
Other species that have adapted to live off of humans are certain species
of mosquitos (such as the Asian Tiger Mosquito named Aedes
albopictus) and certain roaches (such as the American Cockroach named
Periplaneta americana). These species, like the housefly, have
spread all over the world, wherever humans have gone. Not all flies (or
roaches or mosquitos) are human pests, and so people must be very careful
in using pesticides to kill all of one kind of insect in an area. It
would be very bad for natural ecosystems if all of the natural Filth Flies
were killed off!
Ecosystems are very interesting, and biologists spend their lives studying
why different species are important. It is great that you're already
thinking about how species fit in with their environments! Please write
again if you have any comments or questions!
John Carlson
MAD Entomologist
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