Why do insects like houseflies (and some others) fly round and round
in a very small area, for hours at a time?  I'm talking about the
behaviour pattern where you observe a fly in a room, and it just goes
round and round (in triangle
or square patterns) in a two-foot-square area. The area is so small, i
don't see how they can be looking for food that way, and
surely it's a waste of energy?  Nor is it to do with temperature -
these are rooms with a very similar temperature throughout (not
directly sunlit, etc.)  So what is the point of this flying
behaviour?  Or if you like, what evolutionary advantage is the fly
gaining by doing this - instead of say, flying in straight lines
through an environment?
I have researched this on the net but although there is plenty on
mechanisms of flight and navigation, I can't find out what this
behaviour is all about.  Thanks,.

hi joshua4321,

Both Sciencenet.org and The Knowledge Explosion Network (KEN) contain
a wealth of information on science related matters. Both sites contain
answers to specific questions about fly behaviour, which have been
answered by experts.

According to Sciencenet.org, flies fly round and round because they
are searching for a perch (e.g. a central light fitting) as it is the
best position to fight off a rival and for attracting a mate.
http://www.sciencenet.org.uk/database/Biology/Original/b00126d.html

The Knowledge Explosion Network (KEN) explains why flies are attracted
to light bulbs, which you also may find relevant. According to KEN,
flies (and other flying insects) usually prefer warm spots, and they
tend to fly around a light bulb and burn up less nutrients. A normal
light bulb uses 70% of its energy to produce warmth. Insects sense the
infra-red radiation and try to get near the source. They cannot land
on the bulb, or they will die, but when the light bulb is switched
off, it still emits warmth. Thus the insects still fly towards it.
http://www.theken.org/browser_viewquestion.php?questionID=196

Keywords used
"why do flies"

hope this helps

---

Request for Answer Clarification by joshua4321-ga on 03 Nov 2002 14:11 PST

Thanks for your prompt response.  Interesting, but you can certainly
observe behaviours that don't fit these bills.  I've often seen a fly
going round in identical circles, near obvious perches (wall nooks,
ceiling) but without settling on them.  And nowhere near lightbulbs,
warm or otherwise.  Since the circles are more or less identical i
don't see what the fly is gaining by doing this - in terms of any
search (for perch, mate, food, warmth etc.)     So I'm not sure the
question has really been answered...

can you find out any more?   

Thanks very much

---

Clarification of Answer by jackburton-ga on 04 Nov 2002 04:05 PST

Yes, I know exactly what you mean. I have also observed this
monotonous behaviour in flies, and it has made me wonder too! Myself,
I was particularly interested to know why the flies in my kitchen can
sit perched on a light bulb for so long, but now I know. I have also
noticed lately how a fly can change its flying behaviour dramatically
when it chases off (or chases after?) another fly in its space, so the
first part of my original answer would seem to be relevant your
question. However, I agree with the comments you raised in your
clarification request, so it would seem that there's a bit more to it.
I came across an answer to a trivia question - "What is the difference
between flies and wasps?"... which I believe addresses your question,
as it talks about how insects are categorised according to the number
of wings it has and what role the fly's wings play during flight:
"One of the most basic groupings in the Class Insecta is the "Order".
Orders are generally named for the type of wings an insect has...
[Flies]...have two flying wings and two reduced wings. The reduced
hind wings of flies are called halteres . They are used for balance
during flight. They spin around in little circles and keep the fly
from flipping over and over as it flies. They serve a similar purpose
to the propeller on the tail of a helicopter. If a helicopter didn't
have that little propeller, it would just spin round and round. So
flies, like all winged insects (some species never get wings, but most
do), really do have four wings!"
<Source: BUGMAN Bug Trivia Quiz (What is the difference between flies
and wasps? answered by Mark Berman)>
http://bugs1.netfirms.com/bugs/BUGQuiz/answers/Flies_and_wasps.shtml 
BUGMAN Educational Entoprises (B.E.E.) was founded by Mark Berman who
obtained an Entomology B.Sc. from the University of Hawaii at Manoa,
and Secondary General Science and Biology Teaching Certification from
The Ohio State University. Berman started B.E.E., after extensive
volunteer experience in classrooms at all levels in Hawaii, Ohio, and
Massachusetts, teaching with the Massachusetts Audubon Society, and
serving as the Curator of Entomology at the New England Science
Center. B.E.E. started in central Massachusetts and served most of New
England, primarily the greater Boston area. An Advisory Board has been
informally established and has shared information, talents, and ideas.
Current AB members are: Michele Bennett (currently in Tucson, AZ), Dr.
Wayne Hunter (currently in Orlando, FL), and Brian Foy (currently in
New York City).
---------------------------------------
I hope this has solved your curiosity.
If  you need more information on this you can email "Mark Berman" who
welcomes bug-questions!
Email: PR_the_expert@bugs.org
http://askanexpert.com/
http://bugs1.netfirms.com/bugs/contact.shtml

tricky question not answered precisely but opened interesting avenues of research.