What do houseflies really like?

[rjb]

Joseph C. Tallon wrote in message <379898FD.8AB3DCE4 at Netxn.com>...
>Thank you Steven If I know the source of the adults (rotting tissue not
>garbage)  and the source of what is attracting
>the adults (rotting tissue or gas leak) then I can eliminate the
>infestation by removing these.
(deleted stuff)
>"Steven M. Cohen" wrote:
(deleted lots)
 
>> I am only guessing here, but decaying flesh gives off gasses [odors]
which
>> calliphorids probably use to home in on their meals.  These bugs most
likely
>> detect fuel gas in much the same way, and expect a nice ripe carcass near
>> gas leaks.  All gasses of the type we are talking about have several
>> elements in common, including hydrogen, oxygen and carbon.  It's been too
>> long since I've looked at organic chemistry, so I'll stop here before I
>> mis-classify something.  Hopefully a chemistry buff will come to the
rescue.
>> Let me know what your research uncovers.  Good luck.
 
Well, I am no expert on this, but speaking as a chemist, my guess is that
the flies are detecting sulfur compounds.  Decaying protein often develops
odoriferous (to us humans) sulfur compounds from the sulfur-containing amino
acids (eg. cysteine).  Natural gas and propane have sulfur compounds added
to give them an odor that humans can detect.  It is possible that the
bluebottle flies associate the mercaptans and sulfides that we added to the
propane with their favorite foods.
Rick