X-Message-Number: 7698
Date: 18 Feb 97 01:23:07 EST
From: Mike Darwin <>
Subject: Identifying Flies

Doug Skrecky writes about his problems with identifying the fruit flies in his

lifespan experiments.  This problem is easily solved by the expedient of marking

the individual flies in each group.  Fruit flies may be easily anesthetized with
ether and then handled with a camel's hair brush.  Watch glasses make an
excellent surface on which to work with the flies as they tend to roll towards
the center.  Individual flies may be marked with a daub of nontoxic paint or
have a wing colored with a "Sharpie" indelible marker.  If breeding occurs you
can tell the first generation from the second one quite easily.

Fruit flies are are very difficult to kill with ether and even relatively impure
Humco brand "starting ether" such as is used to start automobiles in the cold
will work quite well.  The major caveats with ether are to:

a) realize it is incredibly flammable and explosive.
b) understand that it forms unstable explosive peroxides with water and that
storage of opened cans of ether for long periods (months) is very dangerous as
they may explode when the can is simply picked up or bumped.
c) never put ether in a refrigerator (it will quite likely blow up unless it is
an explosion proof  model).

d) ether vapor is heavier than air and it will fall to the floor and concentrate
there where a spark from static electricity can set it off.

Small amounts of ether used for anesthetizing fruit flies and handled away from
flame are safe.

Also, Doug, hopefully you have a control group!!!!!  You can't rely on the

literature numbers for the lifespans of your flies raised under your conditions.

Finally, I am very glad to see Doug doing some _experiments_.  These will
probably change his outlook on the world a lot and will likely improve his
appreciation for the tremendous amount of efort even the smallest practical
advance in science requires.

Good luck.

Mike Darwin

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