Fly spray

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Fly spray

Fly spray is a chemical insecticide that comes in an aerosol can that is sprayed into the air to kill flies. Fly sprays will kill various insects such as house flies and wasps.


Fly spray contains chemicals (including many organophosphate compounds) that bind to and permanently block the action of an enzyme called acetylcholinesterase. Acetyl choline (ACh) is the nerve transmitter substance released by motor neurones (at a site called the neuromuscular junction) to stimulate muscle contraction. The muscles relax (stop contracting) when the ACh is removed from the neuromuscular junction (NMJ) by the action of acetylcholinesterase. By inhibiting the cholinesterase the insect can no longer break down ACh in the NMJ and so its muscles lock up in a state of tetany (continuous contraction) making flying and respiration impossible, and the insect then dies of asphyxiation.


Fly spray is dangerous to pets as well as fish and should be used with caution.[citation needed]

In the United States, fly sprays often contain the powerful insect toxin dichlorvos which is often targeted by environmental groups as a carcinogenic compound.[1]

Old fly spray

There is an urban legend circulated on the Internet recommending that wasp spray be used in the place of pepper spray.[2][3]


  1. ^ Raeburn, Paul (14 August 2006). "Slow-Acting". Scientific American.
  2. ^ Emery, David (20 January 2010). "Does Wasp Spray Work for Self-Defense".
  3. ^ Mikkelson, David (21 May 2015). "Wasp Spray for Self-Defense?". Snopes.