Fly spray is a chemical

insecticide Insecticides are pesticides used to kill insects. They include ovicides and larvicides used against insect eggs and larvae, respectively. The major use of insecticides is in agriculture, but they are also used in home and garden settings, i ...

that comes in an aerosol can that is sprayed into the air to kill

flies Flies are insects of the Order (biology), order Diptera, the name being derived from the Ancient Greek, Greek δι- ''di-'' "two", and πτερόν ''pteron'' "wing". Insects of this order use only a single pair of wings to fly, the hindwin ...

. Fly sprays will kill various insects such as house flies and

wasps A wasp is any insect of the narrow-waisted suborder Apocrita of the order Hymenoptera which is neither a bee nor an ant; this excludes the broad-waisted sawflies (Symphyta), which look somewhat like wasps, but are in a separate suborder. Th ...

Principles

Fly spray contains chemicals (including many

organophosphate In organic chemistry, organophosphates (also known as phosphate esters, or OPEs) are a class of organophosphorus compounds with the general structure , a central phosphate molecule with alkyl or aromatic substituents. They can be considered ...

compounds) that bind to and permanently block the action of an

enzyme An enzyme () is a protein that acts as a biological catalyst by accelerating chemical reactions. The molecules upon which enzymes may act are called substrate (chemistry), substrates, and the enzyme converts the substrates into different mol ...

called

acetylcholinesterase Acetylcholinesterase (HUGO Gene Nomenclature Committee, HGNC symbol ACHE; EC 3.1.1.7; systematic name acetylcholine acetylhydrolase), also known as AChE, AChase or acetylhydrolase, is the primary cholinesterase in the body. It is an enzyme th ...

. Acetyl choline (ACh) is the nerve transmitter substance released by motor neurones (at a site called the

neuromuscular junction A neuromuscular junction (or myoneural junction) is a chemical synapse between a motor neuron and a muscle fiber. It allows the motor neuron to transmit a signal to the muscle fiber, causing muscle contraction. Muscles require innervation to ...

) to stimulate

muscle contraction Muscle contraction is the activation of Tension (physics), tension-generating sites within muscle cells. In physiology, muscle contraction does not necessarily mean muscle shortening because muscle tension can be produced without changes in musc ...

. The muscles relax (stop contracting) when the ACh is removed from the

(NMJ) by the action of acetylcholinesterase. By inhibiting the

cholinesterase The enzyme cholinesterase (EC 3.1.1.8, choline esterase; systematic name acylcholine acylhydrolase) catalyses the hydrolysis of choline-based esters: : an acylcholine + H2O = choline + a carboxylate Several of these serve as neurotransmitte ...

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 Asphyxia or asphyxiation is a condition of deficient supply of oxygen to the body which arises from abnormal breathing. Asphyxia causes generalized hypoxia, which affects all the tissues and organs, some more rapidly than others. There are ...

. The Fly spray is shown to be effective against black flies. The U.S. Environmental Protection Agency released a study detailing the effectiveness of black fly spray.

Safety

Like many insecticides, fly spray can be toxic to a host of other organisms including birds, fish, beneficial insects, and non-target plants. In the United States, fly sprays often contain the powerful insect toxin

dichlorvos Dichlorvos (2,2-dichlorovinyl dimethyl phosphate, commonly abbreviated as an DDVP) is an organophosphate widely used as an insecticide to control household pests, in public health, and protecting stored products from insects. The compound has be ...

which is often targeted by

environmental group The environmental movement (sometimes referred to as the ecology movement) is a social movement that aims to protect the natural world from harmful environmental practices in order to create sustainable living. In its recognition of humanity a ...

s as a

carcinogen A carcinogen () is any agent that promotes the development of cancer. Carcinogens can include synthetic chemicals, naturally occurring substances, physical agents such as ionizing and non-ionizing radiation, and biologic agents such as viruse ...

ic compound. While the small quantities found in fly spray may be negligible, the insect toxin can contaminate soil, water, turf, and other vegetation if disposed improperly.

References

Insecticides Aerosol sprays {{insect-stub