What is it in wasp spray that kills them and why isn't harmful to us?

I just nailed this big wasp that was coming right at me with a good few blasts of wasp spray, thereby earning me the undying love from the damsel in distress I share an office with. (if ever there was a moment to do the "Hail to the king, baby" line from the Evil Dead, it was then. What a wasted opportunity.)

But as I watched Mr Wasp quietly slip away, with a few extra blasts as it lay there to make it as quick as I could (I called them 鈥渃ontrol shots鈥? and I could tell the damsel dug it.) I had a thought. Reassured that he didn鈥檛 have the faculties to worry about who was looking after his babies or lamenting his wasted life as a hive drone or wishing he could have finished his novel, I wondered, what exactly what was the spray doing to him? And more importantly, why wasn鈥檛 it doing it to me? Our Damsel said she hopes it was a genetically modified nerve agent, but I feel that's a bit extreme, as well as quite unlikely this side of the iron curtain.

Can someone enlighten us?

They don't let me bring boomsticks to work anymore, there was an incident.

Okay, how about a little perspective here.

Hi, I'm the damsel of the piece and have not been portrayed too well here. I didn't say I hoped it was a nerve agent, I just gave this as a suggested answer to the question.

I know it鈥檚 not nice to kill things but I have a wasp phobia and hate them in the office with me. Admittedly, while this whole sorry episode was playing out I was hiding in the corridor, but I was not the one screaming like a girl as I danced around with the was killer in my hand. And I did not end up crying over my wasp killer tainted soup.

Oh, and so that no-one can say I didn't try to actually answer the question the active ingredient is Tetramethrin which attacks the insects nervous system.

Hairspray and starch. Makes their wings stick together.

it is but not in those minute amounts

The damsel wasn't too far from the truth. Domestic insecticide sprays usually contain chemicals called Acetylcholinesterase inhibitors. These chemicals interfere with the nervous systems of insects, in effect paralysing them and causing them to suffocate. If you were to inhale enough of the spray the same would happen to you, but because the insects are so much small they only need a tiny dose.

the thing is, the spray u used is indeed harmful to us. What Famers use on their rops, pesticides, kill bugs, but is also starting to harm us too. Thats why so many food companies and the USDA have switched to producing organic food. While a few sprays wont kill us becuase we are much bigger an comples that a wasp, it can harm us if overused or inhaled.

It's poison, non-selective poison. the thing of it is in the amounts used it is fatal to bug and not fatal to humans, that's not to say it's harmless, but the amount used will not kill you.

Gimme some sugar, baby!

Anyway, I'm not sure exactly what kind of spray you used, but if its anything like RAID, it uses a neurotransmitter called Achetylcholine. ACH is a common neurotranmitter found in the body. Its main function is muscle contraction. Let's say you had your arm relaxed, laying on the table in front of you. In order to bend at the elbow, your neurons release ACH onto your the smooth muscle of your bicep, causing it to contract. The contraction of the muscle pulls your forearm, bending at the elbow. Simultaenously, the muscle on the underside of your arm is relaxing. The opposite would happen if you wanted to lay your arm back flat. The bicep would relax, and the neurons on the underside would release ACH, pulling your forearm back down. Now, imagine what it would feel like if both sets of muscle released ACH at the same time. Your arm would go rigid, because both sets of muscles would be pulling at the same time, and I guarentee you it would be painful.
What RAID does is spray ACH all over the insects, causing all of their muscles to contract at one time. That's why a lot of times the bugs go rigid or twitch, because all of their muscles are pulling at once.
Not to rain on your parade, but you gave that wasp a pretty long, painful death. While it may be motionless, its because it physically can't move. Next time just use your boomstick.
Oh, and that spray can absolutely hurt people. Its just that spraying it away from you, it doesn't hurt you in such small quantities. However, this is why they say don't crawl under the sink and start spraying, because you'll die, too. Because what's the most important muscle in a body? The heart! Imagine if your heart contracted and never relaxed. No more bloodflow.