I can get a tin of spray and direct it at a cloud of fruit flies and have them spiral downwards until they are little writhing smudges on the ground. Or, if I hit a cockroach it squirms around doing spastic conniptions and expires a few minutes later.
OTOH, there are some combinations of bug spray and bug that take a while to work. There are times when I think that hairspray might be better at bringing down a house-fly. At least the little buggers will stop irritating me if their wings are stuck together. And I don’t care if it takes them a while to die.
I am left to wonder, what is the mechanism by which insecticides do their business? Am I right in guessing that it is some kind of direct attack on the nervous system and that their neurotransmitters no longer function? If that is the case, (apart from the fact that my skin is not that porous), why is it that bug spray has so little effect on me. Is it a case of my nervous system being so different that I am not subject to the same neurotoxins?
I fear that in my rambling speculation I have answered my own question. But I may be waaay off. In any case I would love to know specifics. Fight my ignorance.