|MadSci Network: Zoology|
Most contemporary household bug killers are based upon pyrethroids - synthetic analogs of the insecticidal principle of African pyrethrum daisies (Chrysanthemum coccineum or Tanacetum coccineum).
Pyrethroids act by lethally altering the permeability of excited nerves.
Their rapid metabolism in mammals and very fast knock-down in insects make
them popular. Carbamate and phosphate insecticides inactivate the enzyme
acetylcholinesterase at the nerve-muscle junction. They both have long
term harmful effects after exposure.
Pyrethroids are not especially lethal to roaches. They are more like
fast-acting aesthetics. If you want to kill roaches, you need something
Dead things often end up on their backs because that is the equilibrium
position with their center of gravity lowest to the ground. Dead fish
float upside down because that places their center of gravity nearest the
surface. Either way, the energy of the system is minimized. SUVs easily
tip over for the same reason - too high a center of gravity.
http://www.mazepath.com/uncleal/eotvos.htm (Do something naughty to physics)
Try the links in the MadSci Library for more information on Zoology.