# How do Insecticides work?

**URL:** <https://boards.straightdope.com/t/how-do-insecticides-work/221478>\
**Category:** Factual Questions\
**Created:** [December 28, 2003, 11:59pm UTC](https://boards.straightdope.com/t/how-do-insecticides-work/221478 "2003-12-28T23:59:52Z")\
**Posts on this page:** 6\
**Page:** 1

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**Author:** ![Honesty](https://avatars.discourse-cdn.com/v4/letter/h/f04885/32.png) [@Honesty](https://boards.straightdope.com/u/Honesty)\
**Post date:** [December 28, 2003, 11:59pm UTC](https://boards.straightdope.com/t/how-do-insecticides-work/221478/1 "2003-12-28T23:59:52Z")

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When I spray a cockroach with some Raid, what is happening to it biochemically? I know that many insects turn over and kick their legs in the air. Why do they do so? Is it interferring with some type of physiological pathway?

Also, why aren’t the same things to observed humans or other animals?

Thanks!

- Honesty

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**Author:** ![Squink](https://avatars.discourse-cdn.com/v4/letter/s/b5e925/32.png) [@Squink](https://boards.straightdope.com/u/Squink)\
**Post date:** [December 29, 2003, 12:41am UTC](https://boards.straightdope.com/t/how-do-insecticides-work/221478/2 "2003-12-29T00:41:38Z")

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[Raid contains](http://216.239.41.104/search?q=cache:MXYwNK6PUt4J:www.e-musa.com/MSDS/000159.pdf+Raid+ingredients&hl=en&ie=UTF-8) the artificial pyrethrin Tetramethrin, and a pyrethroid potentiator piperonyl butoxide.  
The pyrethrins kill by interfering with the operation of sodium channels in insect neurons. [Here’s](http://www.entm.purdue.edu/Entomology/people/barry/Sodium_Channel/body_sodium_channel.html) a description of the sodium channels, and their interaction with pyrethrins. It gets technical _fast_. but there are some pretty pictures of the channel.

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**Author:** ![Khadaji](https://avatars.discourse-cdn.com/v4/letter/k/9e8a1a/32.png) [@Khadaji](https://boards.straightdope.com/u/Khadaji)\
**Post date:** [December 29, 2003, 12:43am UTC](https://boards.straightdope.com/t/how-do-insecticides-work/221478/3 "2003-12-29T00:43:16Z")

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Dunno about RAID, but here is the scoop on [Dursban](http://science.howstuffworks.com/question440.htm) which is a pesticide.

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**Author:** ![Squink](https://avatars.discourse-cdn.com/v4/letter/s/b5e925/32.png) [@Squink](https://boards.straightdope.com/u/Squink)\
**Post date:** [December 29, 2003, 12:48am UTC](https://boards.straightdope.com/t/how-do-insecticides-work/221478/4 "2003-12-29T00:48:46Z")

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As that second link mentioned, the ability of pyrethrins to bind to and inhibit sodium channels depends on the precise amino acid sequence of the channel protein. Fish share enough of that sequence with insects that they are quite sensitive to pyrethrins, but birds and mammals do not.

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**Author:** ![rjk](https://avatars.discourse-cdn.com/v4/letter/r/ed655f/32.png) [@rjk](https://boards.straightdope.com/u/rjk)\
**Post date:** [December 29, 2003, 7:30am UTC](https://boards.straightdope.com/t/how-do-insecticides-work/221478/5 "2003-12-29T07:30:57Z")

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As **Squink** points out, pyrethrins can kill more than insects.

Insecticidal soap (or a little dish soap) kills insects by washing away the waxy coating that keeps them from drying out, and isn’t very toxic to other things.

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**Author:** ![The\_Long\_Road](https://avatars.discourse-cdn.com/v4/letter/t/b5a626/32.png) [@The\_Long\_Road](https://boards.straightdope.com/u/The_Long_Road)\
**Post date:** [December 29, 2003, 11:44am UTC](https://boards.straightdope.com/t/how-do-insecticides-work/221478/6 "2003-12-29T11:44:23Z")

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Does anyone know why when I spray a roach with Raid or something similar the bastards come flying after me? Is it their way of saying,“Haha bitch, I might die but I am going to make you run!!”?