Cecil’s column www.straightdope.com/classics/a1_023.html brought to mind a remedy my mother once told me for that very problem. Apparently, if you mix about 5 drops of “Ivory” dish-soap (she said no other brand works) in every litre of water and water your plants as normal, the bugs will be gone in less than a week. Has anyone else ever heard of this?
Your mother grew marijuana?!? Boy do I feel old all of a sudden.
I think your mom must have meant “put the soapy water in a spray bottle and spray the plants”, which is a classic organic pest-control solution. However, it doesn’t have to be Ivory Soap brand–any brand of dish soap (which is really detergent) will do.
http://cals.uvm.edu/ctr/el/el38.htm
Spraying the plants with soapy water works, both because some bugs have a waxy outer coating that the detergent destroys, and because of simply physically washing the bugs off the plants.
Ivory Dish Soap, BTW, is no longer “soap”.
Hi Guys -
This is my first post on this forum, the reason bugs die when you spray them with detergent is that the detergent forms a film over the insect. Now as insects breathe through small holes all over their body (called spiricles) - they suffocate.
Much like when you use white oil - the oil blocks their breathing holes and they die.
Any olde detergent will do the job 
HTH -
YeW
What’s “white oil”?
I guess that’s oil that is not black.
All kidding aside, the soap spray is a mechanical fix to the problem, and is the most effective. Unfortunately, this also means that attaining such success requires a dramatic input of attention and time, soaping them up like twice per day.
Although thirty years too late (according to the date of the article) it sounds like Spider Mites, the dreaded scourge of the home marijuana-cultivation masses. Pyrethrum is the safest peticide and is explained to break down to “organic” elements. Well, consider that most biological poisons are “organic” as well, and I wouldn’t smoke anything that was recently sprayed with something designed to kill other thins. The ideal solution, although also a pain, is to introduce a natural predator. Lady bugs are entirely ineffective against spider mites because they reproduce too quickly and rapidly colonize and recolonize. As such, they have specific mite-predators, available at your local garden supply house (major ones, and not hokey operations like Home Depot). Infestations of these buggers are quite rampant for normal houseplants. My dracaena was attacked mercilessly, and I had to give it up because of likely spread to my orchids.
Just two cents of mine.
Hi All -
White Oil = Petroleum Oil.
You can buy in an aerosol to kill scale insects, aphids, mealy bug etc.
HTH -
YeW
BTW, the column can also be found on pages 23-24 of Cecil Adams’ book «The Straight Dope (1984; reissued 1986, 1998)».