Research from India highlights this amazing plant, usually used as a carminative, immune stimulant, antifungal and "toothache plant". Members of the Spilanthes genus, but in particular S. acmella (my favorite garden variety) seem to kill the larvae of mosquitoes at concentrations of 9ppm (9/1000ths of 1%), which seems really low (about 3 drops of their extract for a full 5-gallon bucket). The researchers used hexane to extract pungent alkylamides from the flower heads, then removed the hexane to leave what was probably a very concentrated (up to 20:1) fraction. Still, a more reasonable 1:5 weigh-to-volume ratio would still mean that 10ml to 15ml of tincture (of high alcohol percentage!) could provide the adequate concentration to kill all mosquito larvae in a 5-gallon bucket.This research is geared towards containing the spread of malaria and filaria, carried by mosquitos which then infect humans. Considering the increase in the incidence of mosquito-borne disease here in the US (West Nile, e.g.), and the toxic chemicals used to control them in places like New York City, we might all want to consider some Spilanthes extract instead...