|MadSci Network: General Biology|
Wow! What a hard question! I found a gazillion sites listing garlic and mint as home remedies for ant problems, but almost nothing on WHY garlic, or other plants, repel ants. Here is some of the information I found, and I hope you find it helpful. Most plants produce defensive chemicals that help fend off insects and diseases. These chemicals may be insect poisons, make insects stop eating, or kill fungi. Destructive insects often locate their food by smell. Many plants, especially herbs, produce strong scents which may confuse insect pests looking for something to feed on. Garden vegetable plants such as garlic, onions, chives, and herbs such as catnip, horehound, wormwood, basil, tansy, and mints all produce scents which seem to repel insects or mask the scents which attract insects. (http://www.cce.cornell.edu/suffolk/grownet/organic/complant.htm) Garlic contains many chemical compunds including "allicin" which makes the garlic smell, and "ajoenes" which can kill fungus (maybe the ants know garlic will kill their main food source, fungi). (http://www3.mistral.co.uk/garlic/chemicals.htm) Spearmint also contains many chemicals including carvone which sometimes causes an allergic reaction. Also present are other chemicals like Phellandrine, Limonene, and Dihydrocarveol acetate, acetic, butyric and caproic or caprylic acids. These strong smelling compounds may be disgusting to ants, and spearmint is known to have kill insects. (http://www.cis.um.edu.mt/~phcy/symp/lilibarb.htm) I don't know about bayleaves, but presumably they also repel moths. More home remedies for ants: http://chppm-www.apgea.army.mil/ento/mythconc.htm#ants See also : "Plants that repel" http://www.gifted-gardener.com/giftedgardener/planthatrep.html
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