|MadSci Network: Agricultural Sciences|
If you have something that repels or kills insects, will it repel or damage birds?
Walnut oil is a drying oil (heavy in linoleic and linoleic acid esters). You would get there more easily with traditional drying oils such as linseed or tung. I don't expect any special repellent effect.
Cedarwood contains cedrene and cedrol which are known insect repellents. Add a cedarwood panel to the interior. http://juniper.orst.edu/adams.htm
Cashew nut shell liquid (oil of cashew nut shell, Anacardium occidentale) contains cardol (irritant) and anacardic acids. They are quite nasty - contact dermatitis. It air cures in thin layers and retains its nastiness. Kiurushi sap - Japanese lacquer, Toxicodendron verniciflua - is rich with branched chain alkylated catechols (1,2-dihydroxybenzenes) and resorcinols (1,3-dihydroxybenzenes) just like poison ivy. It also contains a trace of the enzyme laccase that air oxidizes it to the famous black Japanese lacquer coating (but *only* in thin layers!) Nastiness is retained. Mango skin oils are also nasty, and for the same reason.
Why not put a few bay leaves in each of the the finished bird houses and call it a day? Bay leaves are rich in sesquiterpene lactones which have distinct insect repellent effects.
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