I’m a mosquito magnet and lemon eucalyptus works wonders, as long as I use it. Last night, I ran outside for only seven seconds, but my legs were exposed and I got 10 miserable bites. There is nothing a mosquito wants more than my blood. It got me thinking, has anyone tried using lemon eucalyptus on fruit trees? Or berries? I don’t know it’s toxicity for pollinators, or how long it would last. And, it certainly would need to be pretty dilute. (My frantic experiment on pumpkins last year showed it will eat right through the skin…) Just thought I would put out the question.
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It would probably alter the flavor of what you spray with it, and it might not deter the pests you want it to deter, but on the other hand it’s probably not dangerous to pollinators, no.
A few things are useful to know. The first being that “oil of lemon eucalyptus” is in fact, not the essential oil of a eucalyptus, or an essential oil at all. It’s a chemical called p-Menthane-3,8-diol. It’s produced by treating and refining the oil extracted from Corymbia citriodora, which is a close relative of eucalyptus but not generally included in the genus Eucalyptus these days. That oil is mostly citronellal, not to be confused with citronellol or citronella oil which are related but not identical things. Citronellal will normally convert to p-Menthane-3,8-diol over time, but the industrial production of p-Menthane-3,8-diol uses special treatments to catalyze and speed the conversion from citronellal. Also, lemongrass oil is similarly mostly citronellal, and so a lot of “lemon eucalyptus oil” is actually synthesized from lemongrass. Actual eucalyptus oils are usually produced from Eucalyptus globulus and mostly contain cineole which is a pretty different chemical and is moderately toxic. But there are hundreds of eucalyptus species and their essentials oils are extremely diverse, ranging from lemony and piney to minty, peppermint, and even fruity and strawberry like depending on the species. Generic “eucalyptus oil” is mostly cineole is is probably not food safe except in very low concentrations like is found in some Australian red wines. A fair number of people, mostly children, have been hospitalized after consuming or inhaling cineole aka eucalyptus essential oil.
p-Menthane-3,8-diol is itself quite similar to menthol. It’s not known to be dangerous to bees at realistic concentrations. Being similar to menthol, it probably doesn’t stick around for very long when exposed to air, and it has low solubility in water so it’s probably not going to be absorbed well by most plant tissue. Waxy or oily tissues or glands might absorb it some, in which case it’d probably be similar to when applied to human skin–lasting for a few hours.
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Fascinating information, thank you.