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I currently have indoor potted basil and peppermint plants. Unfortunately, aphids have taken up residence in the peppermint and are spreading to the basil.

Several internet sources say that rubbing (isopropyl) alcohol can be used to kill aphids, by using a cotton-swap doused in alcohol to rub them away.

My worry is that, I plan on eating some of the leaves of the basil and peppermint plants, either chopped up in dishes, or used to make tea.

Will the alcohol be absorbed by the plant, and if so, will it make them poisonous to eat? Or is it safe to use rubbing alcohol for pest control on edible plants?

An alternate idea I had was to use artificial vanilla extract, which contains food alcohol (ethanol), but I don't know if this is a good idea.

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Isopropyl alcohol acts as a desiccant and melts the wax that is some insects bodies.

It also evaporates so very little remains. It is not absorbed by the plant and washing with water after you harvest is recommended anyway.

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    And at cooking temperatures , no isopropyl will remain.
    – blacksmith37
    Sep 29, 2021 at 14:38
  • If you live in a place where Everclear (190 proof ethanol) is available, that could be used, though it's probably more expensive.
    – Pointy
    Oct 1, 2021 at 21:44
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If you're going around rubbing all the leaves anyway, you may as well just squeeze a little harder to squish all the aphids to death. More will come regardless of whether you use rubbing alcohol or squish them.

The isopropyl will evaporate but the additives won't. In the US, by law, all rubbing alcohols must have additives added to make it poisonous. Even ethyl alcohol will have bitterants and poison added to avoid the alcohol tax. They also often have stabilizers added so that they don't evaporate away too quickly after you open the container.

The residue can easily be washed away, but some of it could drip into your soil just from dew buildup in the morning. Why bother spending extra money when you can add a little bit more pressure on your fingers and kill them right there?

Aphids are quite weak, even a hard jet of water will push them off the leaves. The flying ones that start new colonies are the ones to watch out for...and there's not much to do to stop them completely.

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