Spraying with a rubbing alcohol solution can control insects. Ill.: Claire Tourigny

One homemade insecticide that can really do the job is 70% rubbing alcohol (isopropyl alcohol). Mix 1 part rubbing alcohol with 7 parts water and spray it on plants affected by aphids, mealybugs, scale insects, thrips, whiteflies, etc. The alcohol will melt the protective wax that covers certain insects and dry the soft body parts of others, leading to their demise. Furthermore, alcohol spray tends to draw mobile insects, notably mealybugs, out of their hiding places, making them easier to control. 

Simply spray the solution to saturation, covering all surfaces, including stems, both sides of leaves, and especially leaf axils where so many pests like to hide.

You can also add a few tablespoons of rubbing alcohol to insecticidal soaps and to other homemade insecticides to increase their effectiveness.

This treatment is most successful against nymphs and adults, but, depending on the species being treated, doesn’t always work on eggs and pupae. If so, new little pests will soon awake to try and regain control of your plant, so you’ll have to spray again every week or so until you no longer see any pests.

Do note that diluted alcohol won’t harm plants … but don’t use rubbing alcohol full strength, as it sometimes can.

What About Vodka?

Sure you could spray your plants with a solution of vodka, gin, cognac, whisky or any other hard liquor, but that will cost you a lot more than would rubbing alcohol. I suggest the keeping the good stuff for yourself!

Cotton Swab Versus Mealybugs: Don’t Waste Your Time

Cotton swabs dipped in alcohol aren’t very effective. Photo: getbusygardening.com

On other sites, you’ll see the recommendation you can control mealybugs by touching each one with a cotton swab dipped in rubbing alcohol … but I’m not going to waste your time. That simply doesn’t work. Yes, directly touching the insect with alcohol will kill it, but you’ll only be reaching the most visible pests. Others are always hiding in places where you can’t see them and soon the infestation is back again, as bad as ever. Spraying with alcohol is more likely to get to all the insects and thus to be effective.

Beware of Intoxication

Open a window when you spray alcohol solution. Photo: http://www.maidtoclean.com

Yes, I know rubbing alcohol is a pharmaceutical product widely used to in hospitals to rub down bedridden patients. It is also the main ingredient of many hand sanitizers. Even so, it is poisonous and you can become intoxicated by rubbing alcohol fumes if you use it in an enclosed area. There is no problem with using it outdoors, but always ventilate the room when you use it indoors.

Article adapted from one published on March 6, 2016.