Soap has been used for centuries as an all-purpose
pesticide.  Rural gardeners learned that using the leftover
dishwater to water their gardens resulted in fewer insect
pests.  It disrupts insects’ cell membranes, and kills pests by
dehydration. The key is not to use too much soap, or you’ll
also kill the vegetation near the pests. If you follow the
proportions of soap to water in the Soap Spray recipe,
below, the vegetation should be fine.

Note: Buy a liquid
soap and not a detergent.   There is a
difference.  Health food stores and Target have liquid soaps,
such as Dr. Bronner’s Pure-Castile Soaps.  Use the
unscented if you can find it.  Ivory liquid soap will work too.

Mixing Insecticidal Soap Spray:  1 to 2 tablespoons liquid
soap in 1 quart water.  One tablespoon is 14.8 ml.  One quart
is 946 ml.  Accordingly, 1 tablespoon in a quart of water will
give you a 1.5% solution.  2 tablespoons will give you a 3.0%
solution.

Make sure you spray the plant thoroughly including both the
tops and the bottoms of the leaves.  Once sprayed on, it
takes about 10 to 15 minutes to be certain the critters are
dead.  This solution kills on contact but will not prevent a
reinfestation.  If more critters come, the plants will have to
be sprayed again.  I have found that regular treatments will
begin to reduce the level of any subsequent reinfestations
though.

I recommend rinsing the plants off with clear water after the
soap spray has been on for about 15 minutes.
Insecticidal Soap Spray
(According to Big Mike)
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