posted by: jimster on 10.18.2006 at 08:26 pm in Vegetable Gardening Forum

"It was only after reading this thread that I remembered saving a couple of recipes last year -- recipes which would have been useful this year if I had remembered sooner.

INSECTICIDE: A U.S.D.A. formula combining oil and soap is effective in killing soft-bodied insects. Mix 1 cup peanut, safflower, corn, soybean, or sunflower oil with 1 tablespoon liquid dishwashing detergent. To make the spray, use 11/2 teaspoons of the oil-detergent mixture for each cup of water...."

This question comes up fairly frequently, so I'll try to keep this formula posted, in the event that it disappears from my clippings (as some posts already have).

I've had good luck adding 1 tsp. of sugar to the soap spray; it will kill even cucumber beetles, if they are completely saturated. It is also highly effective against squash bugs, both adults & nymphs. Soap sprays in general tend to burn foliage, so they should be targeted on the insect pests directly, not sprayed over a wide area. If large leaf surfaces are sprayed, they should be rinsed as soon as the insects have died, about 1 hour after application.

For wider infestations, it might be better to use an insecticidal soap such as Safers, which is less likely to cause severe leaf burn. Safers also qualifies as organic... dish soap, while non-toxic, may not meet that qualification.

A mixture of soapy water & rubbing alcohol in a spray bottle will kill wasps... it literally knocks them out of the air. The bottle should have a strong spray, such as the horse spray bottles sold in Farm & Fleet stores.

Flee beetles are a little tough to kill, and since they are spread out over a large area (as opposed to grouped together), they need a spray that is broad-coverage. That rules out dish soap. Insecticidal soap alone won't kill them, but mixed with rotenone, it might kill enough to prevent severe damage.

Personally, I don't like broad-coverage sprays of any type, and seldom use them. They kill not only the pest targeted, but any natural insect predators that might be present. The predator population is usually slower to recover, while the pest multiplies quickly - so over time, such spraying can actually make the problem worse. I usually just tolerate insect damage, unless it becomes severe.