One tablespoon (14.79 milliliters) to one gallon (3.79 liters) is a ratio of soap to water when spraying plants for bugs. Too strong of a spray may harm non-target animals and plant surfaces. Soapy water takes the store-bought form of insecticidal soaps.
it will keep certain bugs away from all types of plants.
for aphids, buy a bag of ladybugs at Home Depot, and for larger bugs, have a sprinkler near the plant. (grasshoppers are affraid of water)
soapy water will kill most soft skin insects on out door plants snice you have not identifyed as to wether it is a hard shell beatle or not i can't tell you for sure I use liquid dawn dish soap on the plants in my garden and on my fruit trees orange'lemon'grapefruit'and peach trees and it kills 90% OF THE INSETS THAT I FIND'.
spray infected areas with soapy water
yes, it is ok to use soapy water to rid tomato plants of small insects. I put about 1 tsp of liquid dish soap to about 1 1/2 quarts of water. I spray lightly the leaves that have bugs. This is all i use on my garden to kill insects in my whole garden.
If your roses have aphids spray with an insecticide. If you are organic use soapy water or wash off with a hose.
Plants, bugs, and water
Cedar is a great wood to burn if you want to repel bugs. I wouldn't stop with wood though, there are a number of plants you can burn as well. Some plants to try are citronella, lemongrass, rosemary, and thyme.
Carnivorous water bugs feed off small invertebrates and fish by sucking out their fluids. Omnivorous water bugs feed off freshwater plants.
Water boatmen eat algae and aquatic plants.
Add a bottle of "Pool First Aid". This will break the water's surface tension and the striders can't stay afloat and will drown. This is a temporary fix because, in my experience, more always show up.
Continued use of soapy water strips the protective cuticle off of plant leaves - this can result in the leaves burning. The occasional use of soapy water to kill small insects such as aphids, scale and mealy bug is okay - as long as you don't do it too frequently. The long term effects of soapy water on the soil are not good, this causes a layer to build up on the soil and also effects osmosis in the soil - which can cause plants to deteriorate and die