Horticultural sprays are used to control insects including aphids, caterpillars, leafhoppers, leaf miners, mealybug, mites, scale, spider mites, thrips and whiteflies on a variety of plants. They work by smothering the target insects or eggs in a coating of oil which stops the insects breathing which results in a quick kill of the insect. It is best to spray when the temperature is not to hot so early morning when it is usually calm as this will also reduce spray drift and killing beneficial insects.
There are two main types of horticultural oils mineral and vegetable both are effective at controlling pests. Two that I like to use are Eco oil and Ecofend. Eco oil is certified organic, has no withholding period and now is enhanced with a beneficial insect attractant which increases the number of ladybeetles, lacewings, hoverflies and parasitoids in the garden to help it control the pests.
Ecofend is a paraffin based oil which has better resistance to UV and rain than most horticultural oils whilst having less chance of damaging plants as it is 98% or higher unsulphonated. It has a one day withholding period
Which ever you choose please follow the instructions on the container.