Because it also kills honeybees, avoid applying the product to crops in flower. Insecticidal Soap . This liquid contains fatty acids derived from plants or animals. An effective application must hit the underside of leaves where pests often gather. Avoid applying insecticidal soap on hot, sunny days because it may burn leaves.
Insecticidal soap kills many types of insects, including some beneficial species, on contact.
Extracts of the neem, or Indian lilac tree, possess a range of insecticidal properties and also have antibacterial, antiviral and antifungal properties. Neem extracts have been shown to prevent insect feeding and oviposition, and to act as a growth regulator. Several important greenhouse pests, including the greenhouse and sweetpotato whitefly, Western flower trhips and mealybug, are included on the label of the most widely-available formulation, Margosan 0. The long residual synthetic pyrethroids are based on the chemistry of pyrethrum. Pyrethrum is a contact insecticide and must be applied directly to the insect to be effective.