What type of pest can be effectively controlled using dormant oil?

Dormant oil is a horticultural oil that is particularly effective in controlling pests during their dormant stages, often applied during the late winter or early spring months when the plants are not actively growing. Scales, which are sap-sucking insects that often attach themselves to the stems and leaves of plants, are best targeted during their dormant period when they are less mobile and more vulnerable to treatments. The oil works by suffocating the insects and disrupting their life cycle.

While dormant oil can have some effect on other pests, its most efficient use is against scales because it can effectively penetrate their protective coverings, which offer them some resilience against other types of treatments. Mites, although they can also be managed with oils, do not have the same vulnerabilities as scales during dormancy. Beetles and leafhoppers typically have more active life stages during the times dormant oils are applied, making them less susceptible to this type of control method. Therefore, the use of dormant oil is specifically aimed at controlling scales, capitalizing on their dormant lifecycle for optimal effectiveness.