Which insects can be controlled by applications of a recommended miticide?

Applications of a recommended miticide are specifically designed to target mites, particularly spider mites, which are a common pest in horticulture. Miticides work by disrupting the life cycle or physiology of these arachnids, making them effective against spider mites while being relatively harmless to other beneficial insects and organisms. This specificity is crucial in pest management strategies, as it allows farmers and gardeners to control pest populations without harming the broader ecosystem.

The other options, such as fleas, beetles, and ants, are not affected by miticides, as these insects belong to different taxonomic classes. Fleas are insects that require insecticides rather than miticides for control, and similarly, beetles and ants are also not susceptible to treatments aimed at mites. Therefore, spider mites stand out as the correct answer, as they are the targeted pests that miticides are meant to control in horticultural practices.