What is the primary purpose of a larvicide?

The primary purpose of a larvicide is to kill insect larvae. Larvicides are specifically formulated to target the early developmental stages of insects, which can include various pests that have aquatic or terrestrial larval stages. By focusing on larvae, these products effectively disrupt the pest life cycle, preventing them from maturing into adults that can reproduce and cause further infestations.

Using larvicides helps in managing pest populations more efficiently, as it targets a vulnerable stage in the insect's life cycle, reducing the number of adults that could emerge and contribute to ongoing pest problems. This method of pest control is particularly important in managing mosquitoes, for instance, where targeting the larval stage can significantly reduce the overall population and the associated risks, such as disease transmission.

The other options described, such as killing adult insects, preventing eggs from hatching, or repelling insects, pertain to different types of pesticide strategies and formulations, but they do not directly align with the fundamental role of larvicides specifically designed for controlling larvae.