Which of the following could be considered a type of contact pesticide?

Contact pesticides are designed to affect pests upon direct contact rather than through ingestion or any other means. One of the primary characteristics of contact pesticides is that they need to be able to adhere to the surface where pests are present to directly impact them.

Choosing dust as the correct answer is appropriate because dust formulations are typically designed for direct application to surfaces where pests might crawl or rest. When pests come into contact with the dust, the active ingredients are transferred to them, leading to their demise. Dusts are often used in environments such as cracks and crevices where pests congregate, making them an effective choice for immediate contact with targeted pests.

In contrast, growth regulators influence the development and reproduction of pests rather than killing them on contact, while fumigants are gaseous pesticides that penetrate areas to exterminate pests without immediate contact. Liquid residuals can also be effective, but they require some time to dry and do not act solely through contact until the pesticide has adhered to the surfaces. Thus, dust is the clearest example of a contact pesticide among the provided options.