What treatment for ants requires a follow-up?

The treatment option that requires a follow-up is spray applications. When using sprays for ant control, follow-up treatments are often necessary to ensure that any residual insecticide remains effective, especially given that ant populations can be very resilient and may include hidden nests or trails not initially treated. Sprays may kill exposed ants on contact, but they can leave behind a residual effect that requires monitoring and potential reapplication.

In contrast, granular bait options usually remain effective over a longer period as they attract ants to consume the bait and carry it back to their colony. Diatomaceous earth, being a physical pesticide that desiccates insects, does not typically require immediate follow-up, and its effectiveness can last until it is disturbed or washed away. Dust applications, while potentially lasting longer, also do not commonly demand follow-ups like sprays do, unless there's an evident resurgence of ant activity.

Therefore, the need for follow-up is most pertinent with spray treatments due to their immediate but often temporary efficacy, requiring ongoing observation and additional applications to maintain control over the ant population.