What is a key step in making an effective residual bin spray?

Using a residual bin spray effectively is not just about treating the interior of the storage area, but also about ensuring that the pests do not have an entry point. Spraying around outside areas, such as doorways, is crucial in creating a barrier that helps prevent pests from entering the bin. This approach addresses potential sources of infestation before they can compromise the stored materials.

The effectiveness of a residual spray lies in its ability to maintain a long-lasting protective presence, and treating areas outside the bin can significantly enhance this protection. It helps to reduce the likelihood of reinfestation, which is especially important in managing pests that might be seeking entry from outside.

The other answer choices fail to address the comprehensive pest control strategy needed. Focusing only on the surface or the inside of the bin might leave vulnerable points unprotected, and using weak pesticide mixtures does not provide adequate control over pests that could threaten stored goods. Therefore, creating a robust barrier through targeted treatment around the outside areas is a vital part of an effective residual bin spray process.