Emulsifiable concentrate formulations are used:

Emulsifiable concentrate formulations are specifically designed for situations where short-term residual effects are desired. These formulations consist of active ingredients dissolved in a liquid, which allows for efficient application and rapid absorption by the target pests. Because they are absorbed quickly by the insects, they provide immediate knockdown, making them particularly useful in situations where swift action is needed, such as controlling mosquito populations soon after they emerge.

These formulations typically do not have the long-lasting residual characteristics associated with other product types, which is why they are favored for short-term applications. This aligns with the need in mosquito control efforts where immediate results are more critical than prolonged effects, especially in areas with rapidly changing pest populations.

The other choices suggest applications or conditions that do not align with the primary usage characteristics of emulsifiable concentrates. For instance, the notion that these formulations are used during difficult spraying conditions or primarily in specific environmental conditions does not reflect their efficient application versatility.