Which type of pesticide must come into contact with the pest to be effective?

The effectiveness of a contact pesticide relies on its ability to directly touch the pest to exert its effects. This type of pesticide needs to come into direct contact with the target organism, such as insects or weeds, to disrupt their physiological processes. Unlike systemic pesticides, which are absorbed and then transported throughout the plant to affect pests that feed on it, contact pesticides must be sprayed or applied directly onto the pests for successful control.

Residual pesticides, on the other hand, may remain active on a surface for a period, but still require direct contact with the pest to be effective. Selective pesticides, while they target specific pests without affecting others, can be either systemic or contact types, so they do not inherently require contact for the same effect as contact pesticides do. Overall, contact pesticides are crucial for targeting visible pests and providing immediate results in pest management strategies.