What type of pesticide would be ineffective against creatures like earthworms?

In the context of pesticide application, insecticides are primarily formulated to target insects, making them ineffective against earthworms. Earthworms belong to a different taxonomic group (annelids) and do not share the biological targets that insecticides are designed to disrupt, such as specific enzyme systems or nerve functions unique to insects. This specialized targeting ensures that insecticides do not harm earthworms, which play a crucial role in soil health and structure.

Rodenticides are aimed at controlling rodent populations and herbicides are intended to eliminate unwanted plants or weeds. Growth regulators, on the other hand, influence the growth patterns of plants and are not relevant to the control of earthworms either. Therefore, none of these alternatives would target earthworms effectively. In summary, insecticides are designed for insects, making them unsuccessful against earthworms, highlighting their role's uniqueness in the ecosystem.