At which stages is controlling insects considered moderately successful?

Controlling insects is considered moderately successful during the late instar and adult stages due to several reasons. At these stages, insects are larger and more developed, which makes them more susceptible to pesticides. Late instar larvae are often at their most vulnerable points just before pupation, making control measures more effective at this time. Furthermore, adult insects, being fully formed, are often easier to target, especially if they are exposed to environments where pesticides can be dispersed effectively.

In contrast, targeting eggs or pupa can be less effective, as they are protected by their outer layers or are in stages of development that may not respond as readily to control measures. Early nymph stages can also pose challenges as their small size and habitat can hinder effective application of controls. Thus, the combination of vulnerability and accessibility during the late instar and adult stages makes these the most effective stages for insect control.