Final answer:
Large white grubs are more likely visible in the late summer to autumn searching for hosts and in early spring when they emerge from hibernation.
Step-by-step explanation:
Large white grubs can most likely be found near the soil surface during the warmer parts of the year when conditions are favorable for their survival and development. These grubs are typically more active and visible in the late summer to autumn period when they are in search of a host and during early spring when they emerge from hibernation. The larvae deplete their food supply by late May to early June, which prompts adults to migrate and seek pollen to build up fat reserves for overwintering.