How do soil moisture and rainfall affect white grub populations?

Soil moisture and rainfall play a crucial role in the life cycle and population dynamics of white grubs. When soil moisture levels are normal or above normal, it creates an environment that is conducive to the survival and development of white grub larvae. Adequate moisture supports healthy grass growth, which is vital since the larvae primarily feed on grass roots. Additionally, sufficient rainfall allows the eggs laid by adult beetles to hatch successfully, leading to an increase in the population.

In contrast, extremely low moisture levels or drought conditions can adversely affect white grub populations. Under such stress, the survival rates of the larvae may decline, as the grass they feed on may be weakened or die off, reducing their food supply. Therefore, when conditions are favorable, as indicated by normal or increased moisture levels, white grub populations are more likely to thrive, leading to higher numbers in those environments.