What type of insect is primarily responsible for the damage associated with Sod Webworms?

The correct answer is larvae, as they are the life stage of the Sod Webworm that causes the most significant damage to turfgrass. When the larvae hatch from their eggs, they feed on the grass blades, creating irregular patches or small holes in the lawn. This feeding activity weakens the plants and can ultimately lead to die-back in areas where the infestation is severe.

In contrast, adults, which are the moths, do not directly cause damage to the grass; they are primarily concerned with reproduction and laying eggs. The pupae stage is a transitional phase where the larva encases itself and does not feed, and thus is not responsible for any damage. The eggs represent the initial stage of the Sod Webworm life cycle and do not contribute to turf damage until they hatch into larvae. Therefore, it is the larvae that are directly responsible for the detrimental effects on cool-season turfgrass.