Ornamental and Turf Pesticide Applicators Practice Exam

What do the grubs of Japanese beetles feed on?

1. Organic matter and grass blades

2. Roots and organic matter at the soil-thatch junction

3. Surface turf and foliage

4. None of the above

The correct answer is: Roots and organic matter at the soil-thatch junction

The grubs of Japanese beetles primarily feed on roots and organic matter at the soil-thatch junction. This feeding behavior is particularly damaging because it affects the root systems of grass and other plants, leading to poor health and potential death of the affected turf. The roots are essential for water and nutrient absorption, and when grubs consume them, it compromises the overall stability and growth of the plant. Additionally, by feeding at the soil-thatch interface, they can disrupt the soil structure and the organic materials that contribute to the ecosystem of the lawn or garden, further contributing to plant stress. The other choices do not accurately represent the grub's dietary habits. Option A suggests that grubs feed on grass blades and organic matter, which is not correct since they do not primarily consume the visible parts of the grass but rather the roots. Option C mentions surface turf and foliage, which is also inaccurate for grub feeding behavior. Lastly, option D is not applicable, as there is indeed a correct answer within the given choices that reflects the grubs' true feeding patterns.