Certified Professional Horticulturist (CPH) Practice Exam

Which of these insects have the potential to cause lawn damage and should be controlled immediately?

1. Aphids

2. Lace wings

3. Leaf miners

4. Japanese beetles

The correct answer is: Japanese beetles

Japanese beetles pose a significant threat to lawns and various types of vegetation due to their destructive feeding habits. These insects are known to consume a wide range of plants, leading to visible damage such as skeletonized leaves and overall decline in plant health. Their larvae, commonly referred to as grubs, can also be damaging as they feed on grassroots, which can result in browning, patchy areas in lawns and can ultimately lead to significant turf loss if left uncontrolled. Additionally, the presence of Japanese beetles often indicates the potential for rapid population growth, making immediate control measures crucial to prevent extensive damage. Effective management strategies, including the application of appropriate insecticides or biological controls, can help mitigate their impact and maintain a healthy lawn. In contrast, while aphids and leaf miners can cause issues in gardens and some ornamental landscapes, their immediate threat to lawns is generally less severe compared to Japanese beetles. Lace wings are beneficial insects that help control pest populations, rather than being harmful themselves. Thus, monitoring and managing Japanese beetles becomes imperative for maintaining lawn health and preventing extensive damage.