What is one symptom of feeding by billbugs?

Billbugs are known for their feeding habits, which primarily target the stems and crowns of grasses. When they feed, they create damage that affects the structural integrity of the grass plants. As a result, one prominent symptom of their feeding activity is that the stems break easily when pulled upon. This is due to the weakening of the tissue where the billbugs have fed, which compromises the plant's ability to withstand physical stress.

Other symptoms such as yellowing leaves might be associated with various types of pest damage or environmental stress, but they do not specifically indicate billbug feeding. Similarly, while branches dying off and roots rotting quickly might result from other issues within the plant health spectrum, they are not characteristic symptoms of billbug infestations. The specific action of breaking easily when pulled is a clear indicator of the damage billbugs can cause to the host plant.