Which of the following are symptoms of a leaf beetle infestation on elm trees?

The presence of yellow and black striped larvae visible chewing on leaves is a definitive symptom of a leaf beetle infestation on elm trees. Leaf beetles, particularly in their larval stage, are known to have strikingly colored bodies that can be yellow and black, which is characteristic of certain species. These larvae actively feed on the leaves, leading to considerable damage, including notches and holes in the foliage. Observing these larvae directly is a clear indication of an ongoing infestation and can help in diagnosing the specific pest affecting the tree.

Other symptoms such as brown and curled leaves could be associated with various stress factors or different types of pests, and while white sticky residue on leaves may indicate the presence of sap-sucking insects, it is not a typical symptom of a leaf beetle infestation. Sparse flowering could suggest a health issue with the tree itself but does not directly correlate with leaf beetle activity. Identifying the right signs is crucial for effective pest management and treatment.