Illinois Field Crop Applicators Practice Test

Which pest causes damage characterized by skeletal leaves and fields appearing frosted?

1. Spider mites

2. Bean leaf beetles

3. Alfalfa weevil

4. Soybean aphids

The correct answer is: Alfalfa weevil

The pest that causes damage characterized by skeletal leaves and fields appearing frosted is the alfalfa weevil. This pest primarily affects alfalfa crops and is known for its distinctive feeding behavior. The larvae of the alfalfa weevil feed on the leaf tissue, creating a skeletonized appearance because they consume the soft leaf material while leaving the tougher veins intact. This results in a frosted or damaged look to the leaves, giving a clear visual indication of the pest's activity. In contrast, the other pests listed have different feeding habits and damage profiles. Spider mites cause stippling and discoloration, rather than a skeletal appearance. Bean leaf beetles typically create more large holes in leaves and could cause defoliation, but their feeding does not lead to the frosted appearance typical of alfalfa weevil damage. Soybean aphids suck sap from plants, leading to yellowing and distortion rather than the skeletal leaves associated with the alfalfa weevil. Understanding these specific characteristics helps in accurately identifying pest damage in fields.