Illinois Field Crop Applicators Practice Test

What is a common characteristic of leaf aphids?

1. Large size and brown color

2. Sucking sap from stems and leaves

3. Feeding on roots underground

4. Cocoon-like appearance during larval stage

The correct answer is: Sucking sap from stems and leaves

Leaf aphids are characterized by their behavior of sucking sap from the stems and leaves of plants. This feeding method allows them to extract essential nutrients, which can lead to various plant health issues, including stunted growth, curling leaves, and the potential spread of plant diseases due to their role as vectors for viruses. This distinct feeding method sets leaf aphids apart from many other insects. They possess specialized mouthparts known as stylets that enable them to penetrate plant tissues and access the phloem, where they obtain the sap. Their feeding not only affects the plant's vitality but can also induce stress responses that may attract predators or parasites. In contrast, other choices refer to characteristics that do not align with the behavior and biology of leaf aphids. For instance, leaf aphids are typically small and can vary in color but are generally not described as large and brown. They also do not feed on roots, as they primarily target above-ground parts of the plant, and they do not develop in a cocoon-like manner during any of their life stages. Understanding this behavior is crucial for effective pest management strategies in agricultural practices.