Which alfalfa pest is often overlooked but causes considerable damage?

• A. Grasshopper
• B. Potato leafhopper
• C. Pea aphid
• D. Alfalfa weevil

Answer: (B)

Small sap-sucking insects like the potato leafhopper can cause substantial yield loss in alfalfa, even when their numbers don’t look high. They feed on the soft, growing parts of the plant, injecting toxins as they suck sap. This leads to hopperburn: the new leaves curl, yellow or redden, and growth slows. The damage is especially harmful in young stands or regrowth during warm weather, and it can reduce stand persistence after harvest.

What makes this pest tricky is its size and the subtlety of symptoms early on. The insects are tiny and can move quickly, so scouting can miss them. The resulting plant stress can resemble drought effects or nutrient deficiency, so the damage isn’t always recognized right away. Because of this, potato leafhopper tends to be overlooked even though it can cause substantial losses.

Other pests listed tend to show more obvious or different kinds of damage—grasshoppers leave visible chewing holes, pea aphids often form noticeable colonies and produce honeydew, and alfalfa weevils produce clearer skeletonizing and can be detected by seeing the insects or their damage patterns. That contrast helps explain why the leafhopper is commonly overlooked yet remains a major threat to alfalfa yields.