Which alfalfa pest is associated with dry-year outbreaks causing mid- to late-summer damage?

• A. Alfalfa weevil
• B. Grasshopper
• C. Garden webworm
• D. Cowpea aphid

Answer: (B)

Grasshoppers are strongly tied to dry-year outbreaks in alfalfa. In hot, dry conditions, vegetation is sparse and ground cover is thin, helping grasshopper populations build up and survive. As summer progresses, nymphs and adults feed heavily on alfalfa foliage, causing defoliation that can rapidly reduce yield and forage quality. This feeding pattern and timing—mid- to late-summer damage during drought years—fits the scenario described, making grasshoppers the best choice.

The other pests typically don’t follow this drought-linked, mid- to late-summer pattern. Alfalfa weevils usually cause most damage in spring to early summer, while garden webworms and cowpea aphids tend to peak at different times or under conditions not as closely tied to dry-year outbreaks.