True Armyworm infestations typically occur when?

• A. June and July
• B. March and April
• C. December and January
• D. September and October

Answer: (C)

True Armyworms tend to outbreak when conditions are cool and grasses are still available to feed on, which in many rangeland areas happens during the winter months. Eggs hatch and larvae feed on pastures as temperatures are mild enough for development but not so hot that plant growth speeds up and the pest activity shifts. That combination—pests active and forage still present—makes December and January the time you’re most likely to see noticeable infestations. In hot summer months, conditions aren’t as favorable for these caterpillars to build large populations, and by spring the dynamics of growth and other pests change, so winter outbreaks are the typical pattern.