What condition would cause flea pupae to emerge as adults?

• A. Direct contact, increased temperature
• B. Dog barking
• C. Above 60% humidity
• D. Freezing

Answer: (A)

Flea pupae stay dormant in cocoons until they sense cues that a host is nearby, then they emerge to feed. The strongest trigger is direct contact with a warm, moving host, which provides both heat and vibration signals indicating a host is present. That combination is what prompts the pupae to break from the cocoon and become adults ready to bite. Humidity levels can influence flea survival, but emergence hinges on host cues, not environmental humidity alone. Barking doesn’t convey a detectable host signal for fleas, and freezing would keep them dormant or slow development.