Which statement about flea control with IGRs is true?

• A. They Primarily Affect the Egg Stage
• B. They Quickly Kill Adult Fleas on Contact
• C. They Repel Fleas From Treated Areas
• D. They Provide Immediate Relief From Flea Bites

Answer: (A)

IGRs in flea control work by disrupting the development of fleas after they hatch, rather than killing adults on contact. They mimic juvenile hormone, so larvae and developing stages can’t mature into biting adults. Because their main effect is on immature fleas—preventing eggs/larvae from becoming adults—the statement that they primarily affect the egg stage is the best description. They do not provide immediate relief from bites, nor do they repel fleas, and they don’t quickly kill existing adult fleas. Used together with adulticides, IGRs help reduce future flea populations by stopping the life cycle.