Which statement is true about using IGRs against flea larvae?

• A. It prevents eggs from hatching
• B. It prevents larva from developing into pupa
• C. It prevents pupa from developing into adult
• D. It prevents adults from laying eggs

Answer: (B)

IGRs, or insect growth regulators, work by disrupting development rather than killing insects outright. They act like a juvenile hormone in fleas, so larvae can’t properly molt to the next life stage. When flea larvae are exposed to an IGR, their progression from larva to pupa is blocked or halted, preventing them from reaching the pupal stage and eventually becoming adults. Because of this, fewer adult fleas emerge to reproduce, which is the main way these products reduce the flea population. Eggs aren’t directly prevented from hatching, and adults aren’t stopped from laying eggs by the IGR itself, which is why the statement about blocking the larva-to-pupa transition best fits how IGRs work.