In flea control, which life stage do insect growth regulators primarily target?

• A. Egg stage
• B. Larval stage
• C. Pupal stage
• D. Adult flea

Answer: (A)

Insect growth regulators work by interrupting flea development rather than killing adults. They mimic natural growth signals, so immature fleas don’t progress to the next stage. For fleas, the cycle goes eggs to larvae to pupae to adults. By preventing eggs from hatching (and sometimes disturbing larval development), IGRs break the life cycle early. That makes the egg stage the primary target, since stopping hatch directly prevents the appearance of larvae and the continuation of the cycle. Adults aren’t the main target of these products, which is why they’re not relied on for immediate kill of mature fleas.