How do flea drops kill them? - briefly
Flea drops contain insecticidal agents such as imidacloprid or pyrethrins that interfere with the flea’s nervous system, leading to rapid paralysis and death. The chemicals are absorbed through the cuticle and spread quickly throughout the insect’s body.
How do flea drops kill them? - in detail
Flea treatment drops contain insecticidal agents that act on the nervous system of adult fleas, larvae, and eggs. The active compounds—commonly neonicotinoids, insect growth regulators (IGRs), or organophosphates—penetrate the cuticle after topical application and enter the haemolymph.
Neonicotinoids such as imidacloprid bind to nicotinic acetylcholine receptors in the central nervous system. This binding prevents normal neurotransmission, causing continuous stimulation, paralysis, and rapid death. The effect occurs within minutes of contact.
Insect growth regulators, for example methoprene or pyriproxyfen, mimic juvenile hormone, disrupting metamorphosis. Larvae ingest residues while feeding on contaminated adult flea debris; development stalls at the pupal stage, preventing emergence of new adults. This action does not kill existing adults directly but reduces population renewal.
Organophosphate agents, less common in modern products, inhibit acetylcholinesterase, leading to accumulation of acetylcholine, uncontrolled nerve firing, and fatal convulsions.
The delivery system ensures distribution across the host’s skin and fur. Lipophilic solvents facilitate spread, while the volatile carrier evaporates, leaving a residue that remains active for several weeks. Fleas acquire the toxin through direct contact, grooming, or ingestion of contaminated blood.
Key points of the mode of action:
- Rapid neurotoxic effect on adult fleas (nicotinic receptor agonists).
- Disruption of developmental pathways in immature stages (juvenile‑hormone analogues).
- Persistent residue on hair shafts and skin surface.
- Continuous exposure through host grooming behavior.
Overall, the combination of immediate neurotoxicity and long‑term developmental inhibition results in swift elimination of existing fleas and suppression of future infestations.