How do fleas die after applying drops? - briefly
Insecticidal drops deliver neurotoxic chemicals that penetrate the flea’s exoskeleton, disrupt nerve transmission, and cause rapid paralysis and death within minutes. The agents act systemically, impairing the central nervous system and resulting in irreversible failure of vital functions.
How do fleas die after applying drops? - in detail
The lethal process begins when the liquid formulation contacts the animal’s skin. The solvent spreads across the fur, reaching the flea’s exoskeleton. Active compounds—commonly fipronil, imidacloprid, selamectin, or nitenpyram—penetrate the cuticle by diffusion or by being ingested during the flea’s grooming activity.
Once inside the insect, the chemicals act on the nervous system:
- Fipronil blocks GABA‑gated chloride channels, causing uncontrolled neuronal firing.
- Imidacloprid binds to nicotinic acetylcholine receptors, resulting in persistent stimulation and eventual paralysis.
- Selamectin opens glutamate‑gated chloride channels, leading to hyperpolarization of nerve cells.
- Nitenpyram rapidly interferes with nicotinic receptors, producing swift knock‑down.
The disruption of neurotransmission produces muscle spasms, loss of coordination, and cessation of feeding. Fleas become immobilized within minutes to a few hours, depending on the compound’s potency and the ambient temperature. Immobilization prevents blood‑meal acquisition, leading to rapid dehydration and metabolic failure. Death typically occurs within 24 hours for most adult fleas; eggs and larvae are affected indirectly as the adult ceases to lay viable eggs.
Factors that modify the timeline include:
- Dose applied – higher concentrations accelerate absorption and toxicity.
- Flea life stage – larvae and eggs are less directly exposed; they die when the environment becomes inhospitable.
- Environmental temperature – warmer conditions increase chemical diffusion rates.
- Resistance levels – populations with documented resistance to a specific ingredient may require alternative products.
The combined effect of neurotoxic action, paralysis, and inability to feed ensures that the flea population on the host collapses rapidly after the spot‑on application.