🧪 Active Ingredient Profile
Pyriproxyfen (Nylar) — Long-Lasting IGR for Fleas & Mosquitoes
Insect Growth Regulator (Juvenile Hormone Analog) · CAS 95737-68-1
Pyriproxyfen (Nylar) is the second-generation juvenile hormone mimic after methoprene — more stable, longer-lasting, and effective at lower concentrations. It's the preferred IGR in many professional flea programs and is widely used for mosquito larval control.
Mode of Action
Highly potent juvenile hormone mimic — more stable UV-stable and longer-lasting than methoprene; prevents larval maturation and induces sterility in adults at low doses
🦺 Personal Protective Equipment (PPE)
Required PPE varies by formulation and application method. Always read the product
label — the label is the law and overrides general guidance.
- Standard gloves
- Low toxicity — minimal PPE required
- Safe around mammals — targets only juvenile insect hormones
⚠️ Label compliance: The product label is a legal document under FIFRA.
Applying any pesticide in a manner inconsistent with its label is a federal violation.
📋 Application Best Practices
- Read the full label before each use — formulations change and label requirements may differ from previous products you've used.
- Apply at the right rate — more is not more effective. Over-application wastes product, creates unnecessary exposure, and is illegal.
- Target harborage and entry points, not just visible pest activity. Treating where pests hide is more effective than treating where you see them.
- Record the application — note the product, rate, area treated, and date. Required for commercial applications; best practice for homeowners.
- Ventilate the treatment area after application and before re-entry.
💡 Storage: Store in original container, away from children, in a cool dry location. Never transfer to food or beverage containers. Check local regulations for disposal — most areas have household hazardous waste collection events.
❓ Frequently Asked Questions
Q: Is pyriproxyfen safe for pets?
Follow the product label. Keep pets out of treated areas until completely dried (2–4 hours for sprays). Once dry, treated surfaces pose minimal risk to dogs and cats.
Q: Can I use pyriproxyfen indoors?
Check the specific product label — formulations vary. Baits and dusts often have indoor labeling; concentrates and granulars are typically outdoor.
Q: How long does pyriproxyfen last after application?
Residual varies by formulation, surface type, weather, and UV exposure. Indoor applications last longer than outdoor. Check the product label for re-application intervals.
Q: What should I do if exposed?
Remove contaminated clothing, wash skin with soap and water. For eye contact, rinse 15–20 minutes. For ingestion or severe symptoms, call Poison Control (1-800-222-1222). Have the product label available.
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Reviewed by Derek GiordanoContent reviewed by a licensed pest management professional and cross-referenced against EPA, university extension, and manufacturer technical data. Last reviewed: April 2026.
