The label is the law. Read your product's label before you mix or apply; the rates here come from the labels listed under Sources.
- Active ingredient
- Cypermethrin (CAS 52315-07-8)
- Chemical class
- Pyrethroid: a synthetic version of the pyrethrins extracted from chrysanthemum flowers.[1]
- Mode of action
- IRAC Group 3A: Sodium channel modulators (nerve action)[3]
- Signal word
- Demon WP Insecticide in Water-Soluble Packets: Warning[2]
How it works
Cypermethrin disrupts the central nervous system of insects; pests that contact or feed on it become paralyzed and die.[1]
It is in IRAC Group 3A with bifenthrin, deltamethrin, lambda-cyhalothrin and permethrin, so moving between these products does not change the mode of action.[3]
Handling the packets
Because the packets dissolve on contact with moisture, the label says to keep them dry until they go into the tank, wear dry gloves, handle them gently so they do not rupture, and store unused packets in the folded foil envelope; add the packets to the water in the sprayer, allow 1–2 minutes for them to dissolve, then agitate.[2]
Where it is used
Demon WP is labeled as a general surface, crack-and-crevice and spot treatment in, on and around buildings and structures, and on lawns, ornamental trees and shrubs around buildings, parks and athletic fields; it may not be used on golf course turf.[2]
For drywood termites and above-ground subterranean termite activity in localized areas of damaged wood, the label directs a 0.1% solution into voids and galleries.[2]
Products and registrations
| Product | Registrant | EPA Reg. No. | Active % | Formulation | Signal word |
|---|---|---|---|---|---|
| Demon WP Insecticide in Water-Soluble Packets[2] | Syngenta Crop Protection | 100-1000 | 40.0% | wettable powder in water-soluble packets (0.33 oz / 9.5 g each) | Warning |
Label rates
| Product | Use | Pests | Rate |
|---|---|---|---|
| Demon WP Insecticide in Water-Soluble Packets | Structural pests, hand equipment (general surface, crack and crevice, spot) | 0.1%: most listed pests including cockroach maintenance, crickets, earwigs, silverfish, ticks. 0.2%: ants, bees, scorpions, spiders, wasps, cockroach clean-out | 1–2 packets per gal of water[2] 1 packet per gallon = 0.1%; 2 packets per gallon = 0.2%. Add the packets intact to water in the sprayer and let them dissolve 1–2 minutes. |
How to apply it, step by step
1. Protective gear
- Mixers, loaders and applicators must wear a long-sleeved shirt, long pants, shoes and socks, and chemical-resistant gloves such as barrier laminate, or nitrile, neoprene or Viton rubber over 14 mils, when using handheld equipment.[2]
- Handle the packets with dry gloves; they dissolve on contact with moisture, and rough handling can split them.[2]
2. Before you spray
- Don't apply it to pets; take birds and other pets out of the area, and cover aquariums and ornamental fish ponds and turn aquarium systems off.[2]
- Keep people and pets out of the area during application.[2]
- Outdoors, apply in calm weather when rain isn't forecast for 24 hours, keep it out of storm drains, gutters and ditches, and don't let it reach blooming plants while bees are visiting.[2]
3. Mixing
- Fill the sprayer half full of water, drop in the intact packet or packets, wait 1 to 2 minutes for them to dissolve, then close and shake the sprayer; finish filling it and shake again before use.[2]
- For general surface, crack-and-crevice and spot treatments the label uses 1 packet per gallon of water (0.1%) or 2 packets per gallon (0.2%).[2]
- Never cut or open a packet, keep unused packets in the foil envelope folded shut, mix only what you need, and don't leave the dilution in the sprayer overnight.[2]
4. Applying
- Shake or re-agitate the sprayer if you stop partway through the job.[2]
- Outdoors, don't spray sidewalks, driveways or patios except as a spot or crack-and-crevice treatment, and don't let any of it reach a drain during or after application.[2]
5. After you spray
- Leave the treated area right after spraying and stay out until the spray has dried.[2]
First aid
- In the eyes, hold the eye open and rinse slowly and gently with water for 15 to 20 minutes, removing contact lenses after the first 5 minutes; on skin, take off contaminated clothing and wash with plenty of soap and water for 15 to 20 minutes.[2]
- If swallowed, call a poison control center or doctor right away, have the person sip a glass of water if they can swallow, and don't induce vomiting unless told to.[2]
- If inhaled, move the person to fresh air and call 911 if they aren't breathing; have the label with you when you call for treatment advice.[2]
Storage, spills and disposal
- Store packets in their foil package in a cool, dry place, not below 32°F, and handle them gently below 50°F so they don't break; don't store diluted spray.[2]
- Sweep up spills on floors or pavement and hold them for proper disposal; never pour leftovers down a drain or sewer, and call your local solid waste agency for options.[2]
- The empty outer foil pouch can go in the trash as long as the packets inside were unbroken.[2]
From the safety data sheet
- The product is a white powder with a slightly aromatic odor; in a fire it can give off irritating and possibly toxic gases.[4]
- Store it in a well-ventilated, secure area out of reach of children and pets, away from food and drink.[4]
- Sweep up spills right away, keep them out of soil, drains and water, scrub the area with detergent, and seal the waste in a container for disposal.[4]
- It is harmful if swallowed or inhaled, irritates eyes and may cause an allergic skin reaction; skin contact can cause temporary itching, tingling, burning or numbness that lasts up to 24 hours.[4]
Safety and environmental hazards
People
The label signal word is WARNING: it causes substantial but temporary eye injury, so protective eyewear is required, and it is harmful if swallowed, inhaled or absorbed through skin; repeated skin contact may cause allergic reactions in some people.[2]
Pets
The label says care should be used to avoid household pets, particularly fish and reptile pets, during application; keep pets off treated areas until the spray has dried.[2]
Bees and pollinators
The 2025 label states it is highly toxic to bees exposed to direct treatment or residues on blooming crops or weeds; do not apply or let it drift onto blooming plants bees are visiting.[2]
Fish and water
The label states it is extremely toxic to fish and aquatic invertebrates; do not apply directly to water or where surface water is present.[2]
Common questions
- How many Demon WP packets per gallon?
- One 0.33-oz packet per gallon makes a 0.1% spray for most listed pests; two packets per gallon makes 0.2% for ants, bees, scorpions, spiders and clean-out treatments.[2]
- Why does Demon WP say WARNING instead of CAUTION?
- Its label states it causes substantial but temporary eye injury, which puts it in the WARNING category; eye protection is required when handling it.[2]
Sources
- University of California Statewide IPM Program, “Home and Landscape Pesticide Active Ingredients Database: cypermethrin.” ipm.ucanr.edu/home-and-landscape/pesticide-active-ingredients-database/active-ingredient-details/?uaiKey=130 (accessed 2026-10-06)
- U.S. EPA Pesticide Product Label System, “Demon WP Insecticide in Water-Soluble Packets label, EPA Reg. No. 100-1000 (EPA-stamped, Sept. 4, 2025).” www3.epa.gov/pesticides/chem_search/ppls/000100-01000-20250904.pdf (accessed 2026-10-06)
- Insecticide Resistance Action Committee, “IRAC Mode of Action Classification Scheme, Version 11.5 (Feb. 2026).” irac-online.org/documents/moa-classification/ (accessed 2026-10-06)
- Syngenta Crop Protection, LLC, “Demon WP Material Safety Data Sheet (Syngenta Crop Protection, revised February 9, 2012; copy hosted by distributor DoMyOwn).” www.domyown.com/msds/Demon%20WP%20Insecticide%20MSDS.pdf (accessed 2026-10-16)