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
- Methomyl (CAS 16752-77-5)
- Chemical class
- N-methyl carbamate insecticide that inhibits cholinesterase.[1]
- Mode of action
- IRAC Group 1A: Acetylcholinesterase inhibitors: carbamates[2][1]
- Signal word
- Golden Malrin RF-128 Fly Killer (alternate brand Starbar Golden Malrin Fly Bait): Caution[1]
What changed in 2025
Under EPA's registration review of methomyl, the product was reclassified as a Restricted Use Pesticide due to hazard to non-target species, and the current label adds that intentionally killing raccoons, skunks, opossums, coyotes, dogs, cats or other non-target animals with it is illegal.[1]
Alternatives for home fly problems
Fly baits built on other modes of action exist, such as spinosad in IRAC Group 5; whatever you buy, check that the label permits residential use.[2]
Where it is used
Because it is now a Restricted Use Pesticide, homeowners cannot legally buy or apply it unless they are certified applicators or working under one's direct supervision.[1]
Bait stations may be used in stables, outside milking parlors, kennels, restaurants, bakeries, supermarkets, warehouses and around dumpsters, secured at least 4 feet above the ground and out of reach of food-producing animals, pets and children.[1]
Products and registrations
| Product | Registrant | EPA Reg. No. | Active % | Formulation | Signal word |
|---|---|---|---|---|---|
| Golden Malrin RF-128 Fly Killer (alternate brand Starbar Golden Malrin Fly Bait)[1] | Wellmark International (Central Garden & Pet) | 2724-274 | 1.0% | granular scatter bait with (Z)-9-tricosene fly attractant | Caution |
Label rates
| Product | Use | Pests | Rate |
|---|---|---|---|
| Golden Malrin RF-128 Fly Killer (alternate brand Starbar Golden Malrin Fly Bait) | Scatterbait around the outside of listed commercial and agricultural sites (certified applicators only) | House flies | 4 oz per 500 sq ft of fly feeding area[1] Reapply daily only when flies eat 4 oz per 500 sq ft in a day, otherwise every 2–3 days. In bait stations: at least 4 feet off the ground, out of reach of animals and children, no more than 1 oz per station. |
Safety and environmental hazards
People
The label signal word is CAUTION: harmful if swallowed or absorbed through the skin. Its note to physicians says methomyl inhibits cholinesterase, early poisoning signs include sweating, headache, nausea, vomiting, blurred vision and muscle twitching, and atropine is antidotal.[1]
Pets
The label says the bait must not be used inside or around homes or anywhere children or pets are likely to be, that children and pets must not be allowed into treated areas, and that using it to kill dogs, cats or wildlife is illegal.[1]
Bees and pollinators
The label directs reporting any harm to bees and other non-target insects to EPA's pesticide incident line; its main wildlife warning concerns birds, fish and mammals.[1]
Fish and water
The label states it is toxic to birds, fish, aquatic invertebrates and mammals, that spilled granules must be collected or covered, and that runoff may harm aquatic organisms; methomyl is also known to leach through soil into groundwater.[1]
Common questions
- Can I still buy Golden Malrin for my barn?
- Only if you are a certified applicator or working under one's direct supervision; the current label restricts sale and use to them because of hazards to non-target animals.[1]
- Is methomyl fly bait safe around dogs?
- No. The label forbids using it anywhere pets are likely to be present and says to keep children and pets out of treated areas.[1]
Sources
- U.S. EPA Pesticide Product Label System, “Golden Malrin RF-128 Fly Killer label, EPA Reg. No. 2724-274 (EPA-stamped, Nov. 25, 2025; Restricted Use reclassification).” www3.epa.gov/pesticides/chem_search/ppls/002724-00274-20251125.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)