Malathion

How it works

Malathion binds to the enzyme that normally ends a nerve signal, so the insect's nerves keep firing and it can no longer move or breathe normally.^[1]

It is IRAC Group 1B, the organophosphates; people, pets and other animals are affected the same way if they are exposed to enough of it.^[3][1]

Storing the concentrate

NPIC notes that malathion can become more toxic if it sits a long time, especially somewhere hot, and the label says never to heat it above 131°F and to keep it in a secure, dry place.^[1][2]

In soil and water

In soil, half of it is gone in about 17 days; in water, in 2 to 18 days depending on temperature and pH.^[1]

Where it is used

It is for outdoor use around the home only and must not be used on lawns or applied to driveways, sidewalks and patios except as a spot or crack-and-crevice treatment.^[2]

On flowers and shrubs such as azaleas, camellias, chrysanthemums, evergreens and roses it is a spot treatment only, at no more than two applications a year at least 10 days apart.^[2]

Every crop has a minimum wait between the last spray and harvest, from 0 days for potatoes and 1 day for beans, squash and tomatoes to 7 days for cabbage, kale and radishes and 14 days for lettuce.^[2]

Products and registrations

Label rates

How to apply it, step by step

Steps for Spectracide / Super K-GRO Malathion 50 Insect Spray Concentrate (50% malathion), EPA Reg. No. 46515-19, taken from its label^[2]. Other products with this active ingredient have their own labels; follow yours.

1. Protective gear

• Avoid contact with skin, eyes and clothing; it is harmful if swallowed or absorbed through skin and moderately irritating to the eyes.^[2]
• Wash with soap after handling and before eating, drinking, smoking or using the toilet, and wash contaminated clothing before wearing it again; use it only with adequate ventilation.^[2]

2. Before you spray

• It's for outdoor use around the home only, not on lawns, and not on Boston, maidenhair or Petris ferns, Crassula or petunias.^[2]
• Don't spray within 25 feet of lakes, ponds, streams or wetlands, onto or toward drains and gutters, or when a storm likely to cause runoff is forecast within 24 hours.^[2]
• Test a hidden spot first if the spray might hit vinyl siding, and recheck in a few hours for staining.^[2]
• To protect pollinators, the label suggests spraying in the evening or at night when they aren't foraging and avoiding flowering plants.^[2]

3. Mixing

• Mix the label's amount for your pest in water in a tank sprayer until the mixture is uniform: for example, 1 tablespoon per gallon for bagworms, boxelder bugs, Japanese beetle adults, mealybugs, spider mites, thrips and whiteflies, and 1 1/2 to 2 tablespoons per gallon for black, oystershell and soft brown scales on ornamentals.^[2]

4. Applying

• Start when insects first appear and spray thoroughly, covering both upper and lower leaf surfaces and other infested parts.^[2]
• Keep people and pets out of the area during application, and don't spray in a way that drifts onto anyone.^[2]
• Don't spray sidewalks, driveways or patios except as a spot or crack-and-crevice treatment, and don't spray to the point of runoff.^[2]

5. After you spray

• Keep people and pets out of the treated area until the spray has dried.^[2]
• On vegetables, wait the label's pre-harvest interval before picking: for example, 14 days for lettuce, 7 days for radishes, 3 days for peas, and 1 day for squash and tomatoes.^[2]

First aid

• If swallowed, call a poison control center or doctor immediately; don't induce vomiting unless told to, and don't give the person any liquid.^[2]
• On skin or clothing, take off contaminated clothing and rinse skin with plenty of water for 15 to 20 minutes; in the eyes, rinse slowly and gently for 15 to 20 minutes, removing contact lenses after the first 5 minutes.^[2]

Storage, spills and disposal

• Store it in the original container in a secure, dry place, never heat it above 131°F, and don't keep it for long periods above 77°F.^[2]
• Use up the product according to the label; if you can't, take leftovers to a household hazardous waste or pesticide disposal program, never down a drain, and put the empty container in the trash or recycling.^[2]

From the safety data sheet

From the product's safety data sheet^[4]. Where it and the label differ, the label is the law.

• The concentrate is a clear, light yellow to amber liquid with a mercaptan and solvent smell; it is a flammable liquid with a flash point of about 120 °F (49 °C).^[4]
• The SDS uses the signal word Danger: it may be fatal if swallowed and it enters the airways, causes eye and skin irritation, and may cause respiratory irritation, drowsiness or dizziness.^[4]
• If swallowed, don't induce vomiting unless medical personnel tell you to; if breathing is difficult, move to fresh air; after skin contact, wash with plenty of water for 15 minutes.^[4]
• Contain or absorb spills with inert material, scoop them into a disposable container, and don't flush them to a sewer or let them reach waterways.^[4]
• Keep it away from heat, sparks and open flames, and store it locked up in a cool, well-ventilated place with the container tightly closed.^[4]

Need the amount for your sprayer? Use the mixing calculator, which works from the same label rates.

Safety and environmental hazards

People

The label signal word is CAUTION: harmful if swallowed or absorbed through the skin and causes moderate eye irritation, and it carries a physician's note that it is a cholinesterase inhibitor. People made sick by malathion had nausea, vomiting, tremors, cramps, weakness, shortness of breath, slowed heart rate and diarrhea; EPA found suggestive evidence of carcinogenicity but not enough to assess human cancer potential.^[2][1]

Pets

The label says to keep people and pets out of the area during application and off treated areas until sprays have dried. Pets can be poisoned by touching or eating freshly sprayed plants, with signs like those in people.^[2][1]

Bees and pollinators

The label states it is highly toxic to bees exposed to direct treatment on blooming crops or weeds, forbids spraying while bees are visiting, and on fruit trees bans spraying from 3 days before bloom until petal fall is complete.^[2]

Fish and water

The label says it is toxic to fish and aquatic invertebrates and must not be applied within 25 feet of lakes, streams, wetlands, ponds or other aquatic habitat; NPIC adds that malathion moves quickly through soil and turns up in streams and sometimes well water.^[2][1]

Common questions

How much malathion per gallon of water?

It depends on the pest: 1½ to 2 teaspoons for aphids, 1 tablespoon for most other listed garden pests, and 1½ to 2 tablespoons for scales.^[2]

Can I use malathion on my lawn?

No. The Spectracide malathion label says not to use it on lawns.^[2]

How long after spraying malathion can I pick tomatoes?

The label sets a 1-day pre-harvest interval for tomatoes; lettuce needs 14 days and cabbage 7.^[2]

Is malathion safe for bees?

No. It is highly toxic to bees, so never spray blooming plants or spray while bees are visiting.^[2][1]

Sources

1. National Pesticide Information Center, “Malathion General Fact Sheet.” npic.orst.edu/factsheets/malagen.html (accessed 2026-10-06)
2. U.S. EPA Pesticide Product Label System, “Malathion 50 Insect Spray (Spectracide Malathion Insect Spray Concentrate) label, EPA Reg. No. 46515-19 (EPA-stamped, May 28, 2024).” www3.epa.gov/pesticides/chem_search/ppls/046515-00019-20240528.pdf (accessed 2026-10-06)
3. 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)
4. Spectrum Brands (United Industries), “Spectracide Malathion Insect Spray Concentrate Safety Data Sheet (Spectrum Brands, July 16, 2019; EPA Reg. No. 46515-19-8845, a distributor registration of the page's 46515-19 label; copy hosted on The Home Depot's product-document server).” images.homedepot-static.com/catalog/pdfImages/4b/4be8ce78-9751-4f44-abf2-8dc6cab03c8a.pdf (accessed 2026-10-17)