Skip to Content

Spinosad: Finally! A Safe Insecticide for Organic Growers

Spinosad: Finally! A Safe Insecticide for Organic Growers

If you are in need of a reliable and environmentally-friendly method for pest control, we would like to introduce spinosad. It is a secure insecticide used by organic farmers and has proven to be highly effective in eliminating pests.

What is spinosad? Spinosad is an all-natural substance that consists of soil bacterium that is deadly to bugs. The formula contains spinosyn A and spinosyn D, organic chemicals found in Saccharopolyspora spinosa. Applying it on and around gardens and ornamental plants is a sure way to kill problematic insects.

Read on below to learn all about this relatively new organic, grower-friendly insecticide!

Spinosad Brand Names

Monterey Garden Insect Spray is the number one brand name insecticide with spinosad as the main active ingredient.

Other popular brand names that utilize spinosad include Bulls-Eye Bioinsecticide and certain Fertilome products, such as their Natural Guard line.

Comfortis and Trifexis are two spinosad brand-name products that treat fleas on pets like cats and dogs. Natroba is a powerful brand-name product for treating head lice in humans.

How Does Spinosad Work?

Spinosad affects insects in a harsh and aggressive manner; it attacks their central nervous system and overrides it.

When insects come in contact with spinosad, they lose the ability to control their muscles and nervous systems. Spinosad causes insects to spasm and flex until they are paralyzed, dead, or both.

What Does Spinosad Kill?

Spinosad is a potent and fast-acting form of organic pest control — there is no question about it. 

Unfortunately, it does not kill all problematic insect species like aphids, mealy bugs, whiteflies, cicadas, and some grasshoppers.

Common insects that spinosad does kill include:

  • Ants
  • Bees
  • Beetles
  • Borers
  • Butterflies
  • Caterpillars
  • Flea
  • Fruit flies
  • Leafminers
  • Lice
  • Mites
  • Mosquitoes
  • Moths
  • Spider mites
  • Thrips

How Long Does It Take Spinosad To Work?

Spinosad generally kills insects within 24 to 48 hours of them coming in contact with and/or ingesting the product.

After spinosad is applied, it only lasts for a short window of time before it loses its effectiveness and must be applied again.

Depending on the product, spinosad insecticides last anywhere from two days to four weeks before they stop working altogether.

Is Spinosad Systemic?

Spinosad has systemic properties, which means that just the tiniest bit of product can protect your garden variety plants from common pests like mites and flies.

Spinosad is not absorbed much through the skin of insects. Rather, it is ingested and passes through the body (where it does its damage).

Is Spinosad Organic?

Spinosad is organic. The formula for the ingredients, spinosyn A and spinosyn D, was discovered in the 1980s and is still somewhat less known than other forms of organic and inorganic pest control.

The active ingredients of spinosad are all-natural chemicals and safe to use in organic gardens.

Does Rain Wash Off Spinosad?

Rain can wash off spinosad if it comes down hard enough. That said, most spinosad products are quite resistant to rain compared to other insecticides.

For best results, only apply spinosad products when rain is not expected for the next 24 hours.

What Plants Can You Use Spinosad On?

Spinosad is an organic pest control solution that works well on:

  • Garden variety vegetables
  • Fruits such as strawberries, raspberries, and blueberries
  • Fruit and nut trees
  • Citrus trees such as lemons, oranges, and mangos
  • Ornamental trees and shrubs
  • Lawns and ornamental grasses

How Often Should You Use Spinosad?

Spinosad can be applied much more frequently than harsh chemical-based insecticides. You can apply it as often as once per week.

Remember, the insect-killing effects of spinosad pest control products decrease slightly after just 8 hours to 1 or 2 days but remain potent for several weeks.

When To Apply Spinosad

The best time to apply spinosad products to your plants, trees, shrubs, and lawn is early in the morning or late in the evening. 

The main point is to apply the spinosad during times when bees and other beneficial insects that can be harmed aren’t out in numbers and active.

How To Use Spinosad in the Garden

Spinosad is a natural pesticide that is best applied via spray. Most spinosad products need mixing with water, according to their instructions.

Once mixed, simply aim for the base and leaves of the plants, as well as the soil around them, and spray it thoroughly with spinosad.

Note: It is recommended to avoid using more than 3 gallons of spinosad solution at a time per 1,000 square feet of garden.

A young woman spraying plants in a polytunnel greenhouse.

Spinosad Soil Drench

A soil drench is the act of saturating your plant’s soil and root zone with water. The technique is often used as a means to provide an undernourished plant with food and moisture. 

A spinosad soil drench is a soil drench with a solution of water and spinosad. The point of a spinosad drench is to kill insects that dwell in the ground or feed on your plant’s roots.

To do a spinosad soil drench:

  • Choose a 1- or 2-gallon container, and fill it with 1 gallon of water
  • Mix 3 to 5 tablespoons of spinosad into the water
  • Dump the solution near the central stalk of the plant(s) whose soil you are drenching

Spinosad Indoor Use

Organic pesticide products consisting of spinosad are typically perfectly safe for indoor use. 

Applying spinosad to indoor plants is simple — just spray it on the tops and bottoms of the plants’ leaves as well as their central stalk and branches.

Spinosad vs. Bt

Spinosad and Bt are both generally considered safe pesticides.

There are two main differences between the two besides their chemical makeup: Bt has an active 2-day window for killing insects, and it mainly targets caterpillars.

Spinosad, on the other hand, kills insects for up to 4 weeks, depending on the product. It is also much less selective than Bt, killing far more of the common pest insect species than just caterpillars.

Spinosad vs. Neem Oil

Neem oil is one of the most powerful essential oils used as a pest control home remedy that exists. However, it does have its limits: it kills insects by suffocating them.

That means that while it is still a potent solution, it is far less effective than spinosad. 

To kill the same amount of pests with neem oil as you could with spinosad, you must re-apply neem oil several times over a course of weeks.

Spinosad for Dogs

Spinosad products like Comfortis, which are used for the treatment of fleas, are considered safe for use on your pets.

It isn’t recommended to use Comfortis or other spinosad for pets until they are around five pounds or more. For many dogs, that’s around 2 months old.

Spinosad for Cats

Cat owners, like dog owners, often rely on spinosad products, such as Comfortis for cats, to treat fleas on their furry buddies.

Your cat needs to be approximately 3 to 4 months old before it is generally considered safe to apply spinosad for cats. 

Spinosad Price

Spinosad for plants, such as Monterey Garden Insect Spray, has a current price tag of around $20 per 16 fluid ounces. 

Spinosad for humans, such as Natroba, costs up to approximately $350 per 120ml container.

(These prices are subject to change, of course. They are just given to give you an approximate idea of costs.)

Where To Buy Spinosad

Spinosad is available at local garden centers and big box stores like Walmart, Home Depot, and Lowes. 

Or, if you prefer, you may also shop for and purchase spinosad products from the comfort of your home through online retailers like Amazon and eBay.

Monterey Garden Insect Spray

One of the most trusted and proven spinosad products for pest control is Monterey Garden Insect Spray. It comes in a concentrated form in a 16-fluid-ounce container.

The formula works quickly at killing most common pests and is odorless. Further, it works well with practically any type of sprayer, including hand-held, pump, backpack, trigger, and hose-end applications.

To use, simply read the directions on the label and follow the instructions. Mix the correct amount of concentrate into your sprayer along with the correct amount of water.

Apply the solution to the plant’s leaves on both sides, its branches, the main stalk, the base of the plant, and the soil around it.

For a spinosad soil drench, simply mix the solution in a gallon jug and dump it onto the soil around the plant rather than spraying it. 


Spinosad is safe and powerful pest control solution for organic growers and ordinary house plant parents alike.

Simply mix a few tablespoons of spinosad with water and spray it onto the leaves and stalks of plants, or drench the soil with it, and enjoy fast and fatal results.

Keep in mind that the time of day you use spinosad is crucial, as you may harm beneficial insects like butterflies and bees if you use it after 8 or 9 a.m. or before the sun starts to set.