Can You Mix Bt And Spinosad?

If you're dealing with a pest infestation, you just want to get rid of the pests ASAP so that you can save your precious plants. You might get the idea of mixing two insecticides like Bt and Spinosad together to get better and faster results. But is this a good idea? We asked the experts and here's their answer.

It is not recommended to mix Bt and Spinosad in one spray. Spinosad, being a more powerful insecticide, might cancel out Bt and neutralize its effects in your plants. It is best to rotate the use of these two natural insecticides to help you manage the pests that you want to get rid of in your garden.

Keep on reading to know more about these two natural pesticides and how you can use both to maximize each of the benefits that they have to offer. We'll also tell you how Spinosad and Bt work and which one is better between the two. Let's delve in!

Farmer is preparing mixture of water and botanical solutions of pesticide in plastic knapsack sprayer. mixes colored liquid substances with different densities. Can You Mix Bt And Spinosad

Mixing Bt and Spinosad

Nobody wants to have pests lingering in their gardens and property. When there's a pest infestation in your home, you want to have it controlled right away.

So, you try different approaches to manage the situation until you resort to the use of pesticides. But sometimes one insecticide doesn't seem enough to eliminate those disgusting insects that threaten to do more damage to your plants.

That's why it's understandable if you have this idea of mixing two insecticides such as Bt and Spinosad especially if they target the same pests. You might be thinking this would help solve the problem faster and more effectively since you're using the power of not just one but two insecticides.

When you think about it, it is also supposed to be a more convenient and efficient way of treating pests since you only have to do the application once for the two insecticides.

However, experts don't support this idea. In the case of Bt and Spinosad, the former doesn't have enough staying power once applied to the plants. It could be neutralized by the latter which is a more powerful pesticide.

In other words, Spinosad could cancel out the beneficial effects that Bt has to offer so that's defeating the purpose of using Bt in the first place.

Farmer hand pouring chemical insecticide liquid acid into bottle cap

Rotate Insecticide Application

Be careful also because indiscriminate use of pesticides could result in insecticide resistance among your target pests. Instead of resolving the dilemma once and for all, you might end up with a bigger problem.

What you can do instead is to create a rotation program for the insecticides that you're using. Alternate the use of a selective insecticide such as Bt and a broad-spectrum insecticide like Spinosad.

This allows you to harness the synergy between Bt and Spinosad which will result in an effective pest control treatment.

The key is not in mixing the two insecticides but in alternating their use. Schedule them at least a week apart until you're able to control the pests in your area.

Pesticide treatment, pest control, insect extermination on fruit trees in the garden, spraying poison from a spray bottle

How does Spinosad work?

Spinosad is a natural pesticide. Its active ingredients are derived from the fermentation of the soil bacterium Saccharopolyspora spinosa which produces two chemicals, spinosyn A and spinosyn D.

These chemicals are toxic to a wide variety of insects such as caterpillars, thrips, leafminers, fruit flies, ants, and mosquitoes.

They enter the pests' bodies when they get into direct contact with the insecticide. These are neurotoxins that affect the insects' nervous system causing involuntary muscle control, paralysis, and ultimately, death. The pests can be killed within one to two days.

Some Spinosad insecticides are absorbed by the plant which gives it prolonged protection especially against sucking pests.

It is safe to use indoors and outdoors because it has a low level of toxicity since it is made of natural ingredients. You can apply it to ornamental plants and edible crops. It is available in different formulas - ready-to-use spray, concentrate, or granules.

Check out this pesticide with Spinosad concentrate on Amazon.

Be careful during application though especially when applying Spinosad to your outdoor plants. Being a broad-spectrum insecticide, it might hurt some beneficial creatures for your garden like bees and earthworms.

protecting plant with insecticide sprayed using pressure sprayer

How does Bt work?

Bt or Bacillus thuringiensis is another natural insecticide that comes from the Bacillaceae family. Like Spinosad, this bacteria can also be found in the soil.

Its spores contain proteins that are toxic to a particular group of pests only. It is highly selective in the insects that it targets. Specific Bt types target particular pests.

For example, you use:

  • Bt israelensis for gnats, mosquitoes, and flies that are still in their developing stages,
  • Bt santiago for the larvae of beetles,
  • and Bt aizawai for caterpillars of moths.

Bt needs to be ingested to work and it mainly targets the pests' larvae or immature form.

When you apply it to the plant and the pest sucks on it, the toxins in this insecticide would be dissolved and attack the insect's gut cells.

They would punch holes in the gut lining and the Bt spores would germinate inside, leading to starvation, infection, and the insect's death. This might take one to five days.

Bt is only toxic to the pests that they target. Other creatures like aquatic animals, mammals, and humans won't be able to activate them in their guts because of the incompatibility of pH levels.

Thus, Bt presents no harm to other living organisms other than its target pests. It is also safe for the environment since it breaks down easily.

Bt can be used on ornamental plants and crops. It is available in different formulas that makes it easy to use. However, Bt can be toxic to some beneficial insects such as honeybees and some nematodes so exercise proper care when you apply this insecticide in your garden.

Click this link to find this Bt worm and caterpillar killer on Amazon.

protecting plant from diseases, using pressure sprayer

Is Bt or Spinosad better?

Some may wonder which is better to use between the two - Bt or Spinosad?

Both are safe to use. Since they are both natural pesticides, they have low toxicity levels for humans, wildlife, and the environment. They are also available in different product formulas for your convenience and ease of application.


Spinosad works fast and can eliminate pests in one to two days. It also offers protection for a month. Its being a broad-spectrum insecticide is both its strength and weakness, depending on how you look at it.

On one hand, it can kill different species of pests so it will get rid of pests you don't know you had in your plants. On the other hand, Spinosad can also hurt beneficial insects in your garden so you have to apply it carefully and be mindful of the time of the day when you use it when those insects are less active.


Meanwhile, Bt is very specific in the pests that it targets. Again, this is also an advantage and disadvantage in itself.

This means you won't hurt the non-target organisms in your garden. It won't hurt beneficial insects around it. There's specialization so you know which one to use when dealing with a particular pest concern.

However, it also presents limitations in the variety of pests that you can use it against. You would have to use a different pesticide for other insects that it cannot kill.

Bt isn't also as fast-acting as you would want an insecticide to be. It might take five days before you see the results. Its protection on your plants also doesn't last as long as Spinosad. It is easily broken down by sunlight.

In the end, you get to choose which one would suit for particular pest control need. If the infestation is not yet serious, you can use Bt. But if the situation calls for a more aggressive solution, then you can use Spinosad. Or better yet, use them in rotation so that you'll enjoy a pest-free garden in a short time.

man pouring milky white chemical on measuring cup. Can You Mix Bt And Spinosad

Final Thoughts

It is by rotating the use of Bt and Spinosad wherein you can harness the benefits of these insecticides to help you make your garden pest-free. Use them alternately for effective pest control management.

If you want to read about other insecticides for your DIY pest control treatment, feel free to visit the following posts:

Can Neem Oil Be Used Indoors?

Can You Mix Sevin Dust With Water? [And How To]