Spinosad Insecticides: How to Use Them Safely

One of the most frustrating aspects of gardening is dealing with pests. Before you throw in the trowel once and for all, you need to hear about spinosad spray. It’s an organic form of pest control derived from a bacterium called Saccharopolyspora spinosa.

You may have heard of Bacillus thuringiensis, or BT, which is another godsend for organic gardeners. There are many pests BT can’t kill. Spinosad will kill most of those. When you use both of these together on your vegetables or other produce, your garden will remain almost completely pest-free.

Spinosad is highly toxic to bees when it’s wet, so you need to be strategic about the time of day you apply it. Once dry, it can kill chewing pests for up to four weeks.

What Is Spinosad?

Spinosad is made of chemicals called spinosyn A and spinosyn D. These chemicals are derived from the fermentation juices of soil bacteria, which means the product is completely naturally derived.

Spinosad is a relatively new insect killer, having been approved by the US Environmental Protection Agency (EPA) in 1997. In 2003, it was officially given organic status by the USDA National Organic Program (NOP). With these seals of approval, you can safely use them in vegetable gardens and on your ornamental plants.

Since spinosad is natural, it’s safe to apply on food crops. But you should wash off all your food after you harvest it to be safe. You can spray it on leaves or fruits, or wherever you spot insect pests.

The most popular form of spinosad is a spray that can be applied directly to plants and will dry within a few hours. It’s also available in the form of dust and granules. Dust may be easier to find than granules. Granules are typically sold as a fire ant killer. Ant killer usually has bait in it, so the ants will pick up the granules and take them into the nest, so it may not be suitable for organic gardening.

You may also find other synthetic pest control products that list the active ingredient spinosad in them.

How Does Spinosad Kill Insects?

Saccharopolyspora spinosa is toxic to pests and affects their nervous systems. Once spinosad is applied to the plant, insect larvae will feed on the substance and die within a day or two. Spinosad will cause the insect’s muscles to flex uncontrollably, which leads to paralysis and eventually death. It’s most effective when the larvae eat it, but simply walking over it is usually enough to do some damage.

Spinosad can kill a wide variety of insects, including fire ants, fruit flies, leafminers, mites, mosquitoes, spider mites, and thrips. It is generally used on vegetables and fruit along with other garden species. Many organic gardeners use BT to take care of caterpillars and use spinosad spray for everything else.

This garden insect spray can harm beneficial insects such as bees, but we’ll get into the details of that in a bit.

Benefits

An obvious benefit is that spinosad kills insects that BT doesn’t, such as thrips, flies, and fire ants. It also lasts much longer than BT. It can last up to four weeks unless it gets washed away by rain or the garden hose before then.

The two chemicals that spinosad is made of come from the fermentation juices of bacteria, so you’re fighting nature with nature. It’s OMRI-listed as organic, meaning it’s deemed organic by the Organic Materials Review Institute.

Spinosad is rapidly broken down by sunlight and water and disperses in the soil, so you don’t have to worry about it polluting groundwater or the soil. Some chemical pesticides can stay in the environment for up to a year, causing them to build up in the soil and in groundwater. Fortunately, we don’t have to worry about this with spinosad.

Drawbacks

The biggest drawback of spinosad is that it’s highly toxic to bees while the spray is wet. Timing is everything when it comes to spinosad. Bees are most active during the day, usually mid-morning to late afternoon. Apply spinosad spray in the evening or very early morning to allow plenty of time to dry. The spray should take no more than three hours to dry completely.

Since spinosad spray is considered safe to use around bees once it’s dried, the dust and granules can be considered safe, too. Still, you should wait until the bees aren’t active to take precautionary measures. Take the extra step and avoid applying spray, dust, or granules on flowers or anywhere else you see bees frequently land.

Another concern is that spinosad is moderately toxic to earthworms. You can avoid harming worms by only applying it to plants as needed. Using granules for fire ant treatment will certainly pose a risk to the worms, so try to avoid using it around your garden beds or other places where you’d like to keep the worms safe.

Finally, spinosad is slightly toxic to humans, animals, birds, and fish. This toxicity is incredibly low. If it comes into contact with your skin or eyes, the only problems you should experience are irritation and redness. Animals may have a similar reaction if they should come into contact with it.

When using spinosad, avoid letting it touch your skin. Wearing safety goggles while applying it, especially if you’re using it in dust form, will protect you and keep you safe from irritation.

Be mindful of when and where you apply it, and only use it when necessary so you can keep worms, bees, and other animals safe.

How To Use Spinosad Spray

Spinosad liquid spray comes in two forms, ready-to-use (RTU) and concentrate. You should be able to find these in the gardening department of home improvement stores.

RTU spinosad sprays are the easiest to use in home gardens because you can begin spraying as you open the bottle. It won’t require any mixing or measuring. However, you should still read the label of your RTU product to make sure you use it correctly.

Spinosad concentrates are mixed with water before application. Mix carefully to dilute it to a safe amount so you won’t end up harming the wrong insects or yourself. The label of the product will tell you the exact measurements.

Measure out the proper amount of liquid and mix it into water. It’s usually a few tablespoons per gallon, but this may change depending on the product. Once it’s properly proportioned, spray on your plants as directed.

For both kinds of spinosad spray, apply it to the tops and bottoms of the leaves and on stems. Spray it wherever you see pests and larvae. Remember, avoid spraying flowers to keep the bees safe, and avoid spraying the soil if you can.

You can spray larvae directly, but it’s when they eat sprayed leaves that you’ll find it to be the most effective. If you see eggs on your plants, spray again in a few days after the eggs have hatched.

How To Use Spinosad Dust

Spinosad dust will either come in a bag or in a squeezable container. If you have the container, simply squeeze it so the dust comes out. Apply it to the tops and bottoms of leaves just as you would with spray.

You may find it a bit trickier to apply if it comes in a bag. Find a squeezable container you can clean and repurpose for spinosad application, or use gloves and sprinkle it with your hands. To prevent skin irritation, wear gloves and cover your arms to reduce exposure when you’re handling dust, regardless of its packaging. It’s advisable to wear a mask as well to avoid inhaling the dust.

Spinosad granules are easy to apply. Follow the directions on the label to find out how much to apply to a specific area. Since it’s often used to control ants, you’ll probably find the ratio for how much to apply per 1,000 square feet. If you apply the granules by hand, be sure to wear gloves to avoid skin irritation.

Although dried spinosad is safer for beneficial insects than in wet form, you should wait for the evening or early morning to apply dust and granules as an extra safety precaution so you can lower their chance of exposure.

Spinosad Alternatives

To protect the beneficial insects like bees in your garden, it’s best to opt for safer environmental controls first before using spinosad. Check out the 9 Pollinator-Safe Pest Control Methods for Your Garden you can try.

If these methods don’t work and you need to reach for spinosad, use it carefully. Follow the steps above and cover your crops with floating row covers for a few hours when you’re done. This will stop bees from interacting with the spinosad while it dries.

Frequently Asked Questions