Here’s the real deal on using insecticide in your garden
It’s a bug-free—not bee-free—zone
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Few sights annoy a gardener more than insect pests devouring their lovingly tended plants. All your money, time, and hard work can be wasted if hungry insects get out of control. Luckily, there are ways you can fight back to save your precious plants.
One of my earliest memories is helping my great-grandfather in his vegetable garden. He often had me remove caterpillars from the cabbages. This kept 3-year-old me out of trouble, but little did I know, it was also part of a sophisticated pest control strategy. He would just have called it gardening.
Given the vast range of options available, choosing the right way to stop insect pests is tough. You need something that solves the problem and is safe for the people and pets who use your yard. Is the answer to your garden woes insecticide? Maybe. Just remember that by helping one plant, you could also hurt the health of your garden and the wider environment.
Here are the basics of what you need to know when it comes to using insecticides.
Are neonicotinoid insecticides safe?
Insecticide manufacturers consider several factors when developing new pesticides. The ideal product is toxic, but only to the pest, isn’t harmful to humans and other animals, and needs time to work before it breaks down.
As assessed by the EPA, most modern, readily available insecticides have a low risk of damaging human health.
That said, insecticides are designed to kill things, so on a certain level, they’re harmful and should always be used with care. Neonicotinoid insecticides (neonics), specifically, are widely used because they, at least partially, fit this profile. They have a nicotine-like structure, but are only toxic to insects, not mammals and birds. They also stick around for long enough to be effective. For these reasons, they’ve been popular with farmers and gardeners since the 1990s.
If neonics are applied directly to plants, they kill insects on the plant surface. Some neonics dissolve easily in water and move into plants through the roots to kill sap-sucking aphids, and caterpillars and beetles that munch on the leaves. If applied to the soil or lawns, they also target burrowing pests like lawn grubs.
This all sounds good, but sometimes they miss the intended target.
Do neonicotinoid insecticides harm bees?
Bee safety is a growing concern for many insecticide users. Neonics have been thought to be relatively bee-friendly, but some studies suggest otherwise. The problem lies in their ability to stick around inside the plant and turn up in the pollen and nectar that bees love.
Even if bees aren’t killed, less obvious damage to health and behavior can put hives under stress.
So, what is a gardener to do? Can you use insecticides at all, and are there alternatives?
Here’s how to control pests and reduce insecticide use
You can beat those pests by combining different methods. The fancy name for this is integrated pest management.
First, be vigilant. Limit the damage by catching it early. Check your plants often for signs of discolored or damaged leaves and fruit, and the presence of potential culprits.
Second, know your enemy. This website is excellent for identifying common pests and advises on controlling them.
Once you know what you’re dealing with, it helps to understand the lifecycle of the insect you’re looking to eradicate. When do they first appear? For example, winter moths are a major problem in some parts of the U.S., and their eggs hatch early in the spring. If you catch them in the egg stage, or early in the caterpillar stage, it’s much easier to stop them in a targeted way.
Third, before reaching for the insecticide spray, research all the options for controlling the pest. Some of these are simple; for example, snipping off and composting an aphid covered stem if the problem hasn’t spread too far (see suggestion 1). Failing that, aphids and some other insect pests can be blasted right off some plants with your garden hose!
Finally, if you use insecticides, there are types that minimize damage to non-pests and targeted strategies for using them effectively.
Yes, there are bee-friendly insecticides
First think about when and how you apply an insecticide. Bees visit specific areas, and at specific times. They collect pollen and nectar from flowers, and only do this during daylight. If you’re using a chemical control method, apply it around sunset when the bees have quit working, avoid flowers that are popular with bees, and avoid overspray, where you accidentally spray onto nearby plants that aren’t your main target.
There are chemical options that are relatively bee-safe if you avoid flowers. For example, horticultural soaps and oils, including products specifically marketed as bee-friendly are applied directly to affected plants. These disrupt the ability of insects and insect eggs on the leaves to either retain moisture or get enough oxygen.
You can also use an insecticide that’s specifically targeted to the pest. B.t. is a great example as it only targets caterpillars and is perfect for cabbage loopers, Gypsy moths, and winter moths. Just avoid plants like milkweed that are food for non-pests like Monarch butterflies.
Many common insecticide ingredients have been screened for toxicity to bees, and you can check a list here that rates their risk to honey bees.
Remember, low risk doesn’t mean harmless, so still avoid areas and times of bee activity.
Mother Nature supplies her own insect killers
Remember: Not all insects are destructive. For example, ladybugs love eating aphids, parasitic wasps attack caterpillars, and bees pollinate flowers, ensuring that your vegetables and fruit trees grow the produce you’re hoping for.
Many birds rely on insects for food. Even hummingbirds can’t get by on an all-sugar diet, despite their love of the feeders we put out for them. They also need the protein they get from eating lots of insects, including pests like mosquitoes and aphids.
The beneficial connections between plants and animals are vulnerable to insecticide use. Insecticide harm to bees gets particular attention.
This doesn’t mean you have to avoid all insecticides in your garden, but you should consider ways to limit unintended damage.
You can still use some toxic insecticides safely—if you’re smart about it
Unfortunately, many of the most popular insecticides are highly toxic to bees.
You can still potentially use them if the product doesn’t persist in a toxic state that bees can access, and you are careful about when and where you apply them.
Spinosad-based insecticides like Monterey Garden Insect Spray fall into this category. Spinosad is toxic to bees, but of low risk once it has dried. So, timing is everything: apply it after sunset so it can dry before bees become active again in the morning.
Ortho Home Defense is popular for keeping pests out of your home. Again, the active ingredients aren’t bee friendly, so if you’re using it, keep the application as precise as possible and follow the rules for avoiding popular bee locations and activity times.
For a pollinator-friendly garden, avoid these insecticides altogether
Although it’s possible to minimize the risk to bees, even with toxic insecticides, there are some kinds that are best avoided.
Insecticide dusts are riskier than liquids. If they’re not washed away by rain, dusts can stick around for longer in an active form, even if you’re careful to apply them when bees aren’t around.
They can also get stuck to bees and carried back to the hive, damaging the whole hive.
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