Dealing with Insect Pests in the Landscape
Summer is here, and we see a massive uptick in the numbers of insects on our landscape and garden plants. Fortunately, we have a framework of management strategies to help us deal with them in a responsible way. The framework is called Integrated Pest Management, or IPM for short. IPM focuses on long-term prevention of pest damage through a combination of techniques. Pesticides are used only when necessary and then in a manner that minimizes risks to non-target organisms and the environment. There are five IPM concepts that work together cohesively. These are
- Monitoring,
- Key Plants,
- Key Pests,
- Action Thresholds, and
- Interventions.
Monitoring
Monitoring your plants and correctly identifying the issue is the first step. It’s important to know that not all insects you see on your plants are bad. Some are beneficial and help keep the numbers of unwanted insects down through predation. Some are acting as pollinators. The overwhelming majority of insects you see in your yard are neutral. They are just out there living their lifecycles. Sometimes you will see damage that tells you an insect pest has been at work. Chewed up leaves is a clear sign. Small bumps on the plant that can be scraped off are usually a scale insect, but harder to notice if you aren’t sure what you are looking for. Often, you see evidence of the feeding through sticky sap, which are droppings from insects with sucking mouthparts such as aphids.
Key Plants : Key Pests
The next two IPM concepts, Key Plants and Key Pests, will help you narrow down the offending insect. Dr. Mike Raupp, a former entomologist at the University of Maryland, conducted groundbreaking research in this area. He monitored 30,000 landscape plants on the campus of the University of Maryland as well as 150 private residences. He found that only 10 common plant species comprised 60% of the pest problems. Additionally, the study showed that 12 key pests accounted for more than 95% of the insect problems. This means you don’t have to get a master’s degree in entomology to get a handle on this. You can focus on the plants that are prone to damage and the handful of insects that are almost always at fault. Some key plants and key pests just go together like peas and carrots.
- Gardenias and whiteflies.
- Milkweed and aphids.
- Crinum and lubber grasshoppers.
- Eggplants and flea beetles.
- Sago palm and scale.
I could go on and on, but the point is that if you know up front that a plant is prone to insect damage, you can simply choose a different plant that is less likely to cause you grief. If you must have a gardenia, then you must simply expect the whiteflies and monitor accordingly.
Action Thresholds
The Action Threshold is the next piece of the framework for IPM. Now that you monitored your key plants and have discovered a pest, you then decide if the damage warrants intervention. Most people base this decision on how bad the plants look or how much produce is rendered inedible.
Intervention
Intervention is the last step and can be confusing for most people. You’re able to see the problem, identify the insect, decide to act, but then must choose a method. The gentlest interventions for the environment include physically removing the insects and relying on biological controls. You simply take out your pruners and cut the worst frond off the infested palm or pick the lubber off the agapanthus and drop it into a bucket of soapy water. Maybe you see an aphid colony on your plant, but also notice a ladybug or two. If you give them time, the ladybugs become your free, non-toxic biological control as they eat the aphids for you.
But what if you see no ladybugs in sight and the problem needs to be dealt with? Then it’s time to responsibly apply a chemical. The main thing to know about any insecticide, whether it is organic or not, is that you will almost always kill an insect that you are not intending to target.
The spray or powder will kill beneficial insects as well as pests.
Even so, you should first try the least toxic pesticide that will get the job done. Insecticidal soaps are gentle on the environment and effective for many insects such as aphids, whiteflies, mealybugs, and spidermites. If you are dealing with a more-difficult-to-kill insect such as a squash bug or something else with a hard exoskeleton, you will have to be more aggressive. There are several chemicals that you can use, but organic ones are not usually as effective. If possible, spot treat the areas in question instead of spraying all over. To keep the insects from becoming resistant to the chemical, use a different active ingredient if you must make multiple applications. As always, with any pesticide, remember to read and follow all the directions on the label.
If you need assistance with identifying a pest or figuring out what chemical is the least toxic but still effective, you can always call the Duval County Extension office. We have Master Gardeners here most days to help you with this and other gardening questions you might have.
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