There are several different types of caterpillars that appear green in color. These include the smalleyed sphinx (Paonias myops), the greenstriped mapleworm (Dryocampa rubicunda) and the cabbage Looper (Trichoplusia ni). Fortunately, no matter which species of caterpillar is found in a garden, the methods of removing those caterpillars is the same. Killing the green pests is the only way to ensure the safety of your garden and the health of your plants.
Fill a bucket half way with warm water and a tablespoon of dish soap. Pick the green caterpillars with your hand and drop them into the bucket. The University of Minnesota Extension recommends this method to kill green caterpillars when a small infestation is present. The best time to do this is first thing in the morning, as the caterpillars are the least active at this time of day.
Introduce parasitic wasps (Cotesia glomerata) to your garden. Parasitic wasps are natural predators of the caterpillar and either kill the caterpillars when they paralyze them to deposit eggs inside the caterpillar, or when the eggs hatch and eat the caterpillars from the inside out. Starter parasitic wasp kits can be purchased from garden supply stores or from an online garden center, and can be released at any time of the day.
Spray your garden with Bacillius thuringiensis (Bt) using either a backpack or garden sprayer, being sure to follow all of the directions on the instruction label for effectiveness. Bt will kill the caterpillars after it is ingested, but won't harm children or pets that may wander into the garden. It is important that you also spray underneath any plant foliage, as that is where caterpillars often hide.
Apply a chemical insecticide to your garden either first thing in the morning, or later in the afternoon when caterpillars are slow moving. Look for an insecticide with either carbaryl, bifenthrin or permethrin listed as its main ingredient. Insecticides should be used only if all other methods to control the caterpillars fails. This is because insecticides will also kill any beneficial insects that may be in your garden.
Things You Will Need
- Dish soap
- Parasitic wasps
- Bacillius thuringiensis
- Backpack sprayer
- Other natural predators of the caterpillar include lacewigs, spiders, lady beetles, and the praying mantis.
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