Caterpillars, Leaf Damage, and Managing A No-Spray Garden
It’s a late summer day in your garden. It’s still sticky and hot, but you can feel coolness in the mornings and evenings. Fall is on the way. Black-eyed susans are blooming; asters and goldenrods are emerging–the bright pinks of summer are fading into deep golden yellows and saturated purples.
All is well until you notice little green caterpillars chewing on your plants. You immediately think something’s wrong and reach for bug spray to desperately get rid of these havoc-wreaking, freeloading insects. But don’t panic!
It’s easy to get upset about leaf damage, to see your beloved plants with holes and missing foliage. But, it’s A GREAT SIGN. It means the plants are doing their job. And while chewed up leaves might not be your favorite look, leaf-feeding caterpillars are rarely a threat to your plants. Though it may look dire, they will bounce back.
What you see as destruction is simply evidence of your garden working well. Caterpillars are part of the ecosystem, and if we want pollinators, moths, butterflies, and birds, we need caterpillars to eat well.
Moths and butterflies mean more pollination, more healthy plants, more habitat, and ultimately more biodiversity. This also creates a thriving habitat for beneficial insects which prey on pests and keep everything in balance.
Caterpillars are a crucial food source for birds, wasps, spiders, frogs, toads, salamanders, and countless others. A single bird nest with several chicks will need hundreds of caterpillars to survive. Insects, and especially caterpillars, are the foundation to our woodweb that supports everything from skunks to opossums to turtles and foxes.
So, no need to spray caterpillars, as insecticides can damage your plants or inadvertently kill beneficial insects. Once you upset the balance with insecticides, the more rapidly reproducing insects will rebound faster and are likely to do even more damage.
While it may seem like one simple spray does no harm, that’s not the case. Our native bees in Virginia have declined 89% in the past decade. Monarch butterflies are in danger of becoming extinct, as are 430 species of North American birds. Learning to love that insects are using your plants is the most important way to support wildlife and adopt a no-spray zone.
Here are a few things to focus on instead:
Create healthy plants that will provide food for insects and also go on to live the next season. Healthy plants are plants planted in the right place. Choose plants wisely based on sunlight and soil (moisture and pH), and look for plants native your region.
Most soils don't need fertilization, but if your soil is depleted from construction, layering compost and mulch builds healthy soils and healthy plants.
Attract birds. Provide trees, shrubs, and layers of perennials to create cover, nesting spots, and food for birds and bats, which feed on insects.
Don’t introduce “beneficial” insects. Many beneficial insects for sale are nonnative species, and most will quickly fly away, providing short-term, if any, relief from insects.
Have multiple blooming plants each season to provide multiple sources of nectar, but also for your enjoyment. If one plant suffers, focus on what is doing well.
Provide water. A simple bird bath provides drinking water for insects and birds.