One of the challenges of gardening is how to control the pests that like your garden as much if not more than you, the gardener. Some of these pests’ lives depend on your garden for their livelihood- literally eating to remain alive to repeat their own life cycle. So when you have insects on your plants you have to decide “How important is the damage to the overall appearance of the flower in my garden?”
Some insects that eat plants in the garden are good and helpful insects. We all know that bees are beneficial insects. Yes, they might sting us, but basically they are helping to pollinate the flowers or to get nectar to make honey. Without bees we wouldn’t have most plants. So we allow the bees to remain in our garden and don’t use insecticides to kill them.
But there are other equally good or beneficial insects that come to our plants that even do damage to the plants. But because we like these insects, we don’t want to kill them. For example, everyone seems to love butterflies and no one wants to kill them or eliminate butterflies from their gardens. But before they become the butterfly that we love, they were caterpillars that had to eat plants so that they could become (metamorphosis) that beautiful insect fluttering in our garden. Caterpillars need some of the plants that we grow and can become a pest especially if you are a farmer whose livelihood depends on your crops. For example, among the plants butterfly caterpillars need, depending on the type of butterfly, are parsley, or dill or fennel or even carrots or black-eyed-Susans.
Most of us are gardeners who do not rely on our crops for a living, so do we really care if caterpillars eat these plants in our gardens? To rephrase my original question: How much damage is being done by the insects in your garden and are you willing to live with that damage?