“Leave it be”
That’s my general policy regarding insects in the garden. I strive for balance. I believe strongly that a relatively diverse habitat, void of harmful insecticides/fungicides/anti-biotics, provides enough support for a variety organisms and no one population can entirely over-throw the others. And generally, that’s true. I can see it each year as the aphids appear in alarming numbers on my roses and tomatoes. Soon after the lady beetles arrive and the aphid populations plummet.
But two of my major nemeses are Japanese beetles and squash vine borers, and I kill every one of those I can get my hands on. The former are relatively new to Minnesota, but I’ve found them destroying many of my plants. They’ll eat almost anything – annuals, perennials, woodies, food crops, ornamentals, etc. I’ve seen them on everything from the asparagus to the zinnias, but it’s the roses they love the most. Especially my new Graham Thomas rose.
They completely cover any new flower buds and destroy entirely destroy them.
As much as I loathe the Japanese beetles, the squash vine borers break my heart every year. I should just stop growing squash, but I do it compulsively and every year I regret it. In early June I meticulously pick off the little, brown, tear-drop shaped eggs every night. But I never find them all and eventually the plants get too large to check throughly. And several weeks later, I get this:
Then the plants should be pulled and burned. But this one is still sitting in my garden, wilting during the heat of the day only to perk up at night. The borers are growing inside the stem, compromising the movement of water and nutrients and soon the plant will die. The borer larvae will drop into the soil to pupate and wait for next year. They crush my squash crop every year, just as the plants set a crop of promising fruit. Alas. I need to treat the squash or quit growing it. We’ll see what happens next year.