A mild winter means a really good season for insects, both pests and beneficials: a cold winter is much more likely to kill them off. So expect more bad guys than usual and be ready with your strategies; expect more butterflies and fireflies and other friends as well.
For example: Every year aphids attack one of my native plum trees, the one that doesn’t get enough sun. This year they’ve attacked the ones that are properly sited as well. How do I know? I saw the ladybugs. Both trees are covered with ladybugs in all stages of their life cycles. They’ll take care of the problem quickly. So my strategy is to do nothing except maybe ask my husband to take some more pictures.
Many garden pests, aphids among them, are host specific: they attack only plants in a specific genus or family. So the aphids on your roses won’t eat your perennials, and the ones on your viburnum won’t eat your peonies or roses. And good bugs like ladybugs are always on the lookout for a good meal. Usually I note the presence of ladybugs and then look around for the aphids. That’s phenology in action. One thing happens, and then something else inevitably follows. Natural processes are made up of many, many complex interactions. Disrupt the sequence, and there usually will be trouble. If I sprayed those plum trees with insecticidal soap, or even just hosed them down with water, I’d get rid of the ladybugs as well.
Same thing holds for most garden pests. Every year in late spring many of my perennials are attacked by four-lined plant bugs, really pretty little guys that do quite a lot of damage sucking on the newly emerging leaves of many perennials. However, they key words here are newly emerging leaves. The bugs are active only early in the growing season, so their damage is purely cosmetic and short-lived: within a few weeks the bugs will have completed their life cycle and the plants will have grown up right past the damage. You won’t be able to tell that they were there. So if I were working in a botanical garden or wanted to open my garden to the public in the near future I would probably spray the bugs with water to dislodge them in order to minimize the damage, but that’s not necessary in a home garden. Nature will take care of the problem for me, as she often does.
So expect more pests and diseases than usual this year, wait and watch carefully, do a little research, and in most cases, do nothing at all. And hope for a cold winter next year.