We recently received a call from one of our newly completed landscape projects. They were calling to express concerns that aphids were eating their newly installed landscape plants. As such, they wanted us to spray to stop the infestation.
This reminded me of an interesting book that I read on permaculture, Gaia’s Garden by Toby Hemenway. In the book he explains, “Insects that feed on plants reproduce at staggering rates, quickly surging to astronomical numbers. But the insects that prey on these pests reproduce more slowly and are far fewer in number.” He goes on to say, “that predators always occur in much smaller numbers than their prey and the predator we are looking for is ladybugs [in the case of aphids]”. The problem with ladybugs is that just about the time the ladybugs reach the numbers necessary to control the aphids, the gardener notices the outbreak and sprays insecticide. This kills most of the aphids and the ladybugs. The fast breeding aphids recover within a few weeks, but the ladybugs that have no food until the aphids are in good supply, remain at critically low numbers. Just when the ladybugs feeding on the small population of aphids begin to breed again, a gardener sees that some aphids are still out there. Fearing another plague he sprays again, really hammering the struggling ladybugs. As Hemenway sumises, “A few rounds of the cycle and the ladybugs are all dead, while some aphids are bound to survive.”
This is why we need to practice patience when spraying insecticides. Sometimes we have to let nature take its course and that means having to tolerate aphids on our roses in order to give the predators a chance to kill the infestation. Sometimes spraying is not the answer, patience is.