[Production Note: open with music: 'The falling leaves . . . .'] Aphids are doing very well this summer, in spite of the wet rainy weather in July. Greenbug aphid on turfgrass was the first and most noticeable, while others developed less obviously.
Now, however, the results of a summer's worth of sap feeding by maple aphids is quite apparent as damaged leaves are falling from maple trees and accumulating on the ground below. There are many species of aphids that will attack maple trees, and it should be re-emphasized, these are not the same species of aphids as are found on other trees, turfgrass, honeysuckle, vegetables or flowers.
When trees are heavily infested, large amounts of honeydew usually collect on the leaves and on sidewalks, patios, windows and cars under the trees. Frequent rains may have limited the noticeable build-up of honeydew this summer, though we have not been as fortunate in other years, and the 'sap' dripping from trees has been the major symptom of infestation. This summer, maple aphid populations went essentially unnoticed until the leaves began to fall. Summer leaf drop is a common occurrence with maple aphids and it is not uncommon for trees to nearly defoliate by this time of the year.
As severe as the problem may appear based on the number of light green to yellow leaves that are on the ground under the trees, this insect attack is not fatal to otherwise healthy trees. We would not recommend spraying trees at this late date to control the aphids. It would be better to let nature run it's course and preserve the natural enemies that are present (sometimes in abundance by now), rather than apply an insecticide when it is too late to do any good. The same would be said of tree injections. Wounding trees with the injection process after the aphid population has already caused summer leaf drop is not prudent. Bottom line: save your money.
['Falling Leaves' music up; fade out.]
This article originally appeared in the August 26, 1992 issue, p. 147.