The forest floor in spring is covered by a deep carpet of old leaves, new uncurling fern fronds, spring beauties, violets, hepaticas, trillium, Jack-in-the-pulpits and other woodland gems. Above this deep velvet rise the tree trunks, and far overhead are the leafy boughs of the newly greening oaks, hickories, maples, cherries and other trees, providing draperies soft and airy.
So hushed is a forest, with its insulating carpetry, its festoons of foliage covering the soft, limitless ceiling, its sound-stopping tree trunks, that visitors tend to hush their voices also. Only the sounds of the forest’s regular residents, the squirrels, tree frogs, insects and birds break the silence. One hears twigs dropped, the patter of rain, the soughing of the wind in the tree-tops, two branches creaking against one another, the call of a wood-thrush or bluejay or indigo bunting, perhaps, or some other denizen of the woodland.
But did you ever enter a completely silent forest? I once visited a chestnut "cemetery" in Tennessee. Immense chestnut trees, once a glory of the forest but now gnarled gray ghosts, killed by chestnut blight, stood everywhere. And now we worry over the elms and Dutch elm disease.
Is Spraying The Answer?
But is spraying the right answer? Dr. Henry Townes of Warren Rd. told me before he left for Europe in January, a square mile of forest near Scanton, Pa., was sprayed heavily with DDT, experimentally. There was left a silent forest, more silent than the chestnut forest.
Later in the summer, from the opposite hillside, that sprayed square mile stood out accusingly, the forest trees yellowed, sickly and partly defoliated by the aphids that had regained their numbers unbothered by their usual enemies, the lady-bugs, which had suffered much more. The spray put the lady-bug population out of the running for about four years, the aphid population only a few weeks.
Anyone who has watched a bird die in Ann Arbor or elsewhere in the county from the spraying of elms for Dutch elm-disease must feel puzzled about the whole business. A national magazine recently told of a three-way balance among starfish, crabs and oysters along the East Coast, in which normally the crabs eat the starfish that eat the oysters. DDT meant for the harmful gypsy moth killed the crabs, so the starfish ate up the oysters.
Other Controls Possible
Biological control of insect pests can sometimes be brought about by bringing in from elsewhere a predator-insect, such as an ichneumon fly of some type, to prey upon the pest.
In Ann Arbor, parked cars on elm-shaded streets last year were receiving an unusual amount of honey-dew drippings from aphid-infested elms, their lady-bug enemies having been destroyed by spray put on to control Dutch elm-disease.
The City Park Department, headed by Eli A. Gallup, deserves praise for its efforts to curb the illnesses killing our elms. Mr. Gallup doubtless feels very unhappy when residents bring him dying robins, fluttering and helpless from eating the buds of elm trees, even long after the spray operation.
Parent birds make many trips each day bringing insects and grubs and other tidbits to the nestlings. I once watched a hermit thrush clean up during two or three days all the leaf-eating insects on a half-destroyed flowering shrub, after which the shrub began to recover.
Perhaps forestry experts will find a better cure for the elm troubles, which, Prof. Don Baxter once remarked, are many, and not limited to the Dutch elm-disease.