Backyard Wisdom - June/July 2021
by: Gilbert A Smith, ISA Board Certified Master Arborist

I got a call from a client this spring (2021) asking me to check her Beech tree this summer and spray any caterpillars that might kill it. This Beech is her favorite tree. I told her that I would do that and not to worry because caterpillars on Beech trees are normal, natural and healthy. She replied with enthusiasm, “Don’t tell me that! I don’t want my tree to die!”

I’m reading a great book called, Bringing Nature Home by: Dr. Doug Tallamy. I highly recommend it for anyone who loves our natural world. In it he suggests that we plant native trees, shrubs and perennials from our area because they (unlike non-natives) attract wildlife to your home landscape. Native plants help support the animals and birds we all love and whose populations are declining due to urbanization.

Professor Tallamy suggests planting Beech trees because they attract and support many of our favorite birds; including Chickadee, Downey, Pileated and Red Bellied Woodpeckers, Indigo Bunting, Purple Finch, Scarlet Tanager, Tufted Titmouse, Nuthatch, Wild Turkey, Wood Thrush, and Yellow Bellied Sapsucker. Who wouldn't want to save a Beech tree that attracted so many wonderful birds? But, here’s the catch. The beech tree and all of our native trees and shrubs attract birds because they support insects, especially caterpillars which feed and support birds. Is this a catch 22? Will the bugs kill the trees? The unequivocal answer is: no the caterpillars will not kill the trees. In fact up to 40% of a trees’ leaves can be eaten by caterpillars and the tree won't suffer in the least. In all of nature there is a healthy give and take.

When you plant non-native trees like Norway Maple or Buckthorn, whose leaves are not eaten by native caterpillars, those wonderful birds will not be able to feed their young. Non-native plants and bug free landscapes are a great part of why our favorite birds are disappearing. AND, to be absolutely clear, bird feeders do not supply the amount of protein necessary to raise young birds, their parents depend on insects.

Our native trees have been evolving with birds and bugs since before the human species made its debut. They have worked it out so that the caterpillars (which incidentally become beautiful butterflies and moths) are controlled by the birds. The trees depend on the birds. The birds depend on the trees. It is a perfect system. That is, unless we interrupt the system by the introduction of non-native plants, non-native insects, diseases or especially pesticides.

It takes the practiced eye of an educated Certified Arborist to diagnose when something is out of whack. That’s why the Arborsmith crews are always inspecting your trees. But please don’t be upset when we tell you that bugs are normal, natural and healthy in any well kept landscape.

Notes:

1. It’s hard to find many native Beech trees in Northeast Illinois but drive just 50 miles east to Indiana. You will find that they are not just native there and throughout the eastern states but they are the climax forest. That means that if left alone the forest will be dominated by Beech and their friends the Sugar Maples.

2. Here’s a beginner's list of trees that attract and support birds: Oak, White, Burr and Bi-colored especially, Willow, Wild Cherry, Wild Plum, River Birch, Poplar, Aspen, Crabapple, Sugar Maple, (obviously not Norway Maple) Pine, American and Siberian Elm, Shagbark Hickory, Hawthorn, Alder, American Linden, Hazelnut, Walnut and Beech.

3. Oaks: “Oaks are the quintessential wildlife plants: no other plant genus supports more species of Lepidoptera, (butterflies and moths) thus providing more types of bird food than the mighty Oak.” pg.148, Bringing Nature Home, by D Tallamy

Mother Nature’s Moment - My Leaves Have These Weird Bumps and Lumps on Them!

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