If you are like me, you probably never paid much attention to the countless little holes in the foliage all around you, unless the damage was serious enough to make you take notice. I became aware of them only after reading Doug Tallamy’s “Bringing Nature Home.”
I invite you to look around next time that you take a walk in a nature area. The more I look, the more I see the abundant signs of insect-feeding everywhere. In many cases, perhaps most, the leaf damage is infrequent enough that it fails to detract from the luxury and freshness of the foliage. This is particularly true of landscapes dominated by native vegetation and free from non-native invasive pests. Things may take a turn for the worse in the case of crops, ornamental gardens, and ecologically disturbed areas. This can also be the case when an introduced pest, free from biological controls, spreads through the native landscape.
Sometimes, it is possible to deduce who left their signature on the leaves by the shape of the holes, the time of the year, and, perhaps more significantly, by the plant species. Moths and butterflies, sawflies, leaf beetles, katydids and grasshoppers are the main suspects. Often, it is their young, not the adults, which do most of the eating. Caterpillars chew plant material. Adult moths and butterflies prefer nectar, and perhaps pollen; in some cases they eat nothing at all.
Plant eaters exhibit a variety of styles; some chew up the edges of leaves, while others nibble between veins, skeletonizing the leaf. Others dispose of the entire leaf before moving on to the next one. Some are specialists that stick to only one species of plant or a few related species. Others help themselves to a wide variety of plants.
So far, I only mentioned the ones that make holes in leaves. But then, there are leaf-rollers, leaf-miners, gall-makers, sap-suckers … not to mention the ones that feed on all the remaining plant parts, above and below ground; all of them worthy of other posts. For now, I will stick to insects that make holes in leaves. All of them combined eat considerably more foliage than all the larger vertebrates.
I made my peace with all this plant feeding when I realized what an important part of the food chain insects are. Birds, lizards, frogs, small mammals… many of them depend on those herbivorous insects or on the spiders that feed on insects. Even some large mammals value insect food; bears gorge themselves on countless fat caterpillars in preparation for winter. Many carnivores, in turn, depend on the animals that feed on insects.
Nowadays, I look at the traces of leaf eating with joy and curiosity. I visualize that hole converted into a piece of living protein going up the food chain, first a caterpillar, then a song bird and finally a hawk. I wonder about the identity of the ones who stamped their signature in the foliage.
Here are a few which I was fortunate to catch in the act. In these cases I can tell who done it, but there are so many mysteries! Have you solved some of them?
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