The Nature of August in the Blue Ridge

As the end of August approaches, some animals, especially birds, migrate or become silent so that they are inconspicuous. Insects engage in feverish activity to gather food and reproduce. Naturalists begin to dream about watching nighthawks, hawks and songbirds migrating south and wonder when the first frost will nip their plants. But for the moment it is still a cornucopia of activity in the fields, woods and gardens.

There are many similarly appearing butterflies which are closely related to one another and which we find difficult to separate. One such pair are the American and painted lady butterflies. Both species are now appearing in our yard so it is time to remind ourselves of the somewhat subtle but distinctive field marks which distinguish them. The American lady has two large eye spots on the outer hindwings whereas the painted lady has a number of much smaller ones. Another very confusing group are the “black and blue” swallowtails which mimic the pipevine swallowtail. I do not see spicebush swallowtails often but this male has a very distinctive blue band across the hindwings. Skippers are the most confusing butterflies of all but you may learn quickly to distinguish this tiny least skipper by its small size, yellowish color and lack of wing patterns. The wood nymph is one of the most distinctive butterflies with its brownish color with two eye spots which are flashed periodically.

A very distinctive caterpillar which few notice is the milkweed tussock moth. It warns away predators with bright colors and irritating hairs. It is commonly seen eating milkweed leaves in late summer after most of the monarchs (which prefer younger more tender leaves) have matured. The toxic dogbane plant which is related to milkweeds often harbors a spectacular dogbane beetle which is brightly iridescent, presumably to advertise its toxicity.

People often wonder why birds are given their names. The green heron is a case in point since there hardly seems to be any green except for the tiny lores in this young bird which has a “coat of many colors.” The adults do have a somewhat greenish back. On the other hand this indigo bunting in breeding plumage is clearly a striking blue color and matches its name. It is interesting that its feathers have no colored pigment and are actually black; the striking blue color is caused instead by diffraction of light so that the color changes with the angle.

The cooler weather is late summer, especially at night, causes reptiles to seek out the sunlight to bask. This large female garter snake was enjoying the warmth of the midday sun, perhaps to better digest a meal. This common and essentially harmless species is actually mildly venomous ( https://en.wikipedia.org/wiki/Garter_snake ) although hardly so to humans. But the mildly toxic secretions of its Duvernoy’s gland mimic the evolution of true venom in the pit vipers.

So go forth and enjoy the natural delights of the end of summer. Too soon the weather will cool down but the benefits of the fall season for nature study are many. If “change is good” as it was for the Grandhog Day man, then we will look forward to this natural seasonal change.