As the end of summer approaches, some things change and some do not. Every morning when I look out the back window I now often see fog in the New River valley due to the cool moisture laden air. This burns off quickly when the sun comes out but you can see that there are some changes coming. Another change is the appearance of some species that were not present before, or at least not for several months. For example this medium-sized red dragonfly, the autumn meadowhawk is well named since its appearance predicts the coming fall season.
On the other hand the silver spotted skipper has been numerous for some time and continues to be commonly seen. But they are now seen on different flowers that have recently bloomed such as the boneset and my favorite the spectacular ironweed. These skippers have not gone unnoticed by certain predators such as a bright yellow crab spider “hiding in plain sight” in the flowers of a purple Brazilian vervain; this spider successfully caught and ate two skippers on successive days! The lack of camouflage by the spider did not seem to be an issue in alerting the prey to a problem.
A butterfly which I recently observed for the first time this summer was a bright orange question mark. It was sunning on a rock wall and alternately showed its outside very cryptic pattern and the inside brightly colored pattern. This species is unusual in that it does not feed on nectar but on sap, rotting fruit and dung, and can survive quite cold weather. I have seen it out at Thanksgiving time but many of them migrate north in the springtime.
Another rarely seen butterfly was a male spicebush swallowtail, one of the confusing “black and blue” mimics of the pipevine swallowtail. I show here an inner view of the wings revealing the light blue color, and the outside which demonstrates a double row of large orange spots. In comparison there is only a single row of orange spots in the mimic female black tiger and the toxic model pipevine swallowtails. I doubt that most humans and certainly birds notice the difference in numbers of rows of spots- the overall appearance is quite similar. But it is striking that both the inner and outer aspects of the wings of the pipevine and its mimics are quite similar.
I generally try to ignore the more difficult to identify skippers but this male zabulon is interesting in that it emerges in two separate broods in May and August in North Carolina. So its appearance now is timely and indicative of the season. With sufficient local knowledge of such timing you could construct a fairly accurate annual calendar.
Our final “bug” is not an insect but an arthropod called a Chilopod. It is commonly seen in the Blue Ridge mountains this time of year on the surface moving at an impressive speed for a critter with this many legs to coordinate. It is locally called the “apple” millipede since if you pick it up and shake it, you will detect a fruity smell. This smell is actually a cyanide compound which the millipede uses to protect itself so it is best not to inhale too deeply! In the wild they are an important part of the detritus community in the leaf litter and can be considered to be interesting and non-toxic under normal conditions.
So the weather is still quite warm except at night (in the 60’s) yet we all know that fall is not far off. As you will see above a careful study of the species of invertebrates will give you a big clue that changes are coming soon. Of course the lack of many of our beloved bird species as they migrate south and the lack of much bird song will have been a big clue also. I am expecting to see the first waves of migrating night hawks pass over our house any day now in the last week of August.