The purpose of this feature is to give scout leaders, educators and naturalists an idea of some of the natural events coming up each month. We will try to cover a variety of natural events ranging from sky events to calling periods of amphibians, bird and mammal watching tips, prominent wildflowers and anything else that comes to mind. We will also note prominent constellations appearing over the eastern horizon at mid-evening each month for our area for those who would like to learn the constellations. If you have suggestions for other types of natural information you would like to see added to this calendar, let us know!

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Notes From September 2023

On the afternoon of September 9th we came across these Jack-O-Lantern mushrooms on a habitat survey near Dandridge, Tennessee. I've long wanted to see bioluminescence in mushrooms and even though this species is said to be common in the eastern United States in late summer and fall, we've never been in the right place at the right time to see them glow.

What a perfect name for this mushroom! They exactly mirror the color of a Halloween pumpkin and they do shine at night. The original term Jack-O-Lantern was used to describe a visual phenomenon sometimes seen by travelers crossing bogs or mashes at night. They also feature in Irish folklore. Jack-O-Lanterns were originally carved lanterns made from a root vegetable such as a rutabaga or a turnip.

The glow was very diffused and colorless to our eyes, just two faint patches of light. No details at all could be seen. By using the amateur astronomer's trick of averted vision (looking to one side of the light source) I could see some brighter spots against one of the glows. This trick works because it lets the incoming light fall on the more light-sensitive rod cells of the eye. In fact, the whole scene in front of us could well have been a faint galaxy seen through one of our telescopes. It was a special moment, and we lay there and savored it for a while.

I lacked experience photographing bioluminescence, but decided to give it a try. Having no tripod I wedged the camera and macro lens into a depression in the leaves and started taking test exposures. We held a headlamp on the Jack-O-Lanterns to focus, and this is when things started to become a little more exciting.

The European Hornet is a large non-native hornet first noticed in the United States in the 1940s. We noticed them earlier in the survey seeming to defend certain trees we approached. Though they prey on other insects most of the year, in fall they often incorporate the sugar in fruit or tree sap to their diet.

They are attracted to light sources at night, which explains our difficulties with them when we turned on the headlamp to focus the camera. They're over an inch long and are a little intimidating! Two swarmed around us and one stung me on my forearm before we were able to get back to our lights-off mode to take images.

I saw absolutely nothing on my first 30-second exposure so I kept cranking up the ISO setting on my camera. The mushrooms need to be very fresh to glow and these were perhaps a bit past their prime. I borrowed another trick from astro-imaging and made not one exposure, but ten exposures one after another with the camera in exactly the same position. You place the images in separate layers in Photoshop, make sure they are aligned, and reduce the second layer's opacity by 50%, the third layer's opacity by 33%, etc. You then flatten the image, resulting in a final image which has a much more accurate average of pixel values, which in turn results in both more detail and less visible noise. I finished taking the last few images as rain began to fall from an approaching thunderstorm. The final image is shown below.

Bioluminescence is a fascinating phenomenon that occurs across a broad spectrum of the natural world. The mechanism for the Jack-O-Lantern bioluminescence is the same as we see in firefly displays; a light-sensitive molecule is acted upon by a an enzyme resulting in a chemical reaction that produces light. In these two examples the light-sensitive molecule is luciferin and the enzyme is luciferase. Both names come from lucifer, which is Latin for "light-bearer". The name was also used by the ancients for the planet Venus when it appears in the morning sky. Venus in the morning sky rises shortly before the Sun, hence the name.