When Magicicada cicadas deposit eggs into a tree branch sometimes the branch dies, the leaves turn brown, and the branch droops like a flag. This is called flagging.
Here are some examples of flagging from the Brood X emergence in Princeton, NJ.
Typically flagging is more impactful to trees imported to North America, but it also impacts native species. The positive aspect is it prunes weaker branches, which helps the tree, and helps other plants in the shade of the tree.
Brood X has emerged in Princeton, New Jersey, but the weather is currently not great for cicadas: less than 50°F and rainy. Undaunted, I visited Princeton yesterday to observe Magicicada cicada behavior on a cold, rainy day.
I arrived at Princeton Battleground State Park around 3:30 PM and immediately head to the short trees and tall weeds, like honeysuckle, that line the perimeter of the park. I was pleased to see hundreds of cicadas clinging to the leaves, stems, and branches of the plants — seemingly without extra effort or discomfort. Many were weighted down by droplets of rain, which seemed to roll off their bodies and bead on their wings like translucent pearls.
Even though temperatures were below 50°F (9°C) I did hear an occasional distress call, and saw plenty of cicadas mating — perhaps they started mating before the rain and cold weather began. No flying. No calls, chorusing, or wing flicks.
Other than thousands of seemingly healthy but (patient) cicadas hanging from vegetation, there were plenty of malformed cicadas on the trunks of larger trees, and piles of exuvia and corpses circling tree trunks. The air around trees stank like ammonia and rotting fat and meat — not unlike a dumpster behind a burger restaurant.
I saw mostly Magicicada septendecim and some Magicicada cassini. No apparent Magicicada septendecula. I saw just one M. Septendecim infected with Massospora cicadina fungus. While there was plenty of avian activity in the area, I did not see any birds or other creatures feast on the docile or dead cicada — maybe I scared them away — maybe their appetites were satiated.
Cicadas dripping with rain:
M. Septendecim infected with Massospora cicadina fungus:
Different types of Magicicada periodical cicada holes found in Princeton, NJ. Brood X, 2021. Generally speaking, their holes are about the size of a dime. You won’t see a spray or kickback of soil around the hole like you would when an animal is digging into the soil rather than coming out of it (cicadas are coming out).
Typical dime-sized cicada holes
A hole with a corresponding mini cicada-chimney
A golf ball sized chimney over a hole
A hole borrowed into a hay bale laying on the ground
A hole in moss
Holes in the underside of a rotten log, with a nymph!
Cicadas will burrow up from the soil of the ground and keep going into the rotting wood of a rotten log! I had to roll the log over to see it.
These are some small cicada chimneys created by Magicicada during Brood II in 2013 in Metuchen. Magicicadas occasionally create chimneys above the holes they emerge from — more often when the soil is wet or ground is shadowed (under a deck, in a lawn mower shed). These were shaded by a large pine.