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.
Cicada nymphs create what we call turrets or chimneys above the tunnel hole where they will eventually emerge. These chimneys are made from soil. They are a positive indication of where cicada nymphs are underground and that they will emerge soon. Cicadas seem to build chimneys in wetter, muddier areas; in dry areas they will simply make holes at the surface. The chimneys will help keep water and mud from back-filling their holes, so they can continue to breathe, take a peek out and prepare to emerge.
Magicicada Tunnel (by Les Daniels):
A cicada tunnel in Bangkok Thailand (by Santisuk Vibul):
Three Magicicada chimneys (by Roy Troutman):
Magicicada nymph turret by Roy:
This is video taken of a magicicada nymph turret. These turrets are often found in wet areas.
Magicicada nymph turret from Roy Troutman on Vimeo.
Santisuk Vibul sent us 3 photos of cicada tunnels/chimneys from Bangkok Thailand.
From Santisuk Vibul: “I found this cicada chimney on the lawn in front of my house on October 22, 2009. In Thailand, this month is late rainy season, there is no heavy rain and there will be no flood in the cicada tunnels, but the cicadas nymphs still build their chimneys. Some authorities said they built chimneys to stay to breathe and prepare themselves for their final molting.”