Swarms of insects have emerged from the ground and are in bushes and trees, but don’t worry, the loudly clicking cicadas are not harmful to plants, trees or humans.
Gus Westerman, Dolores County director for the Colorado State Extension office, said he has received many calls from people concerned about the cicadas, a native species that live underground for three to five years before emerging to fly and breed.
When they emerge, they are not in a feeding mode, he said, and generally don’t cause harm to plants or trees.
“At that adult stage, their only goal is to find a mate,” Westerman said.
When they suddenly appear all at once, it can be alarming to those not familiar with the insect’s lifestyle, Westerman said.
The cacophony of clicking is the male cicada’s mating call, and is made by clapping the wings. In some species, the male will make a loud buzzing “song.” Adults can live four to six weeks.
Females lay eggs in plant stems and twigs. The nymphs hatch, drop to the ground and burrow into the ground.
The nymphs pupate for years underground, feeding on fluids from roots. They develop so slowly that the feeding causes no detectable harm to plants, according to a CSU Extension cicada fact sheet.
A biological clock triggers the generation of nymphs to emerge from the ground and molt into adults. They grow wings and look for a mate to start the cycle again.
Cicada exoskeletons can be seen on the ground from the final molt, especially around the base of ash trees.
They come in waves, Westerman said, starting at lower elevations, then at higher elevations.
Cicadas are part of the ecological system and are a food source for birds and fish. They do not require pest control.
“They are a fascinating insect,” Westerman said. “Every few years, we get to experience the crazy, noisy sound they make for a few weeks, then it wanes and goes away.”
This generation of cicadas is pretty typical, he said, although they appeared to have emerged two weeks early in places because of the warmer spring.
Colorado cicadas are not like the periodical species on the East Coast, which famously live underground for 13 to 17 years.
There are 29 species of cicadas in Colorado, and only four make the clicking noise, reports Mesa Verde National Park, which is also experiencing the insect’s presence and fielding questions from visitors.
The most common of the clickers, or Platypedia, is the species called Putnam’s cicada.
According to a CSU fact sheet about Colorado cicadas, the insect causes little to no injury to plants. Egg-laying punctures produce some plant wounding and may cause damaged twigs to break and die, known as “flagging.”
Cicadas have several natural enemies, including birds, fish and other insects. Perhaps most spectacular are the cicada killer wasps of southeastern and southwestern Colorado that somewhat resemble enormous yellow jacket wasps.
“Cicada killers capture and paralyze adult cicadas of large species, such as the ‘dog-day’ cicadas,” according to the CSU fact sheet. “The wasps dig nest cells a foot or more underground and return with the cicada prey to provide food for their young.”
