Tuesday, July 24, 2018

The Cicadas are Singing!

Dog-day Cicada, Neotibicen canicularis
Did you know that Colorado has 26 species cicadas, all of the order Hemiptera?  It seems like the cicadas are earlier than usual this summer, I heard the first one in my garden at dusk in mid-July.  That's a bit disconcerting because according to folklore, the first cold spell arrives about 6 weeks after the first cicada serenade. But that's just folklore, right? Following are some interesting facts about cicadas.

The male cicada produces music with drum-like organs on the sides of his abdomen called tymbals. He contracts and releases muscles to make the tymbals vibrate. Then a large air sac in the abdomen acts like an echo chamber to greatly amplify the sound. Adult cicadas will live for four to six weeks, searching for the perfect mate.  Once the females have mated, they lay their eggs in bark crevices. When the eggs hatch, the nymphs fall to the ground and burrow into the soil to begin their two to five year maturation process. 

Unlike the swarming grasshoppers from the family Acrididae that are properly known as locust, cicadas are generally not destructive to plants. The immature cicadas, called nymphs, develop in the soil, feeding on sap from roots of woody plants.  However, their feeding habits are minimal and do not result in damage to the plant.  When they leave the soil, the nymphs climb to a higher spot to molt. Their exoskeletons split down the back and a mature cicada emerges, leaving a dry cast of the nymph behind.  The fresh adult cicadas will rest on a branch until their wings dry, when they will fly away to find mates.

Although cicadas are some of the largest insects encountered during the summer, they are not aggressive toward humans and do not bite or sting. Cicadas are a food source for several other insects and birds.  The most visible is the cicada killer wasp (Sphecious speciosus), that looks like a giant yellow jacket. Fortunately, this giant solitary wasp is not interested in stinging humans or animals. The adult wasp uses its stinger to paralyze cicadas to transport them back to the wasp’s underground nest to feed her young.

For more information, check out CSU Extension's Fact Sheet: Cicadas.