Dog Day Cicada (Click Picture to Hear the Cicada)

Some call this insect a Dog Day Fly, or even a Locust…it isn’t a fly or a locust, it is a Dog day Cicada…called that because the "Dog Days" are in late summer when the star Sirius is prominent in the night sky.  Sirius is the brightest star in the sky and is part of the Big Dog (Canis Major) constellation, which may be seen in the southeast quadrant of the sky in the northern hemisphere on those hot summer ‘dog days’. That’s when you can hear these creatures singing away from Dawn to Dusk. How loud are cicadas?  Some have been measured at 100 decibels at 20 yards away, which is loud enough to be heard over a lawnmower! Thank Heavens, they stop at night time.

The Dog Day Cicada is also known as the Annual Cicada because the species may be seen every year.  The length of time it spends underground varies from 2 to 5 years, so some emerge every summer.  They are about 1 3/4 inches long. 

Cicadas are members of the Insect order Homoptera.  Other insects in the same order are Aphids, Scale Insects, and, Leafhoppers, to name a few.  
Homopterans have a short, piercing/sucking mouthpart which resembles a hypodermic needle and their wings are clear for their entire length.  Cicadas use their mouth to suck sap.  The forewings of the similar Hemiptera, or True Bugs, have a thickened base.  (Some authorities place these two groups as suborders within the order Heteroptera.) 
Both the Homoptera and the Hemiptera have incomplete metamorphosis, where the egg hatches into a nymph that grows through several stages called instars until it finally transforms into the adult stage.  Adults are reproductive and may be recognized by the presence of wings.  There are over 160 species of cicada in North America north of Mexico.  They come in many different sizes. 

Cicada nymphs burrow underground and feed on sap from plant roots.  The length of time they spend in this subterranean existence varies from 2 to 17 years, depending on the species.  The nymphs have large, muscular front legs for all this digging, as you can see in the picture.

When they are ready to become adults, the nymphs tunnel to the surface and crawl up on the side of the nearest object.  Then the skin splits down the middle of their back and they emerge to inflate and dry their wings.  This is done at night.

How do they make all that racket?  On the underside of the abdomen at the front are two stiff membranes called tymbals.   If you turn a male on its back you will see two shield-like structures just under the hind legs.  The tymbals are underneath these structures.  They have a special muscle attached to them and by rapidly contracting and relaxing the muscle - up to 400 times per second! - the tymbal is "popped" back and forth, much like pushing down and then releasing the top of an empty pop can.  The cicada's special muscle gets tired after a while and the insect then stops to rest.  This is what happens when you hear the buzz of a cicada sputter to a halt.  Each species of cicada has a distinct song

The cicada chorus serves to attract females, and also as warning signals.  This is a risky business for the male because it advertises his presence to predators also!  And there are LOTS of predators of cicadas.  Many species of birds, including large raptors eat cicadas every chance they get.

Some people eat cicadas also. One interesting creature here in Rhode Island who eats cicadas is the Cicada Killer Wasp. They capture the cicadas, inject them with a venom which doesn’t quite kill them, just sort of puts them into a permanent coma, then plants one or two in a burrow with their eggs, when the eggs hatch, the cicada is there (still alive and asleep) for the young wasp larvae to feast upon. We will be posting some web pages on these marvelous creatures soon. We have some pictures from the Narragansett Indian Reservation. 

Cicadas do not have any special defense other than camouflage or flying away from danger.  By emerging in great numbers over a short period of time, they succeed by overwhelming the predators with choices.  Enough will always survive to ensure the production of the next generation.

After mating, the female woodland cicadas use their specially modified ovipositors to cut short slits in the twigs of the trees they are in.  They lay their eggs in the slits and the young nymphs drop to the ground when they hatch.

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