Some like it hot.
The recent heat has gotten almost everyone down. Everyone, that is, except the cicadas. Hear them singing from the tree tops, and notice that, as the temperature increases, their song becomes louder and stronger, reaching a heat-enhanced crescendo of lust.
The name cicada comes from a Latin word meaning ‘buzzer.’ It is the male insect that is the buzzer, singing his song of seduction, hoping to entice a similarly lonely female to join him. He creates his ballad in a unique way. Many insects rub together limbs to make their shrill, high-pitchedsong. The cicada, by contrast, has an organ called a timbal, which vibrates like a drum skin to produce its temptingtune.
The timbal can vibrate up to 390 times per second, producing sounds up to 120 decibels. This is as loud as being adjacent to a plane on an airport runway or an ambulance siren up close. If you consider that any prolonged noise above 90 decibels can damage hearing, the singing cicadas could constitute both a noise violation and a potential health threat.
The singing summer cicadas are not the famous periodic variety that shows up every 17 years. During the dog days of summer, it is the dog day cicada, an annual cicada, that stands out.
In the world of cicadas, this species got the short end of the stick. While most folks know of the legendary longevity of cicadas (there are some varieties of this species that live to be17), the dog day or annual cicadas live only two to eight years, and lead a very different life from that of the periodic cicadas.
Besides the difference in life span, the two species of cicadas look very different. Annual cicadas are larger than the periodicvariety. Different coloring of body and eyes will also help to identify thespecies. The dog day or annual cicadas are dark with green markings and have green to black edges on the wings, while periodic cicadas have red eyes and orange legs, with wings veined withorange. Both varieties have five eyes: two very large ones with three smaller ones between the big eyes.
Lots of reports have been coming in of sightings of adult annual cicadas, as well as sightings of their exuvia, the empty brown molt which they shed after their fifth “instar,”or growth spurt. The adult insect is quite large (about two to three inches) and distinctive, so misidentifying it is almost impossible.
In late July and August through October, the annual cicadas are emerging from these exuvia. Unlike the periodic cicadas, which synchronize their populations and emerge as adults in large numbers all at once, the dog day cicadas are unsynchronized, so different individuals can emerge everyyear.
Cicadas fulfill their destiny by laying eggs in the tips of tree branches after they have mated. The eggs hatch into nymphs which fall to the ground and burrow into the soil. They will live in burrows below ground for a few years before emerging and crawling up a tree. Their exoskeleton splits and the adult, called an imago (pronounced ih-MAY-go), emerges and climbs to the top of the tree to sing and begin the cycleanew.
It’s hard to imagine a summer night without the sound of cicadas. As I said, some like it hot; and the increase in heat brings out the cicadian rhythms from these drummers of summer. And, at this point, they’re just warming up.
Suzan Bellincampi is director of the Felix Neck Wildlife Sanctuary in Edgartown.